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Hi! I was under the impression that Graal reused OpenJDK’s GC implementations - or was it only in the Graal as JIT compiler mode? Also, may I ask how do you kn

by kaba0 4y ago

Hi! I was under the impression that Graal reused OpenJDK’s GC implementations - or was it only in the Graal as JIT compiler mode? Also, may I ask how do you know so much about the topic? I would really like to one day work on OpenJDK/Graal, but I just don’t see the road ahead me.. — I’ve just started my master in CS, but I don’t feel it closing the gap at all. Surely I can read up more and more on the topic in small steps, but I would be very grateful for any guidance/pointer.

mike_hearn 4y ago
When used on HotSpot it does. Native images/SubstrateVM have their own GC written. Native Image EE can also use the G1 GC so then your native image is a mix of C++ and Java. The Graal compiler can be used in both modes. How did I learn about it - mostly by reading their papers, watching their videos and asking lots of inane questions on their Slack. Also, I happen to live around the corner from where the Graal team work so occasionally I've been able to meet them in person and ask questions then. But mostly I just followed their efforts for a long time. I got interested in Graal back before most people had heard about it, after somehow randomly encountering a discussion of TruffleRuby on Chris Seaton's blog. Then I wrote about it here: https://blog.plan99.net/graal-truffle-134d8f28fb69 https://blog.plan99.net/graal-truffle-134d8f28fb69 Most of the Graal guys came out of masters and PhD programs at JKU Linz, so the path you're on is a well trodden one. I wouldn't feel down about it. For me, how it worked was quite mysterious for a long time and then one day it clicked, and I saw the essential simplicity behind the concept.
- kaba0 4y ago
  Thank you very much for the informative answer!
- vips7L 4y ago
  I thought native-image in community mode use the serial gc? I'm guessing thats not true anymore?
grashalm 4y ago
Graal dev here. We have an internship program: https://www.graalvm.org/community/internship/ https://www.graalvm.org/community/internship/ It's not uncommon to do a CS master Thesis as part of an internship, if your university allows that. We have plenty of topics to choose from and you can also come up with your own. Good luck!
- kaba0 4y ago
  How hard is it to get accepted? I have written a toy JVM without a GC, only interpreter, but I don’t feel qualified, and I am afraid of blowing my chance (is there some limit on how often can one apply?). I’m working on adding a templated interpreter+GC version next, afterwards I might have a bit more confidence.
  - grashalm 4y ago
    I'd ask people that know you and have experience in the field for a realistic opinion (maybe a professor/assistant/phd?). It does definitely not hurt to code all kinds of systems stuff. Try to tinker with some low-level optimization problems. You should be an excellent coder too. In our case it does help to know the JVM ecosystem, including HotSpot details. And (shameless self plug), implement a Truffle language. Start here: https://www.youtube.com/watch?v=pksRrON5XfU&list=PLN193mR3JskpHtQ9hdMr7O19gfVFL6I_7&index=5 https://www.youtube.com/watch?v=pksRrON5XfU&list=PLN193mR3Js...

by kaba0 4y ago

mike_hearn 4y ago

When used on HotSpot it does. Native images/SubstrateVM have their own GC written. Native Image EE can also use the G1 GC so then your native image is a mix of C++ and Java. The Graal compiler can be used in both modes. How did I learn about it - mostly by reading their papers, watching their videos and asking lots of inane questions on their Slack. Also, I happen to live around the corner from where the Graal team work so occasionally I've been able to meet them in person and ask questions then. But mostly I just followed their efforts for a long time. I got interested in Graal back before most people had heard about it, after somehow randomly encountering a discussion of TruffleRuby on Chris Seaton's blog. Then I wrote about it here: https://blog.plan99.net/graal-truffle-134d8f28fb69 https://blog.plan99.net/graal-truffle-134d8f28fb69 Most of the Graal guys came out of masters and PhD programs at JKU Linz, so the path you're on is a well trodden one. I wouldn't feel down about it. For me, how it worked was quite mysterious for a long time and then one day it clicked, and I saw the essential simplicity behind the concept.

kaba0 4y ago
Thank you very much for the informative answer!
vips7L 4y ago
I thought native-image in community mode use the serial gc? I'm guessing thats not true anymore?

grashalm 4y ago

Graal dev here. We have an internship program: https://www.graalvm.org/community/internship/ https://www.graalvm.org/community/internship/ It's not uncommon to do a CS master Thesis as part of an internship, if your university allows that. We have plenty of topics to choose from and you can also come up with your own. Good luck!

kaba0 4y ago
How hard is it to get accepted? I have written a toy JVM without a GC, only interpreter, but I don’t feel qualified, and I am afraid of blowing my chance (is there some limit on how often can one apply?). I’m working on adding a templated interpreter+GC version next, afterwards I might have a bit more confidence.
- grashalm 4y ago
  I'd ask people that know you and have experience in the field for a realistic opinion (maybe a professor/assistant/phd?). It does definitely not hurt to code all kinds of systems stuff. Try to tinker with some low-level optimization problems. You should be an excellent coder too. In our case it does help to know the JVM ecosystem, including HotSpot details. And (shameless self plug), implement a Truffle language. Start here: https://www.youtube.com/watch?v=pksRrON5XfU&list=PLN193mR3JskpHtQ9hdMr7O19gfVFL6I_7&index=5 https://www.youtube.com/watch?v=pksRrON5XfU&list=PLN193mR3Js...