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From Stas Bekman <s...@stason.org>
Subject Re: [mp2] protocol/echo_bbs2 on Win32
Date Thu, 01 Jul 2004 23:36:18 GMT
Philippe M. Chiasson wrote:
> 
> 
> Stas Bekman wrote:
> 
>> Joe Orton wrote:
>>
>>> On Thu, Jul 01, 2004 at 02:06:33PM -0700, Stas Bekman wrote:
>>> ...
>>>
>>>
>>>> $7 = (struct apr_bucket *) 0x1011007
>>>> (gdb) print *((*b)->list->prev)
>>>> Cannot access memory at address 0x1011007
>>>>
>>>> I don't understand why it doesn't happen on my setup which seems to 
>>>> be pretty close to philippe's one. I suppose it just so happens that 
>>>> the freed memory is still valid on my machine, due to different 
>>>> compilations.
>>>>
>>>> The problem appears to be in Apache, where some downstream filter 
>>>> decides to free the brigade, rendering $bb->cleanup useless, since 
>>>> you can't rely on $bb to be valid at all. That just sucks.
>>>
>>>
>>>
>>> Right; the thing is that currently, there really is no way to actually
>>> "free the brigade"; apr_brigade_destroy() just does an
>>> apr_brigade_cleanup() and unregisters the pool cleanup.  The brigade
>>> structure remains valid until the pool it's allocated from gets
>>> destroyed.
>>>
>>> To help track down the bug:
>>>
>>> 1) build httpd/apr* with -DAPR_BUCKET_DEBUG to enable the brigade
>>> consistency checks; this may show very quickly the problem
>>
>>
>>
>> Philippe, can you please do that? I don't get this problem so it's 
>> probably the best that you do that.
> 
> 
> Just updated to httpd 2.0.50-dev latest and recompiled with all the 
> APR_DEBUG_*
> I could fine, still same exact core dump ;(

I've never used that flag. I suppose it doesn't prevent segfaults but probably 
generates a copious diagnostics output.

-- 
__________________________________________________________________
Stas Bekman            JAm_pH ------> Just Another mod_perl Hacker
http://stason.org/     mod_perl Guide ---> http://perl.apache.org
mailto:stas@stason.org http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org   http://ticketmaster.com

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