A fix is available
APAR status
Closed as program error.
Error description
High CPU IN THE DIST ASID AFTER APPLY OF APAR PI99529. Customer may see higher then usual cpu in the DIST address space with APAR PI99529 applied. An error in PI99529 results in a longer then expected chain of SPME blocks in an environment that contains similar IPADDResses for Db2 clients. CPU may increase over time for the DIST address space as the chain increases becuase the search time will then increase. Example of similar ipaddresses would be as follows (more likely to see the problem with CPU): 100.1.... 100.2.... 100.3.... This example list of ipaddresses would be considered unique: 100.1... 80.2... 70.3... A system dump of Db2 will show numerous entries in systrace for EXT events which equate to DSNLQDIS+3776 This problem may occur with or without System Profile Monitoring being enabled.
Local fix
DDF stop and start are required to free the SPME blocks that have accumulated.
Problem summary
**************************************************************** * USERS AFFECTED: All Distributed Data Facility (DDF) users * * who have applied PI99529/UI58395,UI58393. * * Specifically those with remote client * * applications that access a Db2 for z/OS * * server via TCP/IP. * **************************************************************** * PROBLEM DESCRIPTION: A System Profile SPME control block * * chain erroneously accumulated excessive * * SPMEs over time after applying * * PI99529/UI58395,UI58393. This may * * result in higher CPU usage in the * * xxxxDIST address space. * **************************************************************** * RECOMMENDATION: Apply corrective PTF when it is available. * **************************************************************** Db2 System Profile Monitoring automatically collects information related to remote client applications that access Db2 via TCP/IP. An SPME control block is created for each unique IP address and stored in a hash chain. After applying PI99529/UI58395(V11),UI58393(V12), Db2 system profile logic incorrectly calculated the hash index for anchoring these SPME control blocks. As a result, over time, the hash chain (which is responsible for monitoring TCP/IP connections) accumulated an excessive number of SPME control blocks. This erroneously long chain led to longer processing time for Db2 when processing inbound TCP/IP connections because, for each connection, Db2 needs to determine if an existing SPME control block already exists or a new one is to be created. This error may ultimately cause higher CPU consumption within the xxxxDIST address space. Note: This problem can occur with or without System Profile started.
Problem conclusion
Db2 System Profile Monitoring processing has been changed to correctly calculate the hash index for storing SPME control blocks related to inbound IP addresses from remote clients.
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
PH11200
Reported component name
DB2 OS/390 & Z/
Reported component ID
5740XYR00
Reported release
C10
Status
CLOSED PER
PE
YesPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-04-18
Closed date
2019-05-29
Last modified date
2019-06-03
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI63291 UI63295
Modules/Macros
DSNLILNR
Fix information
Fixed component name
DB2 OS/390 & Z/
Fixed component ID
5740XYR00
Applicable component levels
Fix is available
Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
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Document Information
Modified date:
03 June 2019