Bug Fixed:

  ZEO manages a separate thread for client network IO.  It created
  this thread on import, which caused problems for applications that
  implemented daemon behavior by forking.  Now, the client thread
  isn't created until needed.

src/CHANGES.txt

@@ -2,6 +2,17 @@
  Change History
 ================
 
+3.9.2 (2009-10-??)
+==================
+
+Bugs Fixed
+----------
+
+- ZEO manages a separate thread for client network IO.  It created
+  this thread on import, which caused problems for applications that
+  implemented daemon behavior by forking.  Now, the client thread
+  isn't created until needed.
+
 3.9.1 (2009-10-01)
 ==================
 

src/ZEO/tests/testZEO.py

@@ -52,6 +52,8 @@ import zope.testing.setupstack
 
 logger = logging.getLogger('ZEO.tests.testZEO')
 
+ZEO.zrpc.connection.start_client_thread()
+
 class DummyDB:
     def invalidate(self, *args):
         pass

src/ZEO/zrpc/client.py

@@ -24,12 +24,13 @@ from ZODB.loglevels import BLATHER
 
 from ZEO.zrpc.log import log
 import ZEO.zrpc.trigger
-from ZEO.zrpc.connection import ManagedClientConnection
+from ZEO.zrpc.connection import ManagedClientConnection, start_client_thread
 
 class ConnectionManager(object):
     """Keeps a connection up over time"""
 
     def __init__(self, addrs, client, tmin=1, tmax=180):
+        start_client_thread()
         self.addrlist = self._parse_addrs(addrs)
         self.client = client
         self.tmin = min(tmin, tmax)

src/ZEO/zrpc/connection.py

@@ -52,15 +52,15 @@ def client_exit():
 atexit.register(client_exit)
 
 def client_loop():
-    map = client_map
+    global client_running
+    client_running = True
+    client_exit_event.clear()
 
+    map = client_map
     read = asyncore.read
     write = asyncore.write
     _exception = asyncore._exception
     loop_failures = 0
-    client_exit_event.clear()
-    global client_running
-    client_running = True
 
     while client_running and map:
         try:
@@ -153,9 +153,19 @@ def client_loop():
 
     client_exit_event.set()
 
-client_thread = threading.Thread(target=client_loop, name=__name__)
-client_thread.setDaemon(True)
-client_thread.start()
+client_thread_lock = threading.Lock()
+client_thread = None
+def start_client_thread():
+    client_thread_lock.acquire()
+    try:
+        global client_thread
+        if client_thread is None:
+            client_thread = threading.Thread(target=client_loop, name=__name__)
+            client_thread.setDaemon(True)
+            client_thread.start()
+    finally:
+        client_thread_lock.release()
+
 #
 ##############################################################################