Hi Parrin,

> the huge mod_perl-enabled server process (with all of its system resources) 
> will be tied up until the response is completely written to the client. While 
> it might take a few milliseconds for your script to complete the request, 
> there is a chance it will be still busy for some number of seconds or even 
> minutes if the request is from a slow connection client.

Are you implying that the performance will be suffered when using 
mod_perl-enabled server processes as the front tier servers?

- xinhuan

From: Perrin Harkins <phark...@gmail.com<mailto:phark...@gmail.com>>
Date: Thursday, November 13, 2014 at 5:49 PM
To: Xinhuan Zheng <xzh...@christianbook.com<mailto:xzh...@christianbook.com>>
Cc: mod_perl list <modperl@perl.apache.org<mailto:modperl@perl.apache.org>>
Subject: Re: Disconnect database connection after idle timeout

On Thu, Nov 13, 2014 at 5:38 PM, Xinhuan Zheng 
<xzh...@christianbook.com<mailto:xzh...@christianbook.com>> wrote:
We have load balancer cache that can cache images and JavaScripts. This 
functions seems a bit duplicate.

It's not about caching. Here's a quote from that link I sent earlier:

"Another drawback of this approach is that when serving output to a client with 
a slow connection, the huge mod_perl-enabled server process (with all of its 
system resources) will be tied up until the response is completely written to 
the client. While it might take a few milliseconds for your script to complete 
the request, there is a chance it will be still busy for some number of seconds 
or even minutes if the request is from a slow connection client."

You might think everyone has fast connections now so this won't matter, but it 
does. It's especially bad if you have keep-alive on for the apache server 
running mod_perl, since that means your large mod_perl processes sit around for 
some extra time doing nothing, while holding onto their database connections. 
Install a front-end proxy, turn off keep-alive  on your mod_perl and reduce 
your max idle servers, and watch what happens.

- Perrin

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