Yeah, I think imports inside functions are overused.
On 5/9/06, Rotem Yaari
We have been encountering several deadlocks in a threaded Python application which calls subprocess.Popen (i.e. fork()) in some of its threads.
This has occurred on Python 2.4.1 on a 2.4.27 Linux kernel.
Preliminary analysis of the hang shows that the child process blocks upon entering the execvp function, in which the import_lock is acquired due to the following line:
def _ execvpe(file, args, env=None): from errno import ENOENT, ENOTDIR ...
It is known that when forking from a pthreaded application, acquisition attempts on locks which were already locked by other threads while fork() was called will deadlock.
Due to these oddities we were wondering if it would be better to extract the above import line from the execvpe call, to prevent lock acquisition attempts in such cases.
Another workaround could be re-assigning a new lock to import_lock (such a thing is done with the global interpreter lock) at PyOS_AfterFork or pthread_atfork.
We'd appreciate any opinions you might have on the subject.
Thanks in advance,
Yair and Rotem _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/guido%40python.org
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