XCON: Err Msg: Suspected Deadlock

• Microsoft Exchange Server, version 4.0

SYMPTOMS

The Microsoft Exchange Message Transfer Agent (MTA) is still alive but it fails to handle any additional incoming or outgoing messages via the Microsoft Exchange X.400 TCP/IP Connector. Several 9405 Event IDs appear in the Windows NT Event Log:

   Error: suspected deadlock BASE KERNEL 29 (16) and MAIN BASE 1 (16)

CAUSE

The OPVRECON semaphore and the Kernel Control Block (CB) KPSEMID semaphore are acquired in a different order by two threads, causing a deadlock. This occurs when a message for an previously freed CB is sent into Platform, due to a close race condition, while the root thread is trying to acquire the same CB for a new connection.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 4.0. This problem was corrected in the latest Microsoft Exchange Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K