Bugs item #1089632, was opened at 2004-12-22 11:07 Message generated for change (Settings changed) made by loewis You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1089632&group_id=5470
Category: Python Interpreter Core Group: Python 2.3 Status: Open Resolution: None >Priority: 5 Submitted By: saravanand (saravanand) Assigned to: Nobody/Anonymous (nobody) Summary: _DummyThread() objects not freed from threading._active map Initial Comment: Problem Background: =============== I have Python Server module (long running) which accepts calls from several Python Clients over socket interface and forwards the call to a C++ component. This C++ component gives the reponses back to Python Server in a separate thread(created by C++ module) via callback. In the Python Callback implementation, the responses are sent to client in a synchronised manner using Python primitive threading.Semaphore. This Synchronisation is required as the C++ component can deliver parallel responses in different C++ threads. Here, the Python Server creates the semaphore object per client when the client request arrives (in Python thread). This same object is acquired & released in the C++ callback thread(s). Here we observed that Windows Events are getting created whenever the acquire method is executed in the Python Callback implementation in the context of C++ thread. But the same event is not freed by the Python Interpreter even after the termination of the C++ thread. Because of this, a Windows Event handles are getting leaked in the Python Server. Problem Description: ============== When we checked the Python module threading.py, we found that, every time a non-python thread (in our case C++ created thread), enters python and accessesn a primitive in threading module (eg: Semaphore, RLock), python looks for an entry for this thread in the _active map using thread ID as the Key. Since no entry exists for such C++ created threads, a _DummyThread object is created and added to the _active map for this C++ thread. For every _DummyThread object that is created, there is a corresponding Windows Event also getting created. Since this entry is never removed from the _active map even after the termination of the C++ thread ( as we could make out from the code in threading.py),for every "unique" C++ thread that enters python, a Windows Event is allocated and this manifests as continuous increase in the Handle count in my Python server ( as seen in Windows PerfMon/Task Manager). Is there a way to avoid this caching in Python Interpreter? Why cant Python remove this entry from the map when the C++ thread terminates. Or if Python can't get to know about the thread termination, should it not implement some kind of Garbage collection for the entries in this Map (especially entries for the _DummyThread objects). Does this require a correction in Python modulethreading.py? or is this caching behaviour by design? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1089632&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
