Wednesday, August 16, 2017

Lock-Free Memory Reclamation by Erez Petrank

I've thought about doing some talks about Lock-Free Memory Reclamation, but Erez Petrank beat me to it. Even though I know a lot about the subject, I couldn't have done a better job myself (really, I couldn't), and lucky for you, his talks are online ;)
There are actually two talks, one is about Manual Lock-Free Memory Reclamation:

The other is about Automatic Memory Reclamation sometimes called Garbage Collection:

on this second one I learned a _lot_ because although Andreia and I are working on manual reclamation stuff so we know all the details he mentioned, on GC stuff I'm a bit clueless, except for the basic stuff. Both talks are really insightful and funny.
If you're looking for accurate and deep knowledge of memory reclamation, there is nothing better out there than these talks... except maybe a long chat with Erez himself  ;)

Here's my favorite quote by Erez Petrank:
(...) There are several papers which will tell you that there are Lock-Free Garbage Collectors. Do Not trust them! Some of them don't understand what Lock-Freedom is, some of them don't understand what Garbage Collection is, and some of them understand both but do not really look at the details.
GC progress is the big thing that no one looks at. They say: "Ok sure, I don't worry about the garbage collection, I only worry about the program and that is lock-free.", which is not ok, because if the garbage collection does not complete its operation, the program can not complete its operation because it can not allocate. (...)

Thursday, August 10, 2017

What do blockchains and wait-free universal constructs have in common?

SPAA 2017 and PODC 2017 are over but what I heard there will stay with me for a long time  :)
I learned a lot, got to present a brief announcement on Hazard Eras, met in person many interesting researchers in the field, had some awesome discussions about lock-free memory reclamation, and much, much more.
Sure, most of the talks are very theoretical, not the kind of thing I would recommend a software engineer, but just to get to pick the brains of all these men and women is worth the admission price.

For those of you who were not there, Maurice Herlihy gave an amazing keynote about Blockchains and how they are related to Universal Constructs and wait-free.
I say "amazing" because Andreia and I have been working hard for the past year on a practical universal construct, so it's cool to see that there are some similarities of our research with Blockchains and Proof of Work. I even got to chat with Maurice a couple of times to get some of his insights on wait-free universal constructs versus transactional memory.
He was nice enough to put his slides online, so click the link for a small taste of what it was like to be there