From 45a78f906d2d5fe5381d78466b11763fc56d57ba Mon Sep 17 00:00:00 2001 From: Victor Stinner Date: Mon, 21 Jun 2021 13:16:18 +0200 Subject: [PATCH] bpo-44434: Don't call PyThread_exit_thread() explicitly (GH-26758) _thread.start_new_thread() no longer calls PyThread_exit_thread() explicitly at the thread exit, the call was redundant. On Linux with the glibc, pthread_cancel() loads dynamically the libgcc_s.so.1 library. dlopen() can fail if there is no more available file descriptor to open the file. In this case, the process aborts with the error message: "libgcc_s.so.1 must be installed for pthread_cancel to work" pthread_cancel() unwinds back to the thread's wrapping function that calls the thread entry point. The unwind function is dynamically loaded from the libgcc_s library since it is tightly coupled to the C compiler (GCC). The unwinder depends on DWARF, the compiler generates DWARF, so the unwinder belongs to the compiler. Thanks Florian Weimer and Carlos O'Donell for their help on investigating this issue. --- .../next/Library/2021-06-16-16-52-14.bpo-44434.SQS4Pg.rst | 4 ++++ Modules/_threadmodule.c | 4 +++- 2 files changed, 7 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/Library/2021-06-16-16-52-14.bpo-44434.SQS4Pg.rst diff --git a/Misc/NEWS.d/next/Library/2021-06-16-16-52-14.bpo-44434.SQS4Pg.rst b/Misc/NEWS.d/next/Library/2021-06-16-16-52-14.bpo-44434.SQS4Pg.rst new file mode 100644 index 00000000000000..37b5b57ce65693 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2021-06-16-16-52-14.bpo-44434.SQS4Pg.rst @@ -0,0 +1,4 @@ +_thread.start_new_thread() no longer calls PyThread_exit_thread() explicitly +at the thread exit, the call was redundant. On Linux with the glibc, +pthread_exit() aborts the whole process if dlopen() fails to open +libgcc_s.so file (ex: EMFILE error). Patch by Victor Stinner. diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c index bee69f2099c0e8..5b5d2c5b03ec3f 100644 --- a/Modules/_threadmodule.c +++ b/Modules/_threadmodule.c @@ -1110,7 +1110,9 @@ thread_run(void *boot_raw) PyThreadState_Clear(tstate); _PyThreadState_DeleteCurrent(tstate); - PyThread_exit_thread(); + // bpo-44434: Don't call explicitly PyThread_exit_thread(). On Linux with + // the glibc, pthread_exit() can abort the whole process if dlopen() fails + // to open the libgcc_s.so library (ex: EMFILE error). } static PyObject *