Flashes (Alerts)
Abstract
When using DB2 Version 9.7 Fix Pack 6, memory is consumed quickly in the DB2 private memory when an application uses the db2readlog API to extract log records (common in replication solutions). This leads to a severe memory leak.
Content
Symptom:
DB2 Version 9.7 Fix Pack 6, private memory usage grows quickly on the DB2 server ( db2sysc or db2syscs.exe process ) when applications are initiating log read requests through the db2ReadLog API.
There may be a wide variety of symptoms such as;
- out of instance memory,
- STMM detuning,
- system paging, hangs or failover.
An example of an application using the db2readlog api is IBM® Infosphere® Replication Server (Data propagator). There maybe other IBM or 3rd party 'Log reader' type applications which also uses this API.
Cause:
The cause of the symptom is APAR IC84967 which was discovered in the initial release of 9.7.0.6 dated May 30, 2012.
Diagnosing the Problem:
To identify if you are hitting the issue:
- Verify the DB2 fix pack level by running the db2level command to check if you are using the initial image of DB2 9.7 Fix Pack 6; Informational tokens are "DB2 v9.7.0.6", "s120516"
- Check if applications use the db2readlog API to extract the LOG records. Application snapshot returns the application name. Example of applications using the db2readlog API are bg_realtime_server, asncap.
Example of Application name as seen in the application snapshot ouput:
Application name = ASNCAP.exe
- If you notice the system memory usage grows quickly, perform the following diagnosis to confirm you have encountered this issue:
Gather application snapshots and verify if "Other Memory" is high (i.e. > 10MB) and is continuing to grow. Example entry:
Memory Pool Type = Other Memory
- Current size (bytes) = 719257600
High water mark (bytes) = 720764928
Configured size (bytes) = 8539602944
Users Affected:
All server editions of DB2 Version 9.7 Fix Pack 6 (9.7.0.6) on any platform. If the fix pack was downloaded from IBM Fix Central before July 3, 2012.
Workaround:
There is no Local Fix to the issue.
Resolution:
If you already downloaded DB2 9.7 FP6 and are encountering the symptoms as described in this technote and APAR IC84967, then download the updated DB2 Version 9.7 Fix Pack 6 image that contains the fix from Fix Central. The new image has the same fix level 9.7.0.6 but a new build number of s120629 and is dated July 3, 2012.
Use the download link in the related information section.
Related Information
[{"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Component":"Operating System \/ Hardware - Memory Management","Platform":[{"code":"PF002","label":"AIX"}],"Version":"9.7","Edition":"Advanced Enterprise Server;Enterprise Server;Workgroup Server","Line of Business":{"code":"LOB10","label":"Data and AI"}}]
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Document Information
Modified date:
25 September 2022
UID
swg21600160