mod_php vs context: tight loop

mod_php vs context: tight loop

[Brendan Jurd]

Hello list,

I have a PHP application which generates documentation on the fly with 
context.  This has been working really well, but I am now testing 
deployment on a new server with a more recent version of context, and it 
seems to be somehow getting itself into a tight loop.

When I run texexec via the mod_php apache module, the command never 
returns, and `ps ax` shows the following:

  9709 ?        S      0:00 sh -c texexec --check 2>&1
  9710 ?        S      0:00 /bin/sh /usr/bin/texexec --check
  9711 ?        R      9:59 /usr/bin/texlua /usr/bin/mtxrun --usekpse 
--execute texexec --check

`top` shows the mtxrun process eating 99.9% CPU.  Attaching an strace to 
this process, once it is underway, shows no output.

My test script is as follows:

<?php
$result = null;
system("texexec --check 2>&1", $result);
print $result . "\n";
?>

When this same test script is run directly from the command line with 
`php5 -f test.php`, it works as expected and outputs the following:

MTXrun | kpse fallback with progname 'context' initialized in 0.01 
secondsTeXExec | current distribution: web2c
TeXExec | context source date: 2010.07.30 11:35
TeXExec | format path: . /root/.texmf-config/web2c/luatex 
/root/.texmf-var/web2c/luatex /root/texmf/web2c/luatex 
/etc/texmf/web2c/luatex /var/lib/texmf/web2c/luatex 
/usr/local/share/texmf/web2c/luatex /usr/share/texmf/web2c/luatex 
/usr/share/texmf-texlive/web2c/luatex /root/.texmf-config/web2c 
/root/.texmf-var/web2c /root/texmf/web2c /etc/texmf/web2c 
/var/lib/texmf/web2c /usr/local/share/texmf/web2c /usr/share/texmf/web2c 
/usr/share/texmf-texlive/web2c
TeXExec | start of analysis
TeXExec | end of analysis
TeXExec |
TeXExec | TeXExec | version 6.2.1 - 1997-2009 - PRAGMA ADE/POD

0

Using --timeout=30 in the arguments to texexec makes no difference; 
mtxrun nonetheless runs forever until it is signalled.

It seems that this must be down to some kind of difference in Apache's 
execution environment -- I don't see any other way to explain the same 
PHP code working in cli and failing in mod_php, even when running as the 
same user.  But what possible environmental factor could lead to mtxrun 
freaking out like this?  I'm hoping someone on this list may be able to 
point me in the right direction.

This server is a VZ instance running under proxmox, with the following 
relevant ubuntu packages installed (per the 'natty' release):

context                 2010.07.30-1
libapache2-mod-php5     5.3.5-1ubuntu7.3
apache2                 2.2.17-1ubuntu1.4


-- 
Regards,
Brendan Jurd

Software Engineer
Achieve, Corp

brendan.jurd@achievecorp.com.au

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: mod_php vs context: tight loop

[Hans Hagen]

On 25-11-2011 06:12, Brendan Jurd wrote:
> Hello list,
>
> I have a PHP application which generates documentation on the fly with
> context. This has been working really well, but I am now testing
> deployment on a new server with a more recent version of context, and it
> seems to be somehow getting itself into a tight loop.
>
> When I run texexec via the mod_php apache module, the command never
> returns, and `ps ax` shows the following:
>
> 9709 ? S 0:00 sh -c texexec --check 2>&1
> 9710 ? S 0:00 /bin/sh /usr/bin/texexec --check
> 9711 ? R 9:59 /usr/bin/texlua /usr/bin/mtxrun --usekpse --execute
> texexec --check
>
> `top` shows the mtxrun process eating 99.9% CPU. Attaching an strace to
> this process, once it is underway, shows no output.
>
> My test script is as follows:
>
> <?php
> $result = null;
> system("texexec --check 2>&1", $result);
> print $result . "\n";
> ?>
>
> When this same test script is run directly from the command line with
> `php5 -f test.php`, it works as expected and outputs the following:
>
> MTXrun | kpse fallback with progname 'context' initialized in 0.01
> secondsTeXExec | current distribution: web2c
> TeXExec | context source date: 2010.07.30 11:35
> TeXExec | format path: . /root/.texmf-config/web2c/luatex
> /root/.texmf-var/web2c/luatex /root/texmf/web2c/luatex
> /etc/texmf/web2c/luatex /var/lib/texmf/web2c/luatex
> /usr/local/share/texmf/web2c/luatex /usr/share/texmf/web2c/luatex
> /usr/share/texmf-texlive/web2c/luatex /root/.texmf-config/web2c
> /root/.texmf-var/web2c /root/texmf/web2c /etc/texmf/web2c
> /var/lib/texmf/web2c /usr/local/share/texmf/web2c /usr/share/texmf/web2c
> /usr/share/texmf-texlive/web2c
> TeXExec | start of analysis
> TeXExec | end of analysis
> TeXExec |
> TeXExec | TeXExec | version 6.2.1 - 1997-2009 - PRAGMA ADE/POD
>
> 0
>
> Using --timeout=30 in the arguments to texexec makes no difference;
> mtxrun nonetheless runs forever until it is signalled.
>
> It seems that this must be down to some kind of difference in Apache's
> execution environment -- I don't see any other way to explain the same
> PHP code working in cli and failing in mod_php, even when running as the
> same user. But what possible environmental factor could lead to mtxrun
> freaking out like this? I'm hoping someone on this list may be able to
> point me in the right direction.
>
> This server is a VZ instance running under proxmox, with the following
> relevant ubuntu packages installed (per the 'natty' release):
>
> context 2010.07.30-1
> libapache2-mod-php5 5.3.5-1ubuntu7.3
> apache2 2.2.17-1ubuntu1.4

in such cases I always run with --batch to make sure that the job itself 
cannot block

i have no clue

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: mod_php vs context: tight loop

[Brendan Jurd]

On 25/11/11 19:17, Hans Hagen wrote:
> On 25-11-2011 06:12, Brendan Jurd wrote:
>> I have a PHP application which generates documentation on the fly with
>> context. This has been working really well, but I am now testing
>> deployment on a new server with a more recent version of context, and it
>> seems to be somehow getting itself into a tight loop.
>>
> in such cases I always run with --batch to make sure that the job 
> itself cannot block
>

Hi Hans,

Thanks for the response.  I tried running with --batch and it made no 
difference to the outcome.  The mtxrun process still got jammed up in 
exactly the same manner.

Regressing to the ubuntu 'lucid' packages resolved the problem for me, 
so whatever is wrong has gone wrong somewhere in the combination of 
packages in ubuntu 'natty'.

-- 
Regards,
Brendan Jurd

Software Engineer
Achieve, Corp

brendan.jurd@achievecorp.com.au

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: mod_php vs context: tight loop

[Henning Hraban Ramm]

Am 2011-11-27 um 06:45 schrieb Brendan Jurd:

> On 25/11/11 19:17, Hans Hagen wrote:
>> On 25-11-2011 06:12, Brendan Jurd wrote:
>>> I have a PHP application which generates documentation on the fly  
>>> with
>>> context. This has been working really well, but I am now testing
>>> deployment on a new server with a more recent version of context,  
>>> and it
>>> seems to be somehow getting itself into a tight loop.

Hi Brendan,
I once had similar problems running ConTeXt (LuaTeX) behind my Django  
server (gunicorn or FCGI behind Nginx).
In my case it was some strange permissions problem of the calling  
process.
I could only avoid it by changing my process manager from daemontools  
to supervisord.

Greetlings from Lake Constance!
Hraban
---
http://www.fiee.net/texnique/
http://wiki.contextgarden.net
https://www.cacert.org (I'm an assurer)

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
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wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: [SOLVED] mod_php vs context: tight loop

[Brendan Jurd]

On 27/11/11 16:45, Brendan Jurd wrote:
> On 25/11/11 19:17, Hans Hagen wrote:
>> On 25-11-2011 06:12, Brendan Jurd wrote:
>>> I have a PHP application which generates documentation on the fly with
>>> context. This has been working really well, but I am now testing
>>> deployment on a new server with a more recent version of context, and it
>>> seems to be somehow getting itself into a tight loop.
>>>
>> in such cases I always run with --batch to make sure that the job
>> itself cannot block
>
> Thanks for the response. I tried running with --batch and it made no
> difference to the outcome. The mtxrun process still got jammed up in
> exactly the same manner.
>
> Regressing to the ubuntu 'lucid' packages resolved the problem for me,
> so whatever is wrong has gone wrong somewhere in the combination of
> packages in ubuntu 'natty'.
>

I did eventually get to the bottom of this.  Turns out that mtxrun was 
failing to find a writable cache path (from mtxrun line 9269).

To find a cache path, mtxrun searches through the environment variables 
TEXMFCACHE, TMPDIR, TEMPDIR, TMP, TEMP, HOME, HOMEPATH.

The apache worker process had no such environment variables, so mtxrun 
failed.  Once I added the following line to my PHP script, everything 
started working just fine:

putenv('TEMPDIR=/tmp');

-- 
Regards,
Brendan Jurd

Software Engineer
Achieve, Corp

brendan.jurd@achievecorp.com.au
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: [SOLVED] mod_php vs context: tight loop

[Hans Hagen]

On 2-12-2011 02:59, Brendan Jurd wrote:

> The apache worker process had no such environment variables, so mtxrun
> failed. Once I added the following line to my PHP script, everything
> started working just fine:
>
> putenv('TEMPDIR=/tmp');

can you that on the wiki? maybe we need a section: "running context in 
webservices" or so


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: [SOLVED] mod_php vs context: tight loop

[Brendan Jurd]

On 02/12/11 21:31, Hans Hagen wrote:
> On 2-12-2011 02:59, Brendan Jurd wrote:
>
>> The apache worker process had no such environment variables, so mtxrun
>> failed. Once I added the following line to my PHP script, everything
>> started working just fine:
>>
>> putenv('TEMPDIR=/tmp');
>
> can you that on the wiki? maybe we need a section: "running context in
> webservices" or so
>

I have added my findings to the wiki, as a new page.  At the moment the 
page isn't linked to from anywhere else in the wiki.  I wasn't sure 
which pages might have adjacent content.  Please feel free to relocate 
this if you don't like the name, or think it doesn't deserve its own page.

http://wiki.contextgarden.net/Running_ConTeXt_without_a_shell

BTW, congratulations on the new theme for the wiki.  It's a big improvement.

-- 
Regards,
Brendan Jurd

Software Engineer
Achieve, Corp

brendan.jurd@achievecorp.com.au
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________