New submission from Zsolt Cserna <zsolt.cse...@morganstanley.com>: Python 2.6.4 (r264:75706, Oct 29 2009, 12:00:12) [C] on sunos5
On my sunos5 system if I call os.fork() in a thread created by thread.start_new_thread(), it raises RuntimeError with the message 'not holding the import lock'. It's a vanilla python compiled on sunos5 with suncc. In 2.6.3 it's ok, I think this issue is caused by patch located at http://codereview.appspot.com/96125/show. The problem can be re-produced by running the script attached. I've looked into the source and it seems to me the following: Based on the the change above, it calls fork1() system call between a lock-release calls: 3635 » _PyImport_AcquireLock(); 3636 » pid = fork1(); 3637 » result = _PyImport_ReleaseLock(); _PyImport_ReleaseLock is called in both the child and parent. Digging more into the code, _PyImport_ReleaseLock starts with the following: long me = PyThread_get_thread_ident(); if (me == -1 || import_lock == NULL) return 0; /* Too bad */ if (import_lock_thread != me) return -1; In the above code, if I interpret correctly, it compares the result of the current thread id returned by PyThread_get_thread_ident call with the thread id of the thread holding the lock - if it's different then the current thread cannot release the lock because it's not owned by it. Based on my results on solaris the 'me' variable will be different in the parent and in the child (in parent it remains the same) - resulting that the child thinks that it's not holding the release lock. I'm using pthreads on both linux and solaris. On linux the code above is working fine, but on solaris it behaves differently. ---------- components: Library (Lib) files: thread_test.py messages: 94701 nosy: csernazs severity: normal status: open title: Forking in a thread raises RuntimeError type: behavior versions: Python 2.6 Added file: http://bugs.python.org/file15232/thread_test.py _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue7242> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
