[Python-Dev] fun threading problem

Neal Norwitz nnorwitz at gmail.com
Thu Sep 14 09:48:57 CEST 2006

On everyones favorite platform (HP-UX), the following code consistently fails:

from thread import start_new_thread, allocate_lock
from time import sleep

def bootstrap():
    from os import fork ; fork()

start_new_thread(bootstrap, ())

The error is:
Fatal Python error: Invalid thread state for this thread

This code was whittled down from test_socketserver which fails in the
same way.  It doesn't matter what value is passed to sleep as long as
it's greater than 0.  I also tried changing the sleep to a while 1:
pass and the same problem occurred.  So there isn't a huge interaction
of APIs, only:  fork, allocate_lock.acquire and start_new_thread.

HP-UX seems to be more sensitive to various threading issues.  In
Modules/_test_capimodule.c, I had to make this modification:

Index: Modules/_testcapimodule.c
--- Modules/_testcapimodule.c   (revision 51875)
+++ Modules/_testcapimodule.c   (working copy)
@@ -665,6 +665,9 @@
        PyThread_acquire_lock(thread_done, 1);  /* wait for thread to finish */

+       /* Release lock we acquired above.  This is required on HP-UX. */
+       PyThread_release_lock(thread_done);

Without that patch, there would be this error:

sem_destroy: Device busy
sem_init: Device busy
Fatal Python error: UNREF invalid object
ABORT instruction (core dumped)

Anyone have any ideas?


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