Troubleshooting
Problem
Intermittent performance degradation on AIX might be observed in high concurrency scenarios due to malloc heap contention.
Symptom
You might notice an overall slowdown on AIX when one or more of the following features are used during high concurrency scenarios:
- Native Encryption, including encryption of the database, transaction log files and backups
- Client/server Communication that uses SSL
- Authentication using the LDAP plug-ins when the connection to the LDAP server uses SSL
- ENCRYPT/DECRYPT_BIN/DECRYPT_CHAR built-in functions
- Db2 Text Search queries that use contains() or score()
You can check whether this issue applies to you by running:
db2sysc_PID=`db2pd -edus | awk '/db2sysc PID/{print $3}'`
procstack $db2sysc_PID > procstack.db2sysc.txt
On the collected stack dump, you might see something like the following where it is acquiring a global lock for malloc and free. The greater the number of stacks containing the global lock for malloc or free the more contention there is.
Stack:
======================
0x090000000054183C _global_lock_common + 0x4BC
0x09000000000412C8 free_y + 0x108
...
Stack:
======================
0x090000000054183C _global_lock_common + 0x4BC
0x090000000004341C malloc_y + 0x79C
...
[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"ARM Category":[{"code":"a8m500000008PmnAAE","label":"Security and Plug-Ins-\u003EEncryption"}],"ARM Case Number":"","Platform":[{"code":"PF002","label":"AIX"}],"Version":"All Version(s)"}]
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Document Information
Modified date:
01 May 2025
UID
ibm10741831