libera/#clasp - IRC Chatlog

1:40:14 bike mmtk stuff: i'm adding some C++ functions to indicate that a block doesn't touch GC memory. If you enter such a "GC-safe" block the GC can run concurrently with your code. If you don't do that nothing will break but if a GC needs doing every thread will block until the long non-GC code is done. I don't think there's really any way to avoid this

1:40:26 bike this is basically the design used by Julia and by the JVM and CLR

2:16:20 bike trying to normalize everything has clued me in that snapshot save tries to write to lisp streams while the world is stopped

2:18:54 bike doing lisp anything while the world is stopped is pretty no bueno, i think

2:21:33 bike i guess this means it tries to write to *standard-output*, which could be bound to anything, so it could call arbitrary gray stream code.

3:35:49 drmeister I'm hitting this problem - I thought we solved this a long time ago. It's spending a lot of time in Unwind_Find_FDE

3:35:51 drmeister https://usercontent.irccloud-cdn.com/file/Y6R0XLhW/image.png

3:37:09 bike that's uh, not a very informative backtrace there

3:37:14 bike how is it outside start_thread?

3:37:25 bike is that like... the profiler calling it...?

3:38:50 drmeister I don't know. This is what it's up to on the right

3:38:52 drmeister https://usercontent.irccloud-cdn.com/file/0vAyxke2/image.png

3:40:58 drmeister I don't know what it means that it's outside start_thread

3:45:43 bike well the other stuff basically looks like lisp code, so it's probably not throwing C++ exceptions

3:45:59 bike i guess you could break on __cxa_throw to see if something is anyway somehow?

3:46:11 bike but that's so weird that i'm wondering if it's not just a profiling artifact

3:50:26 bike slow unwinds should also still be reported by cl:time

3:51:05 bike the main way they'd be happening is if you have lisp calling c++ calling lisp but with the C++ not marked CL_UNWIND_COOP(true). maybe some of those callbacks?

3:58:16 bike and then the inner lisp function throws through the C++