Thomas Munro <thomas.mu...@gmail.com> writes: > On Wed, Oct 30, 2019 at 9:25 AM Tom Lane <t...@sss.pgh.pa.us> wrote: >> What I'm inclined to do is go file a bug report saying that this >> behavior contradicts both POSIX and NetBSD's own man page, and >> see what they say about that.
> From a quick look at the relevant trees, isn't the problem here that > cpython thinks it can reserve pthread_t value -1 (or rather, that > number cast to unsigned long, which is the type it uses for its own > thread IDs): > https://github.com/python/cpython/blob/master/Include/pythread.h#L21 Possibly. A value of -1 would be quite likely to crash any other libpthread code it might be passed to, though, since it's evidently supposed to be a pointer on this implementation. Note that the point here is that libpython should get a *valid* thread ID that it can use for other purposes, independently of what the host executable did, and that we can expect that libpython's calls are not being routed to the stub implementations. I've been experimenting with that test program on other platforms, and I find that FreeBSD 11.0, OpenBSD 6.4, and Fedora 30 all return plausible-looking pointers with or without -lpthread. Interestingly, RHEL6 (glibc 2.12) acts more like NetBSD is acting: you get NULL without -lpthread and a valid pointer with it. Given the lack of other problem reports about pl/python, I surmise that the glibc implementation does manage to produce a valid pointer as soon as libpthread is loaded. Or maybe they fixed glibc far enough back that nobody has tried recent python with a glibc that worked the old way. > Further evidence that this is Python's fault is the admission in the > source code itself that it is "inherently hosed": > https://github.com/python/cpython/blob/master/Python/thread_pthread.h#L299 I'm not here to defend Python's choices in this area. I'm just observing that libpthread should produce valid results in a correctly-linked dynamically loaded library, whether or not the host executable linked libpthread. NetBSD's code is failing that test, and nobody else's is. regards, tom lane
