[ZCM] [ZC] 1718/ 4 Comment "Persistence versus __del__"

[Collector: Zope Bugs, Features, and Patches ...]

Issue #1718 Update (Comment) "Persistence versus __del__"
 Status Pending, Database/bug medium
To followup, visit:
  http://www.zope.org/Collectors/Zope/1718

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= Comment - Entry #4 by tim_one on Mar 7, 2005 5:08 pm


Uploaded:  "deadlock.py"
 - http://www.zope.org/Collectors/Zope/1718/deadlock.py/view
The attached deadlocks reliably (ZODB 3.2.6b1).  Alas, while it uses a __del__ method to do so, it's on a non-persistent object:  the potential problems are worse than just persistent classes with __del__.
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= Comment - Entry #3 by efge on Mar 7, 2005 8:45 am

The March thread continues at
http://mail.zope.org/pipermail/zodb-dev/2005-March/008529.html

For the record I'll paste the traceback here:

  File "/opt/zope/lib/python/ZPublisher/Publish.py", line 92, in publish
    object=request.traverse(path, validated_hook=validated_hook)
  File "/opt/zope/lib/python/ZPublisher/BaseRequest.py", line 231, in traverse
    object=object.__bobo_traverse__(request)
  File "/opt/zope/lib/python/ZODB/ZApplication.py", line 48, in __bobo_traverse__
    conn=db.open(version)
  File "/opt/zope/lib/python/ZODB/DB.py", line 504, in open
    c._setDB(self)
  File "/opt/zope/lib/python/Products/ZODBMountPoint/Mount.py", line 180, in _setDB
    conn._setDB(conn._db)
  File "/opt/zope/lib/python/Products/ZODBMountPoint/Mount.py", line 176, in _setDB
    self._real_setDB(odb)
  File "/opt/zope/lib/python/ZODB/Connection.py", line 257, in _setDB
    self._flush_invalidations()
  File "/opt/zope/lib/python/ZODB/Connection.py", line 552, in _flush_invalidations
    self._cache.invalidate(self._invalidated)
  File "/appli/zeo/zeocli-192.168.106.6-8080/Products/DICOD/DICODMailingList.py", line 125, in __del__
  File "/opt/zope/lib/python/ZODB/Connection.py", line 599, in setstate
    invalid = self._is_invalidated(obj)
  File "/opt/zope/lib/python/ZODB/Connection.py", line 617, in _is_invalidated
    self._inv_lock.acquire()

The __del__ method at line 125 basically just does
  foo = self.foo


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= Edit - Entry #2 by tim_one on Mar 3, 2005 3:40 pm

 Changes: revised title, new comment

Repaired typo in Title.
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= Request - Entry #1 by tim_one on Mar 3, 2005 3:36 pm

If a persistent object has a __del__ method, bad things can happen.  The combination probably ought to be disallowed upon an attempt to create a persistent class with a __del__ method.  More info in this thread:

<http://mail.zope.org/pipermail/zodb-dev/2005-February/008522.html>

Unfortunately, that spills in to March too.
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