Flashes (Alerts)
Abstract
Liberty servers running on z/OS or stack products running with embedded Liberty for z/OS may experience a native memory leak between service levels 17.0.0.2 and 18.0.0.1.
Content
On common paths for http response flush or inbound request handling the memory obtained on these paths is not freed. This leads to a leak in 64 bit private. We have seen the leak in LE HEAPPOOL64 Cellpool 11 and 5, although this could vary depending on the request payload / bodies.
The Native Storage Leak will be seen as a gradual increase in Storage allocated to the Liberty Address Space. The growth rate is dependent on the following factors, but the key is that the Storage is never FREED once it is Obtained for these areas of storage.
The Native Storage Leak reported here can be significant with it's impact driven by several factors including (but not limited to):
- Length of time the Server has been active
- Size of the payload / message(s) in the request
- Workload Volume / Transaction Per Second (TPS)
How to determine the level of Liberty being used
The Liberty service level can be located in the messages.log file, or job output of the stack product being used.
The following command can be used to determine the Liberty service level of the stack product that you are using if the stack product does not provide the Liberty level in the messages.log or job output.
WLP_HOME/wlp/bin/productInfo version --verbose
What Doc to gather if verification is needed:
A console dump of the Liberty Server Address Space can be used to help identify what is allocated in native storage. The following is an example of the SDATA needed when obtaining the console dump.
DUMP comm=(Dump of BBOS1) XX,JOBNAME=BBOS1,SDATA=(ALLNUC,CSA,GRSQ,LPA,LSQA,PSA,RGN,SQA,SUM,SWA,TRT),END
Although any type of payload can be stored in the leaked buffer, browsing the storage seen in LEDATA may show HTTP PUT/GET requests or HTTP response data as this is one area where the memory handling is obtained, but not freed.
How to obtain the fix for standalone Liberty for z/OS
- Apply APAR PI99185 PTF UI56764 to move to 18.0.0.2 or later
- Use Installation Manager to install 18.0.0.2 or later
For stack products that embed Liberty for z/OS
- If the stack product uses z/OS Liberty Embedded provided by z/OS apply 18.0.0.3 APAR PH03024 PTF UI58657 or later
- Apply stack product maintenance that includes embedded Liberty at service level 18.0.0.2 or later
Related Information
[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSD28V","label":"WebSphere Application Server Liberty Core"},"Component":"WebSphere Application Server for z\/OS Liberty","Platform":[],"Version":"All Versions","Edition":"","Line of Business":{"code":"LOB45","label":"Automation"}}]
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Document Information
Modified date:
26 September 2022
UID
ibm10869350