Run two of these to provoke a deadlock on multiple storages.

src/ZEO/tests/deadlock.py

+import ZODB
+from ZODB.POSException import ConflictError
+from ZEO.ClientStorage import ClientStorage, ClientDisconnected
+from ZEO.zrpc.error import DisconnectedError
+
+import os
+import random
+import time
+
+L = range(1, 100)
+
+def main():
+    z1 = ClientStorage(('localhost', 2001), wait=1)
+    z2 = ClientStorage(('localhost', 2002), wait=2)
+    db1 = ZODB.DB(z1)
+    db2 = ZODB.DB(z2)
+    c1 = db1.open()
+    c2 = db2.open()
+    r1 = c1.root()
+    r2 = c2.root()
+
+    while 1:
+        try:
+            try:
+                update(r1, r2)
+            except ConflictError, msg:
+                print msg
+                get_transaction().abort()
+                c1.sync()
+                c2.sync()
+        except (ClientDisconnected, DisconnectedError), err:
+            print "disconnected", err
+            time.sleep(2)
+
+def update(r1, r2):
+    k1 = random.choice(L)
+    k2 = random.choice(L)
+
+    updates = [(k1, r1),
+               (k2, r2)]
+    random.shuffle(updates)
+    for key, root in updates:
+        root[key] = time.time()
+    get_transaction().commit()
+    print os.getpid(), k1, k2
+
+if __name__ == "__main__":
+    main()