Merge pull request #226 from zopefoundation/sunew-failing-test-for-208

Fix KeyError on releasing resources of a Connection when closing the DB.

CHANGES.rst

@@ -5,7 +5,10 @@
 5.5.1 (unreleased)
 ==================
 
-- TBD
+- Fix KeyError on releasing resources of a Connection when closing the DB.
+  This requires at least version 2.4 of the `transaction` package.
+  See `issue 208 <https://github.com/zopefoundation/ZODB/issues/208>`.
+
 
 5.5.0 (2018-10-13)
 ==================

setup.py

@@ -72,7 +72,7 @@ def read(path):
         'persistent >= 4.4.0',
         'BTrees >= 4.2.0',
         'ZConfig',
-        'transaction >= 2.0.3',
+        'transaction >= 2.4',
         'six',
         'zc.lockfile',
         'zope.interface',

src/ZODB/Connection.py

@@ -884,7 +884,10 @@ def open(self, transaction_manager=None, delegate=True):
         """
 
         if transaction_manager is None:
-            transaction_manager = transaction.manager
+            # The .manager bit below unwraps the threaded
+            # manager so we can call unregisterSynch in close
+            # when close is called from another thread.
+            transaction_manager = transaction.manager.manager
 
         self.transaction_manager = transaction_manager
 

src/ZODB/tests/testThreadedShutdown.py

@@ -0,0 +1,55 @@
+import threading
+import time
+import unittest
+
+import ZODB
+
+
+class ZODBClientThread(threading.Thread):
+
+    def __init__(self, db, test):
+        threading.Thread.__init__(self)
+        self._exc_info = None
+        self.setDaemon(True)
+        self.db = db
+        self.test = test
+        self.event = threading.Event()
+
+    def run(self):
+        conn = self.db.open()
+        conn.sync()
+        self.event.set()
+        time.sleep(15)
+
+        # conn.close calls self.transaction_manager.unregisterSynch(self)
+        # and this succeeds.
+        conn.close()
+
+
+class ShutdownTest(ZODB.tests.util.TestCase):
+
+    def setUp(self):
+        # Our default transaction manager is
+        # transaction._manager.ThreadTransactionManager
+        # so no need to set it.
+        ZODB.tests.util.TestCase.setUp(self)
+        self._storage = ZODB.FileStorage.FileStorage(
+            'ZODBTests.fs', create=1)
+        self._db = ZODB.DB(self._storage)
+
+    def check_shutdown(self):
+        client_thread = ZODBClientThread(self._db, self)
+        client_thread.start()
+        client_thread.event.wait()
+        # calls conn._release_resources, that calls conn.close(),
+        # that calls conn.transaction_manager.unregisterSynch(self),
+        # but from a different thread, so transaction_manager._synchs
+        # have different contents.
+        self._db.close()
+
+    def tearDown(self):
+        ZODB.tests.util.TestCase.tearDown(self)
+
+
+def test_suite():
+    return unittest.makeSuite(ShutdownTest, "check")