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From Xinhuan Zheng <xzh...@christianbook.com>
Subject Re: Disconnect database connection after idle timeout
Date Thu, 13 Nov 2014 14:39:46 GMT
Your understanding is correct. It’s what I am looking for. However, due to the apache forking
child nature, I don’t feel comfortable using SIGALARM.

We use Apache::DBI. I would prefer having enhancement in this module. Currently the module
is implementing apache process wide global cache for db connections, which we already use.
But one missing piece in this module is to handle the TTL (time-to-live) for a cached db connection.
 If TTL were implemented, the module would have to disconnect from db connection after a pre-defined
timeout so the oracle server process could be shut down more gracefully. Would it be possible
to implement that? Or is it too hard to implement?

- xinhuan

From: Paul Silevitch <paul@silevitch.com<mailto:paul@silevitch.com>>
Date: Wednesday, November 12, 2014 at 11:53 PM
To: Xinhuan Zheng <xzheng@christianbook.com<mailto:xzheng@christianbook.com>>,
modperl <modperl@perl.apache.org<mailto:modperl@perl.apache.org>>
Subject: Re: Disconnect database connection after idle timeout

I don't fully understand your need here.  I'm going to give my best.

You could set an alarm in the cleanup handler that calls the disconnect after a specified
amount of time.  If a new request comes in, you could cancel the alarm in a postreadrequest
handler (or something early in the cycle).  To cover the race condition where the disconnect
happens right before the cancel, you could check to make sure the database connection is active
right after the cancel is called.

HTH,

Paul

On Wed, Nov 12, 2014 at 9:36 PM, Xinhuan Zheng <xzheng@christianbook.com<mailto:xzheng@christianbook.com>>
wrote:
Hello,

I am having a database connection management question. Our apache+mod_perl application initiates
a database connection request when it needs to then do data processing. Afterwards, if there
is no more requests coming to this apache process, the database connection basically will
be sitting there in idle state for quite a while until the OS TCP/IP idle timeout has reached.
At that point the database would send a message into its alert log, telling that a connection
timeout has occurred and the server process will be cleaned. I would like to figure out if
mod_perl application can implement keep-alive timeout mechanism. The mod_perl would maintain
the database connection after it finishes some processing until an idle timeout defined in
the application has reached, for example, 5 minutes. Then the mod_perl would initiate a database
disconnection request so the server process can be cleaned more gracefully. We are using Oracle
11g database. I knew in 11G oracle has implemented the connection pooling. I would think the
oracle side connection pooling would be the server side maintaining the connection idle timeout.
Would it be possible on the client side the mod_perl implement something like that? I just
don’t know which side is more appropriate and how on the client side it can implement something
like that.

Thanks,
- xinhuan


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