This page is part of the larger series of blogs relating to SAP Omnichannel POS –
Admin & Operational Topics.
This page discusses about the most prominent logs which occur in the GK Application logs related to Leaked lock entries in the SAP Enqueue Server.
Issue classification:
Example Error snippet:
******************************************************************************************************************************
2018-08-16 01:26:50.047 WARN {taskExecutor-9} [N/A] [N/A ] [SapLockMonitoring] !!! There are potentially leaked locks (acquired before more than 30 minutes - lockTimeBorder=Wed Aug 16 00:56:50 UTC 2018)...
2018-08-16 01:26:50.047 WARN {taskExecutor-9} [N/A] [N/A ] [SapLockMonitoring] Please check SAP Enqueue monitoring web function for details (SAP NetWeaver Administrator - Troubleshooting/Locks)
2018-08-16 01:26:50.047 WARN {taskExecutor-9} [N/A] [N/A ] [SapLockMonitoring]
2018-08-16 01:26:50.047 WARN {taskExecutor-9} [N/A] [N/A ] [SapLockMonitoring] Lock list:
2018-08-16 01:26:50.047 WARN {taskExecutor-9} [N/A] [N/A ] [SapLockMonitoring] - LockEntry[user= Guest, owner=U2018080803095097100000................376788451, name=SDC , argument=PerformanceMonitoringAlerter_NotificationLockObject , mode=E, count=1]
2018-08-16 01:26:50.048 WARN {taskExecutor-9} [N/A] [N/A ] [SapLockMonitoring] ******************************************************************************************************************************
This warning message above clearly indicates that there are some locks in the SAP Enqueue server being held up and possibly the associated Application context / thread is not present.
Root causes could be:
- The relevant application (in the above example, it is SDC) has either crashed and started on its own, however some locks in the Enqueue Server still remained.
- The relevant application (in the above example, it is SDC) was restarted intentionally, however some locks in the Enqueue Server still remained.
Checks needed to ascertain:
- Open NWA tool and check the locks present in the SAP Enqueue Server.
- Check for old / stale locks matching the description in the logs
- If they are present and do not have any change in status, etc, then this most likely is a ghost lock.
To Solve this:
- Always ensure the cardinal rule: If this leaked lock is related to CIS (if the warning message is recorded in CIS logs), then always shutdown all GK Cluster applications first.
- And then restart CIS.
- Check from NWA tool that the Ghost (stale) locks are gone. If not Only the COMPLETE NW JAVA system restart can bring the GK Applications back to normal state
- If the leaked lock is for other GK Cluster applications, then try the following
- Restart the impacted application alone.
- Check, if the leaked locks are gone in the NWA tool.
- If not, only the COMPLETE NW JAVA system restart can bring the GK Applications back to normal state
Impact, if not acted on
- Possibly the affected application is already not functioning, depending upon the nature and the type of the lock.
- Should the Application be in a working condition, then slowly there would be a pile up of threads waiting for this specific lock, and the GK Application as well as the DB connections will be exhausted thus bringing the whole System to a halt.
To Prevent this issue:
- Always restart the complete NW Java system to avoid this contentious issue.
- If a single GK Application restart is necessary, then always check the Enqueue Server locks for any stale locks from before the restart of the particular application.
Have a look at the Blog:
SAP Omnichannel POS by GK – Admin & Operational topics, for more topics related to SAP Omnichannel POS by GK.
