Microsoft KB Archive/159192

= XCON: MTA Shows High CPU Usage and Messages Not Delivered =

Article ID: 159192

Article Last Modified on 10/28/2006

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APPLIES TO


 * Microsoft Exchange Server 4.0 Standard Edition

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This article was previously published under Q159192



SYMPTOMS
The Microsoft Exchange message transfer agent (MTA) shows very high CPU usage and messages do not move from their queues. This high CPU usage (near 100 percent) persists for extended periods of time and is viewable using Performance Monitor. The computer running Windows NT Server and Microsoft Exchange Server may perform slowly.

To observe the MTA CPU Usage using Performance Monitor:
 * 1) Start Performance Monitor
 * 2) On the Edit menu, click Add to Chart.
 * 3) For the Object, select Process.
 * 4) For the Instance, select emsmta.
 * 5) For the Counter, select "% Processor Time."
 * 6) Click Add.

You should view the CPU usage over time to see if it persists at a high value (close to 100 percent). It can be quite normal for the MTA to run with high CPU usage, but it should not persist indefinitely. (You should analyze your systems using this technique to establish a baseline for comparison purposes.)



CAUSE
In rare cases of message corruption, the Microsoft MTA can incur high CPU overhead while processing messages with Distribution Lists. The most likely cause of this corruption is improper shutdown of the computer running Microsoft Exchange Server.



STATUS
Microsoft has confirmed this to be a problem in Microsoft Exchange version 4.0. This problem was corrected in the latest Microsoft Exchange 4.0 U.S. 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

Additional query words: hung cpu bound pegging 100% percent

Keywords: kbbug kbfix KB159192

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