mod_include/9473: data corruption and long (multi-second) response time w/ include virtual calls /cgi-bin which uses proxypass and the resulting server uses Pragma: no-cache

[Glenn Strauss <gs...@gluelogic.com>]

>Number:         9473
>Category:       mod_include
>Synopsis:       data corruption and long (multi-second) response time w/ include virtual calls /cgi-bin which uses proxypass and the resulting server uses Pragma: no-cache
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    apache
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   apache
>Arrival-Date:   Mon Jan 14 04:00:00 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     gs-apache@gluelogic.com
>Release:        1.3.22
>Organization:
apache
>Environment:
netspace ~ -> uname -a
Linux netspace.org 2.4.14 #2 SMP Sun Nov 25 19:42:33 EST 2001 i686 unknown
>Description:
Two Apache instances.
a) http://www.netspace.org runs with mod_include and mod_proxy
   ProxyPass /cgi-bin/utils http://perl.netspace.org/utils/
b) http://perl.netspace.org is a mod_perl server

On www.netspace.org, an .shtml file includes something like
   <!--#include virtual="/cgi-bin/utils/random_line?file=/foo/bar/baz.txt"-->

Random_file is a simple script which returns a random line from the file.
It's nice and fast.  However, when random_file sets
  $r->header_out('Pragma','no-cache');
in the Perl script, the .shtml file ends up with spurious data surrounding
the returned line from the file.  It also takes multiple seconds before
completing.  This does NOT happen when the perl server is accessed directly
as http://perl.netspace.org/utils/random_line?file=/foo/bar/baz.txt (even with
Pragma: no-cache set).  Nor does this happen when accessed as
http://www.netspace.org/utils/random_line?file=/foo/bar/baz.txt.  The problem
only occurs when called from the .shtml file part of the <!--#include virtual=
>How-To-Repeat:
please see Full Description above.

The perl script for random_line is temporarily at
  http://www.netspace.org/~gs/code/RandomLine.pm
It is pre-alpha code since it's still in testing, but it's short (160 lines
including comments)

>Fix:
My workaround is to use other non-caching header indicators.
>Release-Note:
>Audit-Trail:
>Unformatted:
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Re: mod_include/9473: data corruption and long (multi-second) response time w/ include virtual calls /cgi-bin which uses proxypass and the resulting server uses Pragma: no-cache

[Glenn <gs...@netspace.org>]

On Mon, Jan 14, 2002 at 12:00:00PM -0000, submit@bugz.apache.org wrote:
> Thank you very much for your problem report.
> It has the internal identification `mod_include/9473'.
> The individual assigned to look at your
> report is: apache. 
> 
> >Category:       mod_include
> >Responsible:    apache
> >Synopsis:       data corruption and long (multi-second) response time w/ include virtual calls /cgi-bin which uses proxypass and the resulting server uses Pragma: no-cache
> >Arrival-Date:   Mon Jan 14 04:00:00 PST 2002

As an addendum, it the problem seems to be limited to the combination of
proxypass and server-side include.  Either without the other appears to
work.

My proxy setup is as follows
  ProxyRequests Off
  NoCache *
  ProxyPass /cgi-bin/utils/ http://perl.netspace.org/utils/
and all of the above is in the global server config

-Glenn