PK05830: IHS 2.0 AND HIGHER ON ALL UNIX PLATFORMS CAN HANG WHEN WRITING LOG RECS TO A PIPED LOGGER, ROTATELOGS, DURING GRACEFUL RESTART.

 Fixes are available

PK65782; 2.0.47.1: IBM HTTP Server V2.0.47 Cumulative Interim Fix
PK07831 Incompatibility between IBM HTTP Server certain GSKit levels



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 information
APAR number PK05830
Reported component name WAS HTTP SERVER
Reported component ID 5630A3603
Reported release 10A
Status CLOSED FIN
PE NoPE
HIPER NoHIPER
Special Attention NoSpecatt
Submitted date 2005-05-16
Closed date 2005-05-17
Last modified date 2005-05-17

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Modules/Macros
HTTPD          

Publications Referenced

Fix information

Applicable component levels
R00A PSN    UP
R00H PSN    UP
R003 PSN    UP
R00I PSN    UP
R00S PSN    UP
R00P PSN    UP
R10A PSN    UP
R10H PSN    UP
R103 PSN    UP
R10I PSN    UP
R10S PSN    UP
R10P PSN    UP


Document Information


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