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From: Graham Leggett <minfrin@sharp.fm>
To: dev@httpd.apache.org
In-Reply-To: <201011032128.12775.sf@sfritsch.de>
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Subject: Re: Proxy regressions
Date: Thu, 4 Nov 2010 01:57:37 +0200
References: <201011032112.06345.sf@sfritsch.de>
 <201011032128.12775.sf@sfritsch.de>


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On 03 Nov 2010, at 10:28 PM, Stefan Fritsch wrote:

> Strange, I have these problems only with prefork, not with event.
> But with event I get a segfault in the reslist cleanup code.
>
> Can somebody cross-check this?

This smelled like a pool lifetime issue, and looking closer it looked  
like we were cleaning up a brigade after we had returned the backend  
to the pool. The attached patch stops the crash, and it seems to run  
at a sensible speed again (I suspect the late cleanup of the brigade  
was sending the code into a spin). Can you give it a try?

One proxy test still fails though:

t/modules/proxy.............ok 7/15# Failed test 10 in t/modules/ 
proxy.t at line 34
t/modules/proxy.............FAILED test 10
	Failed 1/15 tests, 93.33% okay

This fails because the first bucket of the response has been corrupted:

graham-leggetts-macbook-pro-3:httpd-test minfrin$ curl http://localhost:8536/reverse/modules/cgi/nph-102.pl
sl/2.3.9-dev OpenS

I've seen this a few weeks ago and it went away, so I suspect this  
isn't proxy that's doing it. Need to dig further.

Regards,
Graham
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Index: modules/proxy/mod_proxy_http.c
===================================================================
--- modules/proxy/mod_proxy_http.c	(revision 1030656)
+++ modules/proxy/mod_proxy_http.c	(working copy)
@@ -1902,9 +1902,10 @@
 
                     /* Switch the allocator lifetime of the buckets */
                     ap_proxy_buckets_lifetime_transform(r, bb, pass_bb);
+                    apr_brigade_cleanup(bb);
 
                     /* found the last brigade? */
-                    if (APR_BUCKET_IS_EOS(APR_BRIGADE_LAST(bb))) {
+                    if (APR_BUCKET_IS_EOS(APR_BRIGADE_LAST(pass_bb))) {
 
                         /* signal that we must leave */
                         finish = TRUE;
@@ -1928,7 +1929,6 @@
                     }
 
                     /* make sure we always clean up after ourselves */
-                    apr_brigade_cleanup(bb);
                     apr_brigade_cleanup(pass_bb);
 
                 } while (!finish);

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