Hi,
On Tue, 25 Feb 2020 11:48:44 -0000 e2la...@gmail.com wrote: > Hello, > > I have successfully built Python 3.8.1 on QNX, but ran into a problem when > using 'make -j4'. The build process invariably hangs with multiple > single-threaded child processes stuck indefinitely waiting on semaphores. > These semaphores will clearly never be posted to, as the processes are all > single threaded and the semaphores are not shared with any other process. > A backtrace shows that the the offending calls come from run_at_forkers(), > which is not surprising. I consider a multi-threaded fork() to be an > ill-defined operation and my arch-nemesis... Can you post the detailed backtrace(s) somewhere? Otherwise nobody will be able to dive deeper. > 3. Any reason not to use posix_spawn() instead of fork()/exec()? While some > systems implement posix_spawn() with fork()/exec() others (at least QNX) > implements it without first creating a duplicate of the parent, making it > both more efficient and safer in a multi-threaded parent. Well, subprocess can do so in some cases: https://bugs.python.org/issue35537 I'm not sure what can prevent it here, but you're welcome to investigate. > 4. thread_pthread.h seems to go to great lengths to implement locks without > using native mutexes. Python locks are not like mutexes. They can be locked from one thread and unlocked from another, so they're more like binary semaphores. Regards Antoine. _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/UZUUWLWZSODZHBKQL257EW26JLOQCQFR/ Code of Conduct: http://python.org/psf/codeofconduct/
