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When a WebSphere MQ queue manager is ended normally, the queue manager removes the majority of the IPC resources that it was using. A small number of IPC resources remain and this is as designed: some of the IPC resources are intended to persist between queue manager restarts. The number of IPC resources remaining varies to some extent, depending on the operating conditions.End of change
Start of changeThere are some situations when a larger proportion of the IPC resources in use by a queue manager might persist after that queue manager has ended:
If applications are connected to the queue manager when it stops (perhaps because the queue manager was shut down using endmqm -i or endmqm -p), the IPC resources used by these applications might not be released.
If the queue manager ends abnormally (for example, if an operator issues the system kill command), some IPC resources might be left allocated after all queue manager processes have terminated.
In these cases, the IPC resources are not released back to the system until you restart (strmqm) or delete (dltmqm) the queue manager. End of change
Start of changeIPC resources allocated by WebSphere MQ are maintained automatically by the allocating queue managers. You are strongly recommended not to perform manual actions on or remove these IPC resources. End of change
Start of changeHowever, if it is necessary to remove IPC resources owned by mqm, follow these instructions. WebSphere MQ provides a utility to release the residual IPC resources allocated by a queue manager. This utility clears the internal queue manager state at the same time as it removes the corresponding IPC resource. Thus, this utility ensures that the queue manager state and IPC resource allocation are kept in step. To free residual IPC resources, follow these steps:End of change
Start of changeStart of change
End the queue manager and all connecting applications.
Log on as user mqm.
Type the following:
On Solaris, HP-UX, and Linux:
/opt/mqm/bin/amqiclen -x -m QMGR
/usr/mqm/bin/amqiclen -x -m QMGR
This command does not report any status. However, if some WebSphere® MQ-allocated resources could not be freed, the return code is nonzero.
Explicitly remove any remaining IPC resources that were created by user mqm.
End of change
Note: Start of changeIf a non-mqm application attempted to connect to WebSphere MQ before starting any queue managers, there might still be some WebSphere MQ IPC resources remaining even after following the above steps. These remaining resources were not created by user mqm and there is no straightforward way to reliably recognize them. However, these resources are very small and are reused when WebSphere MQ is next restarted.End of change
The following table lists the CipherSpecs supported by WebSphere MQ. Specify the CipherSpec name in the SSLCIPH property of the SVRCONN channel on the queue manager and in MQEnvironment.SSLCipherSpec
Table 1. Supported CipherSpecsCipherSpec
You have WebSphere MQ clients which connect to several different MQ servers. The MQ clients are quite frequently disconnected with rc=2009, MQRC_CONNECTION_BROKEN. The clients are able to reconnect immediately. The queue managers are running well. You see no problems when issuing 'runmqsc' commands on the server.
On the MQ server side you see the following message in the queue manager's error log, AMQERR01.LOG:
AMQ9213: A communications error for TCP/IP occurred.
EXPLANATION: An unexpected error occurred in communications.
ACTION: The return code from the TCP/IP(select) [TIMEOUT] 660 seconds call was 11 (X'B'). Record these values and tell the systems administrator.
There was a parameter recently added in your qm.ini file called ClientIdle that was set to 600 secs. This caused the client connections to end after they were idle for the specified period of time + 60 seconds. After the connection is terminated at the server, the next attempt to send a request from the client side results in rc=2009.
Resolving the problem
You can either remove the ClientIdle parameter from the Channels stanza of your qm.ini files or you can set it to a value, which is higher than you expect your clients will be idle between calls.
The default path for the qm.ini file is /var/mqm/QMGRs//
After adding the leap second in Linux on 30 June, 2012, your WebSphere MQ queue manager has many FDC files related to resource issues or constraints and they will commonly report rc=xecP_E_NO_RESOURCE. You may also see your queue manager hang or freeze or there may be high cpu. The FDC's are being generated on a daily basis and may have probes of XY348010 or XC272003 from xcsCreateThread but there could be other FDC's with different probes also.
On 30 June, the Network Time Protocol (NTP) daemon scheduled a leap second to occur at midnight, meaning that the final minute of the day was 61 seconds long. We have seen several problems with otherwise unexplainable high CPU usage on Linux systems caused by the leap second at the end of June.
WebSphere MQ does not directly make calls which experience the problem, but we do use the pthreads library (NPTL), which in turn uses futexes ("fast userspace mutexes"), which can hit this problem. Busy systems running WebSphere MQ and other products are susceptible to this problem. You can read more about the problem at these links:
This problem is solved by either applying Operating System (Linux) patches, resetting the date or rebooting the system. The resolution is dependent on your level of Linux and your environment. Please consult your Linux provider for details of the solution appropriate for your system.
As a workaround you can follow these steps
If you want to migrate to WebSphere MQ Version 7.0, complete this task.
If you migrate from a previous level of this product without first backing up your system, you cannotrevert to your previous level, so back up your system before you install WebSphere MQ Version 7.0. You can then back out the upgrade if necessary. If you back out the upgrade, however, you cannot recover any work, such as changes to messages and objects, performed by WebSphere MQ Version 7.0.
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