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From Mark Blackman <mark.black...@db.com>
Subject RE: [users@httpd] help interpreting an Apache 2.2 segmentation fault backtrace. [I]
Date Thu, 06 Aug 2015 13:54:17 GMT
Classification: For internal use only

Thanks, it is almost certainly heap corruption, but I would need something to point the finger
at. Considering that httpd 2.2.29 is so mature, I'd be surprised if it's any httpd code. I'm
personally speculating that one of either those two modules is interfering with the allocations
of the other, but I'd like to confirm that and track it to one or the other.

We do sometimes get Abort-triggered core dumps where glibc is triggering an Abort on a 'double
free or corruption', suggesting that some of the MALLOC_CHECK_s checks are being invoked,
although the environment variable hasn't be set. I need to remedy this, so I need more than
just a statement of "heap corruption" ideally, but a specific cause and remedy.

Abort-triggered dump here:

*** glibc detected *** /apache22/bin/httpd: double free or corruption (out): 0x0bbf9568 ***
======= Backtrace: =========
/usr/lib/libc.so.6[0xf757e432]
/usr/lib/libc.so.6[0xf757fc3f]
/usr/lib/libc.so.6(__libc_free+0x84)[0xf757ff94]
/versions/apache-2.2.29/lib/libapr-1.so.0[0xf76bee3f]
/versions/apache-2.2.29/lib/libapr-1.so.0(apr_pool_destroy+0x114)[0xf76bf45f]
/versions/wlsplugins_generic_11.1.1.7.0/lib/mod_wl.so(_ZN6Reader5resetEv+0x3c)[0xf71ed9d4]
======= Memory map: ========
08048000-0827c000 r-xp 00000000 fd:04 2671007 /versions/apache-2.2.29/bin/httpd
0827c000-0828a000 rwxp 00233000 fd:04 2671007 /versions/apache-2.2.29/bin/httpd
0828a000-0bd21000 rwxp 00000000 00:00 0 [heap]


I am talking to Oracle about the Weblogic proxying module (WLS Plugin), but they've not come
up much of a diagnosis yet. This is all prefork, so it's not one thread interfering with another.

How "hard"/"common" is it for one module to screw up the pool allocation (for all the modules)
for a request?

-----Original Message-----
From: Jens-U. Mozdzen [mailto:jmozdzen@nde.ag]
Sent: 06 August 2015 13:54
To: users@httpd.apache.org
Subject: Re: [users@httpd] help interpreting an Apache 2.2 segmentation fault backtrace. [I]

...

it might be as simple as a heap corruption. Does apache22 use glibc
malloc() routines? Then you might give setting MALLOC_CHECK_ to a
non-zero value a try. OTOH, this may significantly reduce the
performance of your httpd.




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