APAR status
Closed as program error.
Error description
IHSDiag, The MustGather for IHS, contains a diagnostic module (mod_mpmstats) that traces the number of threads in various states as well as aggregating how many threads are busy in specific Apache modules. This latter form of tracking is enabled only when the TrackModules directive is set to "on". One particular phase of Apache processing, the "post_read_request" hook, has not been instrumented to provide the data required to identify the currently busy Apache module via "TrackModules on". If a module is hanging in this phase of processing, mod_mpmstats can only count it against the total of "reading" threads, but cannot count the thread towards the total number of threads busy in a particular modules. We have observed a number of incidents where third-party Apache modules hang in the post_read_request phase of processing, and mod_mpmstats is the best way to identify them. More info on mod_mpmstats is available at the following URL: http://publib.boulder.ibm.com/httpserv/ihsdiag/
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: Users debugging a hang with mod_mpmstats, * * using the TrackModules feature, who see large numbers of * * threads in the "rd" state but no particular modules listed * * accounting for the "rd" threads. * **************************************************************** * PROBLEM DESCRIPTION: post_read_request hook not instrumented * * of mod_mpmstats, and many third-party modules can hang in * * this phase. * **************************************************************** * RECOMMENDATION: Apply this fix, and use mod_mpmstats with * * "TrackModules on", to debug webserver hangs * **************************************************************** The phases of Apache Processing need to be explicitly instrumented to identify the name of the module being run to mod_mpmstats. The post_read_request hook was not instrumented in previous releases of IHS.
Problem conclusion
The post_read_request hook was instrumented in the same fashion as several other existing phases of Apache processing. This fix is targeted for: Fix pack 6.0.2.35 Fix pack 6.1.0.23 (n/a for 7.0 release)
Temporary fix
Comments
APAR Information
APAR number
PK76363
Reported component name
WEBS APP SERV N
Reported component ID
5724H8800
Reported release
60A
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2008-11-24
Closed date
2008-12-05
Last modified date
2008-12-05
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
WEBS APP SERV N
Fixed component ID
5724H8800
Applicable component levels
R60A PSN
UP
R60H PSN
UP
R60I PSN
UP
R60P PSN
UP
R60S PSN
UP
R60W PSN
UP
R61A PSN
UP
R61H PSN
UP
R61I PSN
UP
R61P PSN
UP
R61S PSN
UP
R61W PSN
UP
R61Z PSN
UP
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Document Information
Modified date:
10 February 2022