[Netarchivesuite-devel] About the DBConnect class, running out of connections

Søren Vejrup Carlsen svc at kb.dk
Fri Mar 25 16:32:00 CET 2011


Hi Nicolas.
I believe, that we are already using "c3p0"  in the wayback module, which uses hibernate to access a simple derby database.
Look especially at the code in the package dk.netarkivet.wayback.indexer

I'm curious that you didn't get this problem until launching 3.15.1. Why can that be?

Best Regards
Søren

Fra: netarchivesuite-devel-bounces at lists.gforge.statsbiblioteket.dk [mailto:netarchivesuite-devel-bounces at lists.gforge.statsbiblioteket.dk] På vegne af Nicolas Giraud
Sendt: 25. marts 2011 16:14
Til: netarchivesuite-devel at lists.gforge.statsbiblioteket.dk
Emne: Re: [Netarchivesuite-devel] About the DBConnect class, running out of connections

The problem occurs whether the DB server is on the same machine or a remote host.

I am considering to set up a real connection pool. As we have different target systems, I'd go for c3p0 or dbcp. Do you guys have some experience with these APIs, would you recommend one? C3p0 seems really simple to put in place.

Best,

Nicolas
2011/3/25 Søren Vejrup Carlsen <svc at kb.dk<mailto:svc at kb.dk>>
Hi Nicolas.
You could be right about NAS never closing the database connections. But the connections to the database timeout automatically,
don't they?

We've had similar problems with derby in our production environment running 3.14.1.

But we didn't see in our test-environment.
Are you running the database on the same server as the processes running?

Best Regards
Søren

Fra: netarchivesuite-devel-bounces at lists.gforge.statsbiblioteket.dk<mailto:netarchivesuite-devel-bounces at lists.gforge.statsbiblioteket.dk> [mailto:netarchivesuite-devel-bounces at lists.gforge.statsbiblioteket.dk<mailto:netarchivesuite-devel-bounces at lists.gforge.statsbiblioteket.dk>] På vegne af Nicolas Giraud
Sendt: 25. marts 2011 14:57
Til: netarchivesuite-devel at lists.gforge.statsbiblioteket.dk<mailto:netarchivesuite-devel at lists.gforge.statsbiblioteket.dk>
Emne: [Netarchivesuite-devel] About the DBConnect class, running out of connections

Hi,

On our new production environment, we have run into a error where the DB has too many open connections. I've started investigating on this, by looking at the DBConnect class.

First the "connection pool" in it seems bugged, as if any Thread in the WeakHashMap is garbage collected, the associated connection might still be open and is not closed. Also I don't see anywhere in all of the code a call to Connection#close(), except in DomainDBDao#close() which by the way is never called.

Where are DB connections closed ? It seems they are never closed, unless I have completely misunderstood the code.

Any help will be greatly appreciated.

Cheers,

--
Nicolas Giraud
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Développeur Archives du Web - Bibliothèque Nationale de France
Web Archiving Developper - National Library of France
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--
Nicolas Giraud
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Développeur Archives du Web - Bibliothèque Nationale de France
Web Archiving Developper - National Library of France
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