PK05830: IHS 2.0 AND HIGHER ON ALL UNIX PLATFORMS CAN HANG WHEN WRITING LOG RECS TO A PIPED LOGGER, ROTATELOGS, DURING GRACEFUL RESTART. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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![]() APAR status Closed as fixed if next. Error description It appears that there is an issue where a child process can stall forever when customer does graceful restart and lots of IHS threads have to write to the rotatelogs process before they finish, but rotatelogs process exits before it reads everything that has to be written. The two httpd child processes examined have different pipe handles to the piped logger they know about, when compared with the pipe handles used by the current rotatelogs process. I reviewed the Apache PR pointed out in the PMR (http://issues.apache.org/bugzilla/show_bug.cgi?id=26467) and concur that this is what the problem looks like. The fix outlined in the PR is something I considered. The root cause of the hang is apparently that the httpd child process keeps the read handle open to the rotatelogs pipe unnecessarily. Thus when rotatelogs exits, writes to the pipe from httpd don`t fail but instead block since somebody (httpd itself) still has the read handle to the pipe open.Local fix Level 3 has provided a fix for this issue. Client is currently testing.Problem summary Customers using piped logger (rotatelogs, cronolog, etc.) and graceful restart mechanism may find that an httpd child process could hang trying to write to piped logger at time of graceful restart. The problem was caused by keeping the read handle to the pipe open in the child process. This made the write calls block instead of return an error when the piped logger exited. The pipe read handles must be closed in the child process to keep this hang from occurring.Problem conclusion Temporary fix Comments This APAR is being closed as Fixed IF Next. There is a deficiency that we currently plan to fix if there is another release.
APAR is sysrouted FROM one or more of the following: APAR is sysrouted TO one or more of the following: Modules/Macros
Publications Referenced
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Product categories: Software > Application Servers >
Distributed Application & Web Servers > IBM HTTP Server >
Runtime
Operating system(s):
Software version: 10A
Software edition:
Reference #: PK05830
IBM Group: Software Group
Modified date: May 17, 2005
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