More information:
The hang happens when building extensions, using the setup.py script. The
script determines that the build is parallel (build_ext.py/build_extensions)
and creates a thread pool. Each thread then executes a compilation job by
fork()ing a compiler process.
I don't see how it wor
Sorry, should have posted the backtrace from the beginning. It goes deeper than
this, but the important part is in the child after fork():
#0 SyncSemWait () at
/builds/workspace/710-SDP/build_x86_64/lib/c/kercalls/x86_64/SyncSemWait.S:37
#1 0x004bfa174ac6 in PyThread_acquire_lock_timed
(l
It's actually not clear to me what lock it is from the core file I took, as
rlock_acquire() is called through a function pointer from
method_vectorcall_VARARGS_KEYWORDS() (I posted the backtrace separately).
My suspicion is that it doesn't fail on macOS because it may keep all of the
semaphore'
A change to posix_spawnp() fixes the problem for me:
diff --git a/Lib/distutils/spawn.py b/Lib/distutils/spawn.py
index ceb94945dc..cb69de4242 100644
--- a/Lib/distutils/spawn.py
+++ b/Lib/distutils/spawn.py
@@ -90,7 +90,7 @@ def _spawn_posix(cmd, search_path=1, verbose=0,
dry
A simple example that reproduces the hang (please keep in mind that I have very
little experience writing Python code...):
import os
from concurrent.futures import ThreadPoolExecutor
def new_process(arg):
pid = os.fork()
if pid == 0:
exec_fn("/bin/true
I believe that the problem is in logging/__init__.py, which registers an
atfork() handler for re-initializing its lock. However, as part of this process
it attempts to acquire the module lock, which has not been reinitialized and so
still reflects the parent's state of the lock.
--Elad
Done.
Thanks,
--Elad
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