Help!

[Mike Cantone <mc...@skarven.net>]

I have one remaining, but somewhat glaring problem. After I use my ASP 
application for a little while (not really that long actually - maybe a 
dozen transactions), the exact same user behavior seems to cause  the 
transaction to hang. The response times seem to get a bit worse and a 
bit worse until finally it changes doesn't come back. I usually end up 
  restarting the web server at this point (hard to do in production!) 
and it doesn't seem to die easily. I issue a couple of stops - sometimes 
as many as 3-4 until it reports actually being stopped. Then I clear out 
the session cache, restart and it seems fine. If I don't clear out the 
session cache, I think it predictably is still in a funky state - 
certainly much of the time it is.

I thought maybe the Reload directive I was using for development (to 
force the Perl Modules to get reloaded when they have been changed) 
might be using up a lot of memory, but commenting this out doesn't 
really seem to help things.

The application I'm testing doesn't store a lot in session though I've 
specified MLDBM for StateDB. If the session data *were* growing too 
large, is there any warning? Do I just lose session data or do I 
crash/hang? As I said though, I am using the recommended MLDBM.

P.S. This is considerably lower priority (unless it is related to the 
above somehow), but is there any difference between using IncludesDir 
directive and PerlSwitches -I directives? Advantages/disadvantages?

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Re: Help!

[Warren Young <wa...@etr-usa.com>]

Mike Cantone wrote:
> might be using up a lot of memory, 

Stop guessing and measure!  Does your platform have a top command?  You 
can use that to see CPU time and memory usage.  If not, you may have sar 
or some other system load testing utility.

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Re: Help!

[Josh Chamas <jo...@chamas.com>]

Mike Cantone wrote:
> I'm optimistic I am on the crux of solving this problem with the help of 
> some collective knowledge.
> 
> My ASP application can handle between 20-40 transactions - then it seems 
> to turn into a runaway process. The memory consumption according to top 
> is well under 1%, however the CPU for httpd goes into the high 90th 
> percentile. My application calls swish-e indexing and I found a very 
> interesting reference on the net which describes what seems to be the 
> identical problem here: http://mathforum.org/epigone/modperl/fraplahswo 
> . One of their recommendations is to put an AUTOLOAD in mod perls 
> startup.pl to see what is happening and, as was the case in the thread, 
> I can now see that lots of DESTROYs are not getting found.
> 

I would recommend looking into BSD::Resource for per process limits setting.
IF Apache::Resource has been ported to mod_perl 2.0, I would look
at that too, which wraps around BSD::Resource nicely.

> The majority of these DESTROYs however probably don't really exist, but 
> a method that can't be found that looks like a real problem is 
> Apache::Connection::fileno. Josh mentioned fixing this in some of his 
> change notes for versions of modperl that didn't support this. I don't 
> know who is looking for this method - I don't know whether it is ASP or 
> not. I am using Apache 2.0.x which doesn't allow me to use modperl 1.0 
> (seems to want Apache 1.3), so I am using modperl "2.0" - the dev 
> version. Where I can find the Apache::Connection.pm module, fileno truly 
> is not defined, but what is not clear to me is what I can do about it. 
> Moving to a 1.3 version of Apache is not an option for me - too many 
> others rely on 2.0. Any ideas?

The code that references fileno should be safe, even if it does not exist:

# Apache::ASP::Response->IsClientConnected
         my $fileno = eval { $conn->fileno };

If you really want this code to not do what its doing,
then you could define this after loading Apache::ASP:

sub Apache::ASP::Response::IsClientConnected {
   shift->{IsClientConnected} = 1;
}

And your application should work fine still regardless of whether
this is a real fix for your problem.  I am guessing that the real
root of this problem is something else, and you will find your fix
best in BSD::Resource.  Also, if you are using worker mpm, I probably
wouldn't, and would be wary of using BSD::Resource in this case.
I would stick with the prefork mpm in Apache 2.

Regards,

Josh

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Re: Help!

[Mike Cantone <mc...@skarven.net>]

I'm optimistic I am on the crux of solving this problem with the help of 
some collective knowledge.

My ASP application can handle between 20-40 transactions - then it seems 
to turn into a runaway process. The memory consumption according to top 
is well under 1%, however the CPU for httpd goes into the high 90th 
percentile. My application calls swish-e indexing and I found a very 
interesting reference on the net which describes what seems to be the 
identical problem here: http://mathforum.org/epigone/modperl/fraplahswo 
. One of their recommendations is to put an AUTOLOAD in mod perls 
startup.pl to see what is happening and, as was the case in the thread, 
I can now see that lots of DESTROYs are not getting found.

The majority of these DESTROYs however probably don't really exist, but 
a method that can't be found that looks like a real problem is 
Apache::Connection::fileno. Josh mentioned fixing this in some of his 
change notes for versions of modperl that didn't support this. I don't 
know who is looking for this method - I don't know whether it is ASP or 
not. I am using Apache 2.0.x which doesn't allow me to use modperl 1.0 
(seems to want Apache 1.3), so I am using modperl "2.0" - the dev 
version. Where I can find the Apache::Connection.pm module, fileno truly 
is not defined, but what is not clear to me is what I can do about it. 
Moving to a 1.3 version of Apache is not an option for me - too many 
others rely on 2.0. Any ideas?

-Mike



Josh Chamas wrote:
> Mike Cantone wrote:
> 
>>
>> The application I'm testing doesn't store a lot in session though I've 
>> specified MLDBM for StateDB. If the session data *were* growing too 
>> large, is there any warning? Do I just lose session data or do I 
>> crash/hang? As I said though, I am using the recommended MLDBM.
>>
> 
> MLDBM is not a valid setting for StateDB.  Try DB_File or GDBM_File
> if you are storing a lot of data there, but if you are, know that it
> will slow things down considerably.
> 
> Also, heed Warren's advice on measuring, not guessing.
> 
> If you need a trace level view of Apache::ASP execution, set "PerlSetVar 
> Debug -3"
> in your httpd.conf, and restart your web server.  There should be low level
> execution traces occuring then in your apache error_log.
> 
> Regards,
> 
> Josh
> 
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Re: Help!

[Josh Chamas <jo...@chamas.com>]

Mike Cantone wrote:
>
> The application I'm testing doesn't store a lot in session though I've 
> specified MLDBM for StateDB. If the session data *were* growing too 
> large, is there any warning? Do I just lose session data or do I 
> crash/hang? As I said though, I am using the recommended MLDBM.
>

MLDBM is not a valid setting for StateDB.  Try DB_File or GDBM_File
if you are storing a lot of data there, but if you are, know that it
will slow things down considerably.

Also, heed Warren's advice on measuring, not guessing.

If you need a trace level view of Apache::ASP execution, set "PerlSetVar Debug -3"
in your httpd.conf, and restart your web server.  There should be low level
execution traces occuring then in your apache error_log.

Regards,

Josh

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