Tuesday, December 31, 2013

A few things that made my 2013 interesting..

As of my regular practice since 2011, I am here writing a few (30, to be precise) things that made my 2013 interesting. Year 2013 had its own ups and downs. But just like 2012, this year too was pretty fine and probably the best year yet. The year had its sad moments and hard decisions. I made many important decisions on my own.

Now time to look into some random things that made me 2013 a unique year. This is mostly an unordered list, except some logical ordering. This is a list of events in the order that appear in my mind at this moment - not in the order of importance.

1. The new year's eve of 2013 itself. That was a colourful new year.

2. Finishing touches of 2013. Year 2013 had a rushing set of events till the last moment. The year is ending in style. Never had a year end vacation like in 2013 before.

3. Multiple plots and locations. I spent the year in Portugal, followed by a summer vacation in Sri Lanka, and back to Europe, but to Sweden. Just returned to Portugal last night. Other short-term locations include Spain, Finland, and Denmark. This made 2013 a year full of travels for me.

I got used to the airports, buying tickets online, trying to connect to the airport wifi, booking hotels and hostels.

4. Cruise to Helsinki - This was my first cruise, from Stockholm to Helsinki using Tallink Silja line (M/S Silja Symphony to Helsinki and M/S Silja Serenade to return, though both are identical cruises and they look the same). The wave was strong as there was a storm. Planned acrobatic activities on the cruise were canceled due to the bad weather during the return trip which was on the Christmas day. Shaking cruise made me a bit uncomfortable - but that was a comfortable sleep with the rhythm, once I got onto the bed. :D

5. Snowy night of the EMDC Winter Event at La Vall de Núria - The snowy night full of ice. I lurved it. That night was just perfect (Photos).

6. Exams and Presentations - All the semester (all 3!) exams were on this year. This made 2013 a year of exams. EMDC required us to do a lot of presentations. Some were fun; some were a bit boring. But we enjoyed them all! I have never done this many presentations in previous years. :D

7. A lovely surprise birthday party by the friends at Bairro Alto. It was the best.

8. Friends and Good byes - I never had to say good bye to many people in my life before. As long as we are in our motherland, the good byes are not that strong. We will meet again someday for sure. But in an international environment, we are not quite sure when we will meet some of our friends again. I made quite a good friends in 2012 to whom I had to bid farewell to (and they to me) in 2013.

Each year brings me its own set of friends. Made some good friends - from China, India, and all over the world in this year.

9. Depressingly dark Stockholm. It was winter, the day time shrank and made Stockholm a city of darkness. 

10. Learning some Chinese. I also became addicted to Chinese music and also more into Romanian. Read my top-3 picks of music on Stockholm - Month 4.

11. Nightly walks at Parque das Nações. Also a remarkable night stay in a cold winter outside Centro Comercial Colombo.

12. Fine restaurants in Lisbon and their hospitality - buffets at New Wok Chinese restaurant, friendly waiters of Restaurante Destino of Restauradores, and frequent visits to Restaurante Kathmandu of Arroios.
13. Summer in Stockholm - It was really pleasant with long day time. It was dry and not too hot. Can never forget the beach baths and the forest walks in Farsta.

14. Getting runny nose in Helsinki - That was a mistake assuming the Helsinki weather will be similar to that of Stockholm, based on the temperature predictions. Helsinki was much wet and windy, which made the weather more unpleasant. That was a wet Christmas - not a white Christmas!

15. Street food in the food market of Copenhagen. I have never enjoyed these street food  before.

16. Reindeer meat and Glöggi, Scandinavian style. Not to forget the elk meat. I have started to love the Scandinavian dinner.

17. Movies at Campo Pequeno, Centro Comercial Colombo, and Centro Comercial Vasco da gama of Oriente.

18. Playing Chess in Obidos, while enjoying some quality Ginja.

19. Enjoying the Sun at Setubal. The boat was stylish and the Sun was warm. A highlight of the Lisbon Summer trip.

20. Vila Franca de Xira, in Autumn 2013. A village full of cobweb and free internet by the river! God bless you who installed wifi connectivity by the river side, and left it open to public.

21. The last few days in Portugal before leaving to Sri Lanka for the summer vacation.  We were keeping ourselves busy by travelling north and south of Portugal. Rio Douro at Porto - The Sun was extremely warm. Matosinhos beach still had freezing cold water. The water was warm in Lagos, and also I enjoyed the cliffs of Lagos. Still there was sadness - I had to leave Portugal in a day or two.

22. Barcelona Carnival (Photos).

23. EMDC Summer Event - The walk in the Fejan island in the darkness was unforgettable.

24. Hostel stay in Madrid and Barcelona. I have never stayed in hostels, even during my school days. To be specific, sharing a room with random strangers (in Barcelona) was new to me.

25. Cooking in Lisboa (Photos). I started cooking during the Easter Vacation in Lisboa. It turned out pretty well, and I continued to cook daily in Stockholm, which saved me a considerable amount of money that I used later for my travels in Europe. 

26. Living in a shared room. Luckily my room mate and I had so many common qualities. We sleep late. Noise and light do not disturb our sleep - that means, we were able to work while the other one was sleeping. We shared our food - that encouraged us to do new cooking experiments (Photos of my cooking in Stockholm). Since my room mate was a vegetarian, we decided to cook only vegetarian meals. That made me almost a vegetarian for 4 months - I had vegetarian meals except during the rare occurrence of eating outside with friends. I was still healthy. :D

I have never lived in a shared room before, as I prefer some privacy and a private space. Just like cooking, this too was a new experience and an achievement of 2013.

27. Kindness showed by random strangers in Lisbon and Stockholm. I once asked a route from a stranger in Stockholm - he was unsure himself. He pulled out his smart phone, did a quick search and provided me with a detailed information within a minute. Similarly, another Swedish came all the way to a metro station, while mentioning that he really wish to visit the Adam's Peak in Sri Lanka (also known as Sripada, in Sri Lanka).

28. Interviews. They were interesting.

29. Internet Communications. Living away from home and then from Lisbon, made me use the Internet more to communicate. I wanted to be offline once in a while. However, the distributed nature of my life made my life compulsorily online.

30. Shopping - lots of it. Not only for buying stuff - also to have a window shopping - in Lisbon, Porto, Stockholm, Helsinki, Copenhagen, and Malmo.

Thanks for reading my list till the end. If you are really interested, you may also read the blog post on the year 2012 and the year 2011. :D

I wish everyone of you a very happy new year 2014. :)

Friday, December 20, 2013

Application Scheduling in CloudSim

[19/12/2013] Today was the last day at KTH, marking the completion of the semester 3. We did the final project presentations yesterday and today. My presentation slides on my project "Application Scheduling in CloudSim" are given below. I will miss my friends in the coming semester, as I am the only one EMDC guy returning to Lisbon.

Saturday, December 14, 2013

Stockholm - Month 4

Scenic beauty of the lake..
[15/12/2013] - Finally we are completing our 4th month in Stockholm tomorrow. Few more days to complete the third semester, when all of us will disperse to different countries from Sweden. This month was interesting, but was dark with very little sun shine. Interestingly it didn't snow much yet here. Just snowed twice. Earlier this week once and today with rain. No evidence of snow remains either. All the snow has melted down. 
At the examination
[12/12/2013] - Today at the examination, the invigilator looked at my Swedish Residence permit with the photo taken just 100 days before, and then looked at me. Then again at the ID, then at me, and then asked me, "Is it really you?" (with a big smile of course). I said, "yes, it is me. Now I look older in the winter". She certainly was not satisfied. She asked from her colleague. He too was kinda confused. Then they decided to trust me. Probably they were just playing with me, because they were smiling. Probably my appearance has indeed changed drastically over the 100 days, away from the motherland of Sri Lanka and the loveland of Portugal. haha.. Nevertheless, that was fun. Blame my laziness for not shaving even past the Movember-deal.

Philosophy of Science 
We have received the results for the Philosophy of Science. An "A" for my essay, "Creation-Science vs. Evolution. An induction based analysis". I am happy about that, as I had done a considerable research on that area for the paper. We had so many presentations. I love student presentations. :D

Lots of Music
I have spent lots of time listening to music, or I often do other things having the music as a background. In the city of darkness, music keeps me alive. ♥ I am listing some of the music I enjoyed most in 2013 below. These songs are pretty old and not really released in 2013. But I happened to listen to them for the first time in 2013. So for me, they are music of 2013. :D I hope you will enjoy these songs, as much as I do.

1. Inna (Romania) - Amazing (video in Praia das Maçãs (The Apples beach), Sintra, Portugal).

2. The Myth (China) - Endless Love. [bilingual song - Chinese and Korean].

3. DaiQing Tana (China) - Qinghai Lake (video in Qinghai Province, China). [bilingual song - Chinese and Mongolian].

Monday, December 2, 2013

Death by PowerPoint - Cantopop

Today we did a presentation showing how not to prepare a PowerPoint presentation for our Scientific Writing and Communications class. As an example, a presentation titled "Cantopop" is created, depicting the improper use of PowerPoint. Cantopop is the Cantonese Popular Music. The presentation was intentionally made to be a bad powerpoint presentation. The slides of "Death by PowerPoint - Cantopop" can be found below.

Friday, November 29, 2013

An introduction to CloudSim

Today I did an introductory presentation on CloudSim for the Implementation of Distributed Systems module. The presentation slides can be found below. The presentation and the discussion went up to 50 minutes. Everyone of the class was highly involved in the presentation discussion.
Introduction to CloudSim.pdf

Thursday, November 14, 2013

Game Theory - Concepts and Games..

Today we had two great presentations during our Advanced Distributed Systems class at KTH. Xiao Chen presented concepts of game theory, and games, during the 50 minutes. I did the latter part of the session describing the applications of Game Theory in Real life situations - another presentation which last for 50 minutes, can be found here. Xiao's presentation is given below for your reference. We had an awesome time.

We have almost completed our third month in Stockholm. Luckily it hasn't started to snow yet, though the days are extremely short, where the Sun sets at 3.30 p.m. Good for us. Not sure whether I am waiting for snow or just want it not to appear at all. Good work, my friends. Thank you Xiao for sharing the presentation.. :D

Game Theory - Applications in Real Life

Today Xiao Chen and I presented Game Theory in our Advanced Distributed Systems class. I presented the applications of game theory, and how it is applied to real life situations, mainly evolutionary game theory for evolution, network traffic modelling, and auctions. My presentation and the discussion lasted for 50 minutes. Have a look at Xiao Chen's presentation on the concepts of Game theory and Games, which was followed by my presentation. My presentation slides are given below. They also can be downloaded at Game Theory - Applications in real life.

Game Theory - Applications in real life

Thursday, October 31, 2013

Seasons of Portugal

Tagus River, cloudy in Vila Franca de Xira
When I was in Sri Lanka, it was not really easy to differentiate each of the months. However, in Europe I am able to remember each events easily in a time line. This is, I recognize, mostly because of the different seasons. In Portugal, summer represents life. Winter is usually wet and boring, with many rainy days. My October visit to Lisboa - cloudy and drizzling. Winter is not here yet. The autumn days! Missing summer.

Saturday, October 19, 2013

Stockholm - Month 2

KTH, red in Autumn!
[25/09/2013] - Now the time has started to go fast. Cooking has become a daily routine. Final year gives more pressure than the first year, though the workload is relatively low. This is because, now we have to look forward for our future, what is beyond EMDC? To focus on our next stop. First years do not have this to think about. Weather is getting colder. 4  °C right now, at 10.15 a.m. 

[16/10/2013] - Two months have passed in Stockholm. Autumn makes everything colourful. The KTH main campus, which looked green, looks red now! It gets to subzero temperatures. The central heating is still not turned on, in the apartment. But it doesn't get much cold inside yet, when the windows and doors are closed. Days are quite busy with the Philosophy of Science essay, and it is almost finished by now. Time to focus on the project.

Monday, September 16, 2013

One month in Stockholm - Pleasant and unpleasant surprises..

Kungliga Tekniska Högskolan
[16/09/2013] It is one month, since I reached Stockholm. The day time of Stockholm shrinks pretty fast - 5 to 6 minutes per day. When we came here, the Sun used to set around 9 pm and the sun light was visible till the 9.30 pm, from as early as 5 a.m. Now it seems like 6.30 a.m to 7 p.m. Autumn is here already; it keeps raining. [Sweden Weather]

Cultural Shock, again?
When I was in Sri Lanka, I used to think that all the Europe is same. But living in Sweden shows that it is not the case. Coming from Portugal, I was able to see some differences. Some pleasant and some not-so-pleasant surprises. 

I am listing down some of my unexpected observations in Sweden. Some of these are probably just because of the higher expectations.

1. Friendly People
Just like in Porto and Lisbon, I was able to meet friendly strangers here in Stockholm, who were willing to take some effort to provide with some help, finding the way to the metro station, or helping me understand something written in Swedish.

Recycling is a serious business in Sweden. You can return the plastic or glass bottles, and beer cans and receive 1 - 4 SEK coupons from the super markets. One day, I was on the metro, and a lady who looked like a gypsy came and sat next to me, with a huge garbage bag. Eventually, I realized that the bag indeed contained garbage, from the foul smell. I had to wait a few more stations for someone from the seat in the other side to get up, before switching the seat, not making it obvious, as I didn't want to offend her. She had collected lots of bottles, tins, and cans from the trash bins of the streets or super markets, so that she can probably have dinner that night, by submitting them. After that incident, I also noticed many people doing the same - putting their hands into the trash bin. Probably, they are homeless or asylum seekers from other countries. Still, it looked a bit weird.

After having a coca-cola, we throw the bottle into the bin - and someone collect it to receive some coins. Effectively, everyone is happy. Empty trash bins.

Woods of Vidja
3. Forests
I never thought I would be able to see thick forests inside the Stockholm city limits. As I walked, I noticed a deer in the woods one day.

4. More openness
Even with my limited exposure to Swedish, I was able to see the cultural differences. Compared to Sweden, I can say that Portugal is much more conservative.

5. Dirt
Probably, this won't make much sense. May be, this is because of the high expectations - I found Stockholm having more dirt on the metro stations and was a bit shocked. Also, it seems there are so many beggars around the city, than I would imagine. These all may be due to the utopian depiction of Scandinavian countries we were given in the southern Europe.

6. Crowds
In real life, Stockholm metro stations didn't seem as stunning as portrayed in, "Stunning underground art In Stockholm’s metro station". Mixture of both slowly moving people and people rushing to catch the metro and altogether the presence of an unorganized crowd in the metro stations make it almost impossible to enjoy the metro art. The extremely long walk imposed by the long metro stations is not really fun, when you have to run to catch the metro before you lose it, as the next one would take 10 minutes to come, unless for the cities in the centre, which can be reached by multiple lines including all the red and green lines.

7. Public Transport
Buses are not that frequent when we go farther from the downtown. For example, a bus leaves from Farsta to Vidja only once an hour, and seems to be the only option of public transport that connects these two places. Probably people in Stockholm do not use the public transport much, unlike in our countries. I should not forget the infrequent buses to Taguspark in Portugal, which is worse. It is possible to buy the bus ticket using your mobile phone. But it is impossible to buy the tickets from the driver, on board. That means, you should always have your ticket before you board on the bus.

8. Multi-cultural/Cosmopolitan City
It was not that easy for me to find another Sri Lankan in Lisbon. But I was able to see plenty of them in the God Ganesh temple run by Sri Lankans. I was also able to see a huge number of Chinese and Indians. Not to forget the instructions in Chinese Language in Arlanda Airport. I was also able to meet many international students in the student apartment. KTH surely welcomes foreign students.

KTH Royal Institute of Technology
Our courses began on the 2nd of September, and we have already completed two weeks of our courses.  The first 3 out of the 4 courses have already begun, and the last one begins at the end of September, mostly covered in the period 2. We have the below courses for the semester - IC2002 Philosophy of Science, ID2220 Advanced Topics in Distributed Computing, ID2219 Implementation of Scalable Distributed Systems, and LS2306 Scientific Writing and Communication.

We have received the project and the assignment descriptions to do for the semester, and we are getting busier with our studies. Right now, busy reading the book, "Philosophy of Science: The Central Issues" of Curd & Cover.

Sunday, September 15, 2013

uCertify.com, the online version of the PrepKit - Worth buying?

I haven't reviewed any site or service for a long time, after my blog post "Is Freelancer.com a complete scam, or a partial scam?," which became quite popular because of the back links it got from multiple users of the site. I was recently approached by uCertify to provide a neutral review on their online platform. Since this is related to my blog, I decided to review their platform. I was given access to CompTIA (Computing Technology Industry Association)'s CLO-001 Cloud Essentials PrepKit (Preparation Kit), for this review. This review is neutral and unbiased, and is solely based on my personal opinion and observation. Feel free to drop a line or comment, if you have something to add to this post.

The course material as well as its online platform seem pretty good in the way they are organized. I have no intention to sit for the CompTIA exam. However, since I am experienced in Cloud Computing for more than 3 years, I was able to scan through the course material pretty easily, over the weekend.

I like their promise of 100% money-back guarantee, if you didn't pass your exam in your first attempt. This is surely ahead of what their competitors have to offer, at least among the sites I have compared with. I read some negative remarks on PissedConsumer, on the refund. However, I can not say much regarding the users' subjective opinions, as I have never tried myself to refund to have my own.

Study Planner, showing the progress
uCertify.com online service provides a solution for those who had issues with having uCertify software installed in their computer, probably because of their operating system being incompatible. uCertify.com interface works smoothly with Windows, Linux, and even on the mobile interfaces. Coming back to review the site, from the beginning, the interface of uCertify.com (from here onwards, I will use uCertify to refer to uCertify.com, and 'product' instead of 'site', as I presume both have similar interface and quality), will surely impress you.

You can set your start day and the target day (probably the day of your examination or a few days ahead of that) in the StudyPlanner. Study Planner offers a one-stop view of your progress, and access to all the course material from the single page, also letting you share the pages and progress via social networks, socializing the study progress.

"Pre-Assessment" section provides a quick start and lets you know your position before you begin the course material. If you are an expert in the domain, this can help you move quickly in the preparation, or otherwise helps you have a realistic time line regarding the finishing date of the course (or the day of examination).

All the assessments (Pre-Assessment, Practice Tests, Post-Assessment, exercises, and quizzes) come in three modes, Test, Learn, and Review. "Test" comes in the format of the regular exams, where you provide the answers, finish/end the exam, and receive your score. "Learn" is where you can either skip or attempt the question, and see the answer immediately. "Review" mode comes with both the question and answer, hence not letting you attempt the question at all. "Learn" mode appears to be a hybrid of "Test" and "Review", and I prefer the "Learn" mode much more than the review mode. Number of items and the time of the test can be configured.

"Chapters and Lessons" is the course material, similar to an e-book, which lets you learn or revise. I would probably not recommend learning through this as the sole mean to learn the technology - cloud computing, in this case. This can just be considered a supplementary material, along with your regular text and hands-on practices, at least, if you are focusing more than just a mere certification. You can start the reading from where you stopped last time, or from the last page you read so far, which is pretty useful in bookmarking.

"Exercises, flash cards & quizzes" is the section that I found most impressive. These are organized into the 12 chapters, following the same structure of the "Chapters and Lessons" section. There are 190 flash cards, following the material provided in the chapters and lessons. Quizzes and Exercises follow the same format, where "quizzes" should be attempted first as they test the fundamental aspects, where "exercises" evaluate the understanding of more complex material.

"Practice Tests" contains 200 questions, as 4 sets of 50 questions. I would prefer more questions and coverage in this section. "Post-Assessment" is similar to the section "Pre-Assessment". The difference is, you are supposed to attempt to this, only when you are done with the previous sections, and consider yourself ready for the exam, with at least 90% score in the practice questions.

"Glossary" comes with a list of the terms related to the course. However, I am not impressed at all, with this section. For me, it lacks considerable terminology, and also poorly organized, than a mere bulky page of plain text, almost. No links, internal, external, whatsoever. I presume, this section is a later addition and still needs improvement.

Interestingly, you may also get a certificate of completion, when your readiness is at least 90%. Though this doesn't provide any real value as your "real" CompTIA certificate, this probably is yet another interesting feature of the service.

While reviewing the sites, I didn't fail to check the comments from the online forums regarding uCertify. I always motivate others to check the reviews before trying the services. CertGuard offers such a service for the examination preparation materials. uCertify is marked as a SAFE site. uCertify is the 2nd among the TOP 20 SAFE SEARCHES (CareerSaver being the first). This shows many new students are attempting these sites, and indicates their popularity.

All the best for your examination preparations!

Monday, September 2, 2013

Stockholm - Weeks 1 & 2

[02/09/2013] Probably because it is the late summer, the rainy days are getting frequent here. However, we are still able to enjoy the sun shine and the long days. We had the EMDC Summer event at Fejan from the 20th - 22nd of August, which was a remarkable event, following the EMDC Winter Event we had last semester at Nuria.

Stockholm is full of water - lakes and islands. I didn't expect it to be a Venice of the north. Literally you can travel around the city with a small boat, kayaking. I visited the old town at Gamla Stan, the woods of Vidja, long walk by Långholmen island.

We had a welcome reception at the city hall, with the KTH President. He addressed the new students at the hall where the Nobel Prizes are awarded. Within the few days, we also have made friends with lots of people. 

Everything is pretty much expensive here, and to manage with the same amount of scholarship, we have to be really careful with what we spend. I also feel missing Lisbon and its hot summers. However, I hope the stay at Stockholm will be as interesting as Lisbon.

The road to Stockholm..

Leaving Sri Lanka for my second year of studies at KTH, I realized, how the time flew fast. On the 16th of August 2013, I reached Stockholm. This was after a break of 1.5 months in Sri Lanka for the summer. I had some Euros with me, which I wanted to convert to SEK, when I reached the Arlanda Airport North (ARN).

I am staying at Kista student apartments, which is on top of the Kista Galleria, close to KTH Kista campus, where we will have most of our lectures. Unlike Lisbon, reaching our apartments or the city centre from the Arlanda Airport is not that economical. Taxi is pretty much expensive. First I bought the SL travel card for 20 SEK, which also costs 790 SEK per month for the monthly allowance, without the student card (they didn't accept the Portuguese Student card, and they require a Swedish card, where we are yet to receive our KTH Student card).

Airport Express and Coaches
I have tried multiple travel options to reach the airport, and reach the apartment from the airport, during my stay in Stockholm for the past few days. First I used the airport coach Flygbussarana, which accepted my Portuguese Student card and gave me the student discount. So this was an economic option, as I was able to reach the central metro/train station in 50 minutes for 79 SEK (When I checked again in the October, I was told that the student discount is no more offered to the airport shuttles even with the Swedish student card. So I had to pay 99 SEK.). These tickets can easily be bought from both the airport and the T-Centralen central metro station from the airport shuttle ticket machine.
From the T-Centralen, the central metro station, I took the metro blue line leading towards Akalla, and got off at Kista. Similarly I tried the airport express train to go to the airport on the 23rd of August, from the central station. They didn't accept my Portuguese student card as an international student card. So I had to pay 260 SEK, which is pretty expensive. With the KTH student card (or any other international student card that is in the acceptable format - that is, a smart student card. :D), you will receive a 50% discount on the fare. This is the fastest option, as it lets you reach the Arlanda North (ARN) station in 20 minutes. ARN consists of the terminal 5 International Terminal, and Arlanda South (ARS) consists of the other terminals.

There is also another airport coach from Flygbussarana that goes directly from Arlanda Airport to Kista/Sundbyberg/Bromma Airport. You can get down at Jan Stenbecks torg bus stop and walk towards the Kista apartments. I have never tried this option myself - somehow missed it. (Thanks Shelan for the update. :) )

Public Transport
It is also possible to use the public transport to Kista from the airport, which I tried on my way back to the apartment on the 27th of August. With the SL card, this will be free, as we are using  the public transports. Just go to the bus terminal 15 at the airport, and go to Märsta station by the bus number 583 that operates between Märsta station and Halmsjön. At Märsta station you can take the commuter train to Helenelund, and from there Kista is in a walking distance, and can also be reached by the bus 523 or 603.

Student status letter, indicating I have been admitted to a Swedish University and Insurance Document were sent by the university, as early as the mid of March. We also received the student agreement, stating that we will receive the scholarship to cover our expenses in Sweden. Information regarding the Swedish residence permit is found at the EMDC website.

Residence Permit
We applied for Swedish residence permit online from Lisbon in March itself. Since we already have the visa to enter Schengen region, we didn't have to provide our biometric data (finger prints and the photograph) from Lisbon or from our home country (Since Sri Lanka doesn't have a Swedish Embassy, I would have to go to New Delhi for this, otherwise). Rather, we provided them once we reached Stockholm. The residence permit to be sent to our address in Stockholm.

Migration Board
Reaching the migration board is pretty easy, from the central station T-Centralen. Just take the commuter train to Solna. However, as we are staying in Kista, we rather took the metro to Solna Centrum, and then bus 502 that leads towards Ulriksdals Station and get off at Pyramidvagen. Appointment should be made prior online, for the biometrics data, and it takes just 5 minutes. Once you have booked the appointment, it is easy to cancel or change the appointment to another date or time.

Receiving Letters
Make sure to check your names in the post boxes when you reach Kista Galleria apartments. If your name is not posted on the right post box, they will return the letter, even if the address is entered right in the post. That also means, if you want to receive a letter for someone else, they must put your name as c/o. My first receipt for the rent payments returned, as my name was not posted correctly on the postbox. So I had to ask the KTH student apartments to resend it after posting my name in the appropriate post box.

Weekly Posts
As I did from Lisbon, I hope to keep the blog updated with the information on my stay at Stockholm. This post comes with the information specific to how I reached my apartment from the airport and applied to the Swedish visa, where the "weekly posts" will follow up in the other posts. You may also like to read "The road to Lisbon", which discusses the visa application process to Lisbon.

Friday, August 30, 2013

Lisboa Love August 2013

Familiar metro stations of Lisboa..
It was August 2013, and Lisboa had started to become my second hometown, almost. That was a remarkable visit from Stockholm, and my second visit to Portugal! Thanks to Erasmus Mundus for everything!

Saturday, August 10, 2013

The next episode..

IST, Lisbon, commonly called "Tecnico"
I thought of writing this quick post answering some of the questions I often receive regarding the master studies in Europe, and specifically Erasmus Mundus (which is to be re-branded as "Erasmus+", making all similar exchange programs such as Erasmus come under the same name). 

The commonest question is, why did I pick Europe for my higher studies, instead of the US or Australia. European masters provide a nice combination of research and academics in a single master, as opposed to the complete research oriented master courses and academic master courses. Of course, the mandatory mobility of Erasmus Mundus, where we are expected to study in at least two countries during our masters is something I really liked.

Erasmus Mundus
Most of the students going to the US are going for their PhD. They get funded mostly by being a research assistant or teaching assistant. IMO, it is hard for a student to get a scholarship for masters in the US. There are research masters in Canada and the US, with similar paid research assistantship. However, Erasmus Mundus is a scholarship. You are not expected to be an assistant. You just study. The monthly allowance of 1000 Euro is pretty much enough to cover the stay in Europe, along with the travel allowances for travelling home and installation (4000 Euro/year).

ISCTE-IUL, a public university in Lisbon
Most of the PhD programs in the Europe require you to have a masters, where you can directly apply to be a PhD student in the US and Australia. Though I had a goal of pursuing a doctorate, I wanted to work for a year or two immediately following my masters. Hence European master gave me a better option, than applying for a 5 year long program of the US, which covers the MSc+PhD (Australia seems to provide the fastest, with just 3 years for the combination). European doctorate programs such as Erasmus Mundus Joint Doctorate programs have a period of 4 years.

A break?
Should we apply to the higher studies immediately after graduating from our bachelors? It depends on your personal profile. I mean, if you have a good experience, have published papers, very good GPA, you can apply immediately after the bachelors. Otherwise, better to gain some experience. Just to note that these scholarships are competitive. In my opinion, working somewhere before going abroad for higher studies is advantageous, as it gives you some exposure outside your friend circle. Nevertheless, these are just my personal opinions, and I have met many professors and scholars who would advice to go for higher studies, immediately following the bachelors, to keep up with the momentum.

See you soon!
Time has surely gone fast for me. Completing one academic year as well as the summer vacation, getting ready for the second (and final) year of my masters. Life is getting more exciting and faster. One thing I learned during these days was that life is not a destination or reaching the destinations; but a continuous journey. With that positive note, I am getting back to my world, hoping to come up with something more useful or (and?) interesting soon. ^_^

Tuesday, August 6, 2013

Moments with Twitter - III

After a few months, I did another round of tweet analysis, on my own tweets. I have shared quite a few interesting links, over the past couple of months. Also have a look at Moments with Twitter.. and Moments with Twitter - II to see some of my previous tweets.

Agia PDF Search is a useful search site that lets you search and read the PDF documents online. Oct 15, 2012

Just enter your academic email address to increase the space in your existing #Dropbox account by 3 GB or more https://t.co/GPKJrJPu Oct 15, 2012
Dropbox is interesting, and their business model is even more interesting! All the students love Dropbox, which is mostly a free cloud storage system, though paid premium packages are available.

End of Day Light Saving Time!
DST started on Sun, 25 March, 01:00 local standard time; Ends on Sun, 28 Oct, 02:00 local daylight time - http://t.co/prM3aRj4 Back to GMT. Oct 21, 2012
From the coming Sunday onwards, we will be back from the natural time, from the daylight saving time. This will make Portugal to go with GMT, and this will make the time difference with Sri Lanka, -05:30.

Changed my #twitter profile picture for the first time, since I created the account. Almost 4 years, and I didn't change much though. ;) Nov 02, 2012
Changing the profile pictures and the short bio in these profiles are becoming a harder task considering the ever increasing online presence of myself in multiple social media platforms.

An interesting, yet idiot's way to grab more visitors to your blog - Write a blog post titled, Is {SOMETHING} dead? For e.g., "Is SEO Dead?" Nov 30, 2012  
Another way, Write a silly post with a numbered title, with superlatives. For e.g: 7 worst mistakes that horse owners make in the night. :D Nov 30, 2012
OK. We all have this curiosity to click that link!

The adventures of young student backpackers with Eurail passes, 1970. 1970's photos of train travels in the Europe. http://t.co/EMN3IIMk Jan 03, 2013
Student backpackers - this term probably fits the Erasmus Mundus / Erasmus students, at least in some points of our life. One of my favourite backpacking blogs is, Breakaway Backpacker.

A ҉ Y ҉ U ҉ B ҉ O ҉ W ҉ A ҉ N ҉ Mar 03, 2013
Hello, Sri Lankan Style!

Shenzhen Window of the World.. http://t.co/w9DQqOyXct Mar 11, 2013

What is my #IP? http://t.co/DPaIw2cMtB Jul 26, 2013

CHINAKNOWLEDGE - a universal guide for #China studies http://t.co/2whemOIDrw Jul 30, 2013
This is an interesting resource to learn about China, its culture, and the Chinese language. MIT OpenCourseWare too has Simplified Chinese and other Chinese courses under the foreign languages and literature section. For me, listening to Chinese songs with the lyrics written in pinyin appears easy. Everything else seems just Chinese. :D

Collection of oddities.. the odd stuff.. http://t.co/GcXkqAP7iP Aug 02, 2013
These odd stuff are interesting. Bored Panda is a similar online magazine. However, I don't find anything these articles report odd. I find the mainstream news these days more 'odd'. One news was "Vietnam to ban discussion of news on social media sites". The situation globally doesn't look nice to me. Have a look at the Press Freedom Index of 2013.

Friday, July 19, 2013

Disconnected Worlds

Walk towards the 'point' in Parque das Nações
That was the 28th of June, the late night 12.15 a.m after the Porto trip. Enjoying Dim Sum in a Cantonese restaurant in Arroios, I was thinking of the day of return to Sri Lanka, which was just a few more days ahead. It was just 10 months in Lisbon, and for many of the readers, this period may be awfully short. But I should note that these 10 months were the best part of my life, so far. My mind was empty when I came to Lisbon. I earned lots of friends during my stay, which essentially had filled my mind full of memories. One thing I liked most about Erasmus Mundus is, it had offered us an immediate set of friends. As a set of foreign students, we all had become a clique, regardless of our cultural diversity.

Staring at a fish tank
Though we are separated by the ocean, I thought, we are still connected. We are still living in a connected world. I was wondering, how horrible that we force fish and birds to live in disconnected worlds by capturing them from their natural habitats to our fish tanks and cages. Probably they will miss their loved ones, forever. Just imagine, what would happen if you are dropped at Mars with a no return journey to the Earth (refer to the Mars One initiative)! 

Reverse Cultural Shock?
A big fish in Lisbon Oceanarium
When I came to Lisbon, I was thinking, what would I feel when I return to Sri Lanka. I thought, I would be really excited. I would not really miss anyone, because I will anyway meet all my friends again at Sweden! But what happened? Lisbon was not a mere place where I studied for a few months. Rather, it redefined me. It let me see the world in another perspective. I earned more friends than I thought. The life was simple; but complicated and complex. I was happy and sad at the same time. Then I realized, I was just sad. While I was walking towards the gate after the security checking in the Lisbon airport, I realized that I am leaving my heart in Lisbon. I will be back, I said myself. Lisbon had written so much into my memory. The days in Sri Lanka introduced a reverse cultural shock to me. I knew about it; but never thought it would happen to me, myself.

Back to 2012?
In Sri Lanka, I had the chance to meet my beloved lecturers and my friends. I started to become active. I thought of writing something on my blog, since it was starting to lose its technological essence once more, as I haven't blogged on technical stuff, after the series of posts on Jikes RVM. However, all I had was the thoughts and reflections of Lisbon. I feel like I have left some of myself at Lisboa!

Living Light Weight
Before my Erasmus Mundus life, it never occurred to me that I will have to shrink my belongings to some luggage. Travelling have to be light weight, and due to the mandatory mobility involved in the Erasmus Mundus, we also have to live light-weight. This involved a decision making on what to throw and what to take back with me.

I had some free time, and I decided to review the places I visited in Lisbon. I started writing reviews at TripAdvisor, which I didn't do for almost a year. You may have a look at my reviews. Oh, I am a proud Senior Contributor of TripAdvisor. I found the blog post, "What Happens When You Live Abroad" sharing same sentiments as me on living abroad.

My friend pointed me out visitinlisbon.com recently, when I was chatting with friends from Lisbon, over the Facebook. That site is indeed useful for anyone who is travelling to Lisbon for the first time. What I like about their site is, they keep it simple. Click through the tabs, and make sure you visit this site on a later day again, as this site is pretty much new and currently being updated.

Erasmus Mundus Presentation at the University of Moratuwa

Today I gave an introductory talk to the Erasmus Mundus program for the final year students of the Department of Computer Science and Engineering of the University of Moratuwa, Sri Lanka. The presentation slides which complimented the discussion are given above, though the presentation doesn't capture much of the topics discussed in the session. I enjoyed doing the talk and the students showed great interest and involvement. 

This was a quick introduction to the Erasmus Mundus program, based on my personal experience with Erasmus Mundus after completing the first year of EMDC (European Master in Distributed Computing) at Instituto Superior Tecnico, Lisbon. My blog posts on my stay in Lisbon can be found here. Feel free to drop me a line, if you require further information on this.

Sunday, July 7, 2013

Till I see you again..

Seagulls everywhere, just like our crows!
[29/06/2013] - We wanted to pay a quick visit to the south of Portugal following the visit to Porto, as we had initially planned a few weeks back. Since we were running out of time, we just wanted to make it a day trip. Our target was Lagos. Rede Express has a direct bus to Lagos, unlike the train which goes up to Faro, and requires changing to a urban train to Lagos. The bus went from Lisboa to Lagoa, Portimao, and finally reached Lagos. It took 3 hours and 45 minutes.

Beaches of Algarve are really popular. We preferred Lagos over Faro, as Faro gets a bit overcrowded during the summer. First we had a boat trip of an hour to the caves and cliffs of the region by a small boat, starting from the Lagos beach, for 10 Euro. It offered us a picturesque view. Our initial plan was to go on a dolphin visit (which costs 25 Euro) for 1.5 hours by boat. We were feeling dizzy after the boat ride, and had to drop our plan. But we realized, had we gone by a bigger boat, we wouldn't have felt that much uncomfortable.

Cliffs of Lagos
Meia Praia
We spent the rest of the evening under the shade in Meia Praia (half beach). We had to pay 6 Euro per shade, from 4 p.m onwards. But it worths it. The beach was warm. But was full of algae, which made us avoid having a bath or swim. I never had realized that the summer in the Europe gets this hot, to 40 °C.

Finishing Touches
[30/06/2013] - This evening was a bit tiresome and full of mixed feelings. I had a lots of things to throw. I put the clothes and shoes that I don't want to take back with me into the Humana Portugal bin. I hope they will be useful to someone in need.


My last dinner before leaving Lisbon was at my most favourite Restaurante Destino of Restauradores, with some sparkling wine. I feel like, my brain had lately started to function to just a limited extend. I already started to miss Lisboa. However, I am happy that my 10 months stay in Portugal was just perfect, and had nothing to regret. I realize how fast the time has gone, since the most remarkable eve of the new year. We are now saying good bye to the first half of 2013.

This is NOT the end
[01/07/2013] - Lisbon - Week 45: This is going to be the last post on the series "Lisbon - Weekxx" till I get back to Lisbon for my thesis, end of this year. Today was not so easy. In fact, it was one of the most difficult days in my life. Many of the things are left unwritten, as they are beyond the scope of Llovizna. I feel like missing everything. The day was full of tears, that I have never experienced before. Good bye Lisboa, till I see you again!


Sao Bento Railway Station
[28/06/2013] - Lisbon - Week 44: This week was full of farewells and tears as most of us have already started leaving Portugal, finishing our first year in EMDC. This week's highlight was the visit to Oporto (better known by its Portuguese name, Porto). The trip extended from the 25th to the 27th of June.

We reached Porto - Campanha on train by the noon. We got the andante card for 3 days (72 hours), so that we can freely travel around using the buses, metro, and the funicular. We could check in by 2 pm. We reached Trindade, by metro, and started walking to Aliados, and to Sao Bento, along the yellow line of Metro, visiting all the interests on our way. It seemed like all the cultural heritages of Porto are clustered between Aliados and Sao Bento. Having the lunch at Sao Bento, we took the metro to the station Marques, and checked in at Tropical Residences. The evening trip included a visit to Jardim do Morro in the yellow line. Unlike Lisbon, the metro in Porto was sometimes sharing the roads with the traffic, as it was going on the ground at some places. This was often imposing delays in the metro journey, and slow downs, unlike the uninterrupted underground metro of Lisbon. The bright side of this was, we were able enjoy some sceneries on our way, unlike the complete darkness of Lisbon. Unlike Lisbon, and similar to Barcelona and Madrid, the metro was going from left to right, and many lines shared the same platform in many stations, making the journey a bit more complicated for the first timers.

Rio Douro
Rio Douro and Ponte Dom Luis I
The cruise on the Douro river was remarkable for the 50 minutes, for the 10 Euro paid. It also included a free tasting of a chosen port from white, rose, ruby, or tawny, in a port cellars in Vila Nova de Gaia. We went towards Taylor's, which is one of the most popular ports. However, it was closed when we reached, as they close by 6 pm, except for the restaurant. We walked to the other side (Porto/Sao Bento side) of the Douro River from the Gaia side (down from Jardim Do Morro), by walking over the lower deck of the Ponte Dom Luis1 bridge. The upper deck holds the metro line, where the lower deck accommodates the pedestrians and the traffic. Though Ribeira looks beautiful by the river from Jardim do Morro, the dinner was not that extra-ordinary. We have had much better in Lisbon for the same price. Since the funicular that connects Batalha top of the hill with the river side Ribeira, had already stopped when we returned, we had to climb ourselves, which was not that easy, considering the vertical path.

Matosinhos Beach
Seagulls in the Matosinhos Beach
The second day started by travelling towards Matosinhos in the blue line. Matosinhos Sul has a beautiful beach. Water was still cold, regardless of the warm summer, preventing us from having a bath or swim. However, we didn't fail to notice that many others were already in the water! After the beach we visited Casa da Musica and Bolhao. We had some drinks at the Majestic Cafe, one of the oldest cafes in Porto. We paid a quick visit to the Dragon Stadium (Estadio do Dragao). We did some window shopping at Boa Vista, which is full of shopping centres. Many of the shops were having good discounts, and from the first look, it seems we could even buy some clothes back home. Realizing the weight limit imposed on us by the flight carriers, I decided not to buy anything but food and drinks to consume at the moment. Since we had explored the yellow line on the first day and the blue line on the second day, we decided to explore the red, orange, violet, and green lines on the third day, which is supposed to be our last day in Lisbon. We noted that orange line has nothing that induces our interest, and violet was just connecting the airport. Compared to green line, red line is longer, and was going towards Povoa de Varzim and Vila do Conde by the river Ave. But unfortunately, a quick check to the website of the Porto metro revealed us that there is a national strike of metro, train, and buses.

The funicular descending from Batalha
The third day had to start with an altered plan due to the strike. Metro was still running only in the city center with blue line and yellow line, with a lesser frequency. Having everything explored in the blue line, we decided to get back to the yellow line, checking out from the hotel before 1 p.m. This time we didn't miss the Funicular dos Guindais. It was interesting to travel up and down and very convenient. We sat by the river for a while, and got back to Sao Bento, visited Se, had lunch, and got back to Vila Nova de Gaia. The sun had already started to burn us. Since the train was not functioning for the day, we had to return using the Rede Expressos from Sao Bento to Sete Rios - Lisbon. Rede Expressos provides cheap tickets to the students. It was just 15 Euros, which was half the price of the train tickets in the second class, which costs 32 Euros. Though I hate strikes, I admired how the unions coordinated their strike in a national scale. We spent the rest of the time at the nearest Elcorte Ingles before returning to Lisbon. If we could compare our first day at Porto with the visit to Obidos, and the second day with Setubal, the third day was just like a visit to São Sebastião

Though we were enjoying the trip, we could not hide our tears, fearing the distance of a thousands of miles in the upcoming days. We have learned much more than Distributed Computing during our ten months of stay in Lisboa.

Friday, June 21, 2013

Lisbon - Week43

My posts at the zones, after a break!
[21/06/2013] - It has been a while since I wrote a weekly blog post on my stay at Lisbon. The last post was on Lisbon - Week29. Later I started writing fortnightly posts, or even once in three weeks, as I got busier with studies. As I have got some free time and content to write after the exams, here comes this weekly update.

Campo Pequeno
This week was full of movies, eating out, frequent drinks at the Hard Rock Cafe - Restauradores, varieties of hamburgers at h3 new hamburgology at Campo Pequeno, and some parties. I specifically enjoyed the movies at the Cinema City - Campo Pequeno. The City bar, adjoining the cinema city is very stylish and unique. It was unfortunate that I haven't watched any movies here previously, considering that Campo Pequeno is next metro station to the one close to my apartment (Saldanha), and also in a walking distance from my apartment. 

During this week, I managed to update my blog with some technical blog posts on Jikes RVM, something I researched for our AVExe group project. Most of these posts managed to get into the Architects Zone and Javalobby of DZone. I hope these posts will be of use for a bigger audience. Without the technical blog posts, recently my blog hits was facing a downfall. This helped me realize the readers of my blog.

In Sri Lanka, I have never enjoyed the cherries. It always has reminded me "Lama Panadol" (The Paracitamol brand made for the kids). However, I have started to enjoy the cherries in Lisbon. They are much fresher and sweeter here, naturally.

MMTk utility classes

Class Diagram of Counters
High Level Language Virtual Machines is a core topic of interest for the researchers who are into virtual execution environments. As an open source virtual machine released to 16 universities, as early as 2001, Jikes RVM has been a major drive for many researches. Garbage Collectors for the Jikes RVM are constructed by the framework known as the Memory Management Toolkit (MMTk). Key Compositional Elements in MMTk are utilities, policies, and plans. Apart from these, package org.mmtk.harness contains the MMTk harness test cases. Sanity checks are included in the package org.mmtk.harness.sanity. GcSanity is the collection sanity checker, that takes snapshots before and after a collection to ensure that the live objects after a collection are the same that exist before the collection. Further options are implemented in the classes of org.mmtk.harness.options. We have looked at policies and plans. In this post, we will look at the MMTk utility package, which implements the MMTk mechanisms.

MMTk comes with the utility classes that provides mechanism for the memory management, across multiple policies and plans that use those policies. An ideal example showing the usage of the utility package is, the interface
Constants. All the classes either implement the Constants interface, or are sub classes of the classes that implement the interface.

1. Allocation
The package org.mmtk.utility.alloc handles the allocation. Allocator is the base class providing the basis for the processor-local allocation. This provides the retry mechanism, to prevent the slow-path allocation causing a garbage collection, violating the assumption of uninterruptibility. Allocator also ensures that requests are aligned according to requests. This class is very crucial in garbage collection as the base class for all the allocator algorithms. Improper handling of this will make it hard to trace the bugs, where allocations may cause a garbage collection, or a garbage collection may immediately follow an allocation.

The method alignAllocation() accepts a region to be aligned, and aligns up the request, according to the requested alignment and offset, optimizing with the known alignment for the allocator algorithms. This method returns the aligned up address.

Consecutive allocation failure for the threads are counted by determineCollectionAttempts(). fillAlignmentGap() gets the start and end addresses, and fills the region with the alignment value. The minimum size guaranteeing the allocation of a given number of bytes at the specified alignment is calculated by getMaximumAlignedSize().

All allocators should use the final method,
allocSlowInline() for the slow path allocation. This method attempts the protected method allocSlowOnce() multiple times, which is defined in the subclasses. This method ensures safe execution by taking care of the thread/mutator context affinity changes, whilst allowing the collection to occur.

2. Bump Pointer Allocation
This is implemented by the BumpPointer class, which extends the abstract class Allocator. Bump Pointer scans through the allocated objects linearly. To achieve parallelism, this class maintains a header at a region of 1 or more blocks granularity. The minimum region size is 32678 bytes. Hence the 3 or 4 word overhead is less than 0.05% of all space. BumpPointer is initialized by providing the space to bump point into, indicating whether the linear scanning is allowed in the region. The method linearScan() performs a linear scan through the objects allocated by the bump pointer, and scanRegion() scans through a single contiguous region.

Intra-block allocation requires only a load, addition comparison and store, and hence is fast. The allocator will request more memory, if a block boundary is encountered. The scanned objects maintain affinity with the thread which allocated the objects in the region. This class relies on the supporting virtual machine implementing the getNextObject and related operations.

Space is allocated for a new object, by calling alloc(). This method is frequently executed, and is sensitive to the optimizing compiler. Whenever the bump pointer reaches the internal limit, allocSlow() is called. This method should never be inlined by the optimizing compiler, and hence is annotated with @NoInline, to force out of line.

Bump pointer can be re-associated to a different space by calling
rebind(), providing the new space to which the pointer to be associated to. The bump pointer will be reset such that it will use the new space for the next call to alloc().

is a stub implementation of an Address type, used by the runtime system and collector to denote the machine addresses. An allocation unit is denoted as a card, which is marked by an address that lies within the card. Providing the address of the object creating a new card, the address that lies within the card, and the size of the pending allocation in bytes, createCardAnchor() creates a record, where the start of the card is relative to the start of the object. The start of the card corresponding to the given address can be retrieved by calling getCard(). Similarly, the address of the card metadata can be retrieved by providing an address from the card, calling getCardMetaData().

Next region from the linked list of regions can be retrieved using
getNextRegion(). Similarly, setNextRegion() is used to set the next region in the linked list. clearNextRegion() clears the next region pointer in the linked list.

The DATA_END address from the region header can be retrieved using
getDataEnd(), by providing the bump pointer region address. setDataEnd() is used to set the new DATA_END address from the header. Similarly, getRegionLimit() and setRegionLimit() return or store the end address of the given region, respectively. The lowest address where the data can be stored can be retrieved by getDataStart(), for the given region. updateMetaData() is used to update the metadata, reflecting the addition of a new region. Where a bump pointer region has been consumed, but the contiguous region is available, consumeNextRegion() consumes it and returns the start of the region satisfying the outstanding allocation request.

3. Block Allocation
Blocks are a unit of storage of 2 ^ n bytes, that are non-shared (thread-local) and coarse-grained. Virtual memory resource provides virtual memory space. Here, pages consumed by blocks are accountable for the memory resource. BlockAllocator implements various sizes of Block data structure. alloc() allocates a block and returns the first usable bytes of the block. A block is freed by calling free(). If the block is completely free, the block is returned to the virtual memory resource. Otherwise, if the block is just a sub-page block, the block is added to the free list.

4. GCspy Integration
GCspy 2.0 is a tool that helps to analyse the heap, that often is used to understand the memory usage and effectiveness of garbage collectors in our project. The development of GCspy however lags behind that of the Jikes RVM core [10]. The data for GCspy is gathered using gcspyGatherData() in the classes. The package org.mmtk.utility.gcspy contains the classes for the GCspy integration, and org.mmtk.utility.gcspy.drivers contains the GCspy drivers for the MMTk collectors.

5. Treadmill
Each instance of the Treadmill is a doubly linked list, where each node is a piece of memory. The words of each node,
[Forward Link | Backward Link | Treadmill | Payload ----->]
The Treadmill object must not be moved. Depending on the constructor argument, access to the instances may be synchronized.
This assumes that the implementation language, and the language being implemented are the same. This works well with Jikes RVM, as these are Java. However, for using with other VM implementations in other languages, the doubly linked list class, upon which Treadmill depends, should be rewritten.
If the created instance is to be shared between the threads, which is decided by the boolean parameter “shared” provided as a parameter in the constructor, the access will be synchronized with locks. A node is added to the treadmill during the allocation, using addToTreadmill().

6. Large Object Allocation
This is implemented in LargeObjectLocal, which extends the abstract class LargeObjectAllocator. Each instance provides a fast unsynchronized access to the treadmill, and bound to a single CPU. Hence this should not be shared across different CPUs, as they provide truly concurrent threads.
Given c CPUs, and t Treadmill spaces, there will be c * t instances of this class, for each {CPU, Treadmill} pair.

7. Page Resource
Allocation of pages for a space is managed by the abstract class PageResource. When a space request a page, page budget and the use of virtual address space are checked. If the request can not be satisfied, garbage collection is triggered. MonotonePageResource, which is a subclass of this class handles the monotonic space usage. Similarly, the other sub class, FreeListPageResource handles the ad hoc usage. Copying collectors allocate space monotonically before freeing the entire space. Hence, MonotonePageResource is useful for them. Though the MonotonePageResource is more restrictive, it is easier to manage.

8. Heap Growth Management
HeapGrowthManager observes the heap utilization and GC load, and grows and shrinks the heap size accordingly. This class, and all the other classes in the package org.mmtk.utility.heap contains the heap related mechanisms.

9. Sanity Checker
Sanity checks for the simple collectors are handled by the classes in the package org.mmtk.utility.sanitychecker. SanityChecker is the major class handling the sanity checking. SanityDataTable implements a simple hashtable to store and retrieve per object information on sanity checks.

10. Statistics
The package org.mmtk.utility.statistics contains a number of counters, implementing the abstract class Counter for multiple counting purposes. SizeCounter, aggregates two EventCounter objects, to count the number of events and the volume. Xml class writes the output in XML format.

11. Deque
Classes extending Deque
The package org.mmtk.utility.deque defines the doubly-linked, double-ended queue (deque). Though the double linking slightly increases the space demand, this is a worth trade off, as this provides an efficient buffer and operations such as sorting.
LocalSSB implements a local unsynchronized sequential store buffer. This is used in critical code such as garbage collection work queue and the write buffer used by many collectors. Hence, this is implemented as efficient as possible in space and time. Each instance has a bump pointer and a pointer to the sharedDeque. This class follows FIFO, though it doesn't implement dequeing. TraceBuffer supports enqueuing and dequeuing of tracing data and bulk processing of the buffer.
12. Log
Log class is used for trace and error logging. Message buffer size is intentionally kept large (3000 characters), as Lock class of Jikes RVM logs a considerable amount of information during a potential GC deadlock.