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From Cliff Woolley <jwool...@virginia.edu>
Subject Re: [PATCH] APR_BUCKET_INSERT_BEFORE in mod_logio.c
Date Mon, 20 Sep 2004 19:40:03 GMT
On Mon, 20 Sep 2004, Joe Schaefer wrote:

> Thanks, Cliff.  I guess I was getting confused by the
> warnings in the apr_ring.h docs.

If you can be more specific about what part confused you, I'd be happy to
rewrite said docs.  If they're confusing as they stand, it's probably my
fault anyway.  :)

>   % gdb /usr/local/apache2/bin/httpd -core
>          /home/c/apache/modperl-2.0/t/core.9055
> [...]
>   #0  0x0000002a9590b2ca in apr_bucket_free (mem=0x35b39e8)
>       at buckets/apr_buckets_alloc.c:174
>   174             apr_allocator_free(list->allocator, node->memnode);
>   (gdb) bt
>   #0  0x0000002a9590b2ca in apr_bucket_free (mem=0x35b39e8)
>       at buckets/apr_buckets_alloc.c:174

Have you tried compiling with bucket debugging enabled?

(See page 17 of my slides from last year's apachecon at
http://www.cs.virginia.edu/~jcw5q/talks/apache/apache2moddebugging.pdf for
help on how to do that.)

>   174             apr_allocator_free(list->allocator, node->memnode);
>   (gdb) p list
>   $5 = (apr_bucket_alloc_t *) 0x0

Um, that's bad.  :)  Try the bucket debugging code.  That will insert
bucket/brigade self-consistency checks and checks for double-free and the
like in a bunch of strategic locations that should help find the actual
problem rather than what you're seeing here, which I suspect is kind of a
red herring because you're probably looking at the after-effects of some
data structure corruption that happened at some point earlier.

--Cliff

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