I noticed some weird behavior with exceptions and transactions recently
(in particular, a WSGI server which relies on a __del__ to close its
client connection wasn't disconnecting from the client immediately when
a conflict error was raised by ZODB, but would indeed disconnect if a
conflict error had not been raised).
I tracked this down to the zope transaction module leaking frame stacks
via retrieving traceback objects from sys.exc_info() without
subsequently removing them from local scope.
With the attached patch, the issue was solved. If no one complains,
I'll apply it to the transaction trunk.
- C
Index: transaction/_transaction.py
===================================================================
--- transaction/_transaction.py (revision 116336)
+++ transaction/_transaction.py (working copy)
@@ -329,9 +329,15 @@
self._commitResources()
self.status = Status.COMMITTED
except:
- t, v, tb = self._saveAndGetCommitishError()
- self._callAfterCommitHooks(status=False)
- raise t, v, tb
+ t = None
+ v = None
+ tb = None
+ try:
+ t, v, tb = self._saveAndGetCommitishError()
+ self._callAfterCommitHooks(status=False)
+ raise t, v, tb
+ finally:
+ del t, v, tb
else:
if self._manager:
self._manager.free(self)
@@ -343,14 +349,18 @@
self.status = Status.COMMITFAILED
# Save the traceback for TransactionFailedError.
ft = self._failure_traceback = StringIO()
- t, v, tb = sys.exc_info()
- # Record how we got into commit().
- traceback.print_stack(sys._getframe(1), None, ft)
- # Append the stack entries from here down to the exception.
- traceback.print_tb(tb, None, ft)
- # Append the exception type and value.
- ft.writelines(traceback.format_exception_only(t, v))
- return t, v, tb
+ try:
+ t, v, tb = sys.exc_info()
+ # Record how we got into commit().
+ traceback.print_stack(sys._getframe(1), None, ft)
+ # Append the stack entries from here down to the exception.
+ traceback.print_tb(tb, None, ft)
+ # Append the exception type and value.
+ ft.writelines(traceback.format_exception_only(t, v))
+ return t, v, tb
+ finally:
+ del t, v, tb
+
def _saveAndRaiseCommitishError(self):
t, v, tb = self._saveAndGetCommitishError()
@@ -442,10 +452,13 @@
# to revert the changes in each of the resource managers.
t, v, tb = sys.exc_info()
try:
- self._cleanup(L)
+ try:
+ self._cleanup(L)
+ finally:
+ self._synchronizers.map(lambda s: s.afterCompletion(self))
+ raise t, v, tb
finally:
- self._synchronizers.map(lambda s: s.afterCompletion(self))
- raise t, v, tb
+ del t, v, tb
def _cleanup(self, L):
# Called when an exception occurs during tpc_vote or tpc_finish.
@@ -469,26 +482,33 @@
self._synchronizers.map(lambda s: s.beforeCompletion(self))
- tb = None
- for rm in self._resources:
- try:
- rm.abort(self)
- except:
- if tb is None:
- t, v, tb = sys.exc_info()
- self.log.error("Failed to abort resource manager: %s",
- rm, exc_info=sys.exc_info())
+ try:
- if self._manager:
- self._manager.free(self)
+ t = None
+ v = None
+ tb = None
+
+ for rm in self._resources:
+ try:
+ rm.abort(self)
+ except:
+ if tb is None:
+ t, v, tb = sys.exc_info()
+ self.log.error("Failed to abort resource manager: %s",
+ rm, exc_info=sys.exc_info())
- self._synchronizers.map(lambda s: s.afterCompletion(self))
+ if self._manager:
+ self._manager.free(self)
- self.log.debug("abort")
+ self._synchronizers.map(lambda s: s.afterCompletion(self))
- if tb is not None:
- raise t, v, tb
+ self.log.debug("abort")
+ if tb is not None:
+ raise t, v, tb
+ finally:
+ del t, v, tb
+
def note(self, text):
text = text.strip()
if self.description:
@@ -542,20 +562,26 @@
self.manager.tpc_vote(txn)
def abort(self, txn):
+ t = None
+ v = None
tb = None
- for o in self.objects:
- try:
- self.manager.abort(o, txn)
- except:
- # Capture the first exception and re-raise it after
- # aborting all the other objects.
- if tb is None:
- t, v, tb = sys.exc_info()
- txn.log.error("Failed to abort object: %s",
- object_hint(o), exc_info=sys.exc_info())
- if tb is not None:
- raise t, v, tb
+ try:
+ for o in self.objects:
+ try:
+ self.manager.abort(o, txn)
+ except:
+ # Capture the first exception and re-raise it after
+ # aborting all the other objects.
+ if tb is None:
+ t, v, tb = sys.exc_info()
+ txn.log.error("Failed to abort object: %s",
+ object_hint(o), exc_info=sys.exc_info())
+ if tb is not None:
+ raise t, v, tb
+ finally:
+ del t, v, tb
+
def rm_cmp(rm1, rm2):
return cmp(rm1.sortKey(), rm2.sortKey())
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