[Postgres-xl-general] Failed to get pooled connection

Aaron Jackson ajackson at revionics.com
Thu Sep 18 23:40:41 PDT 2014

Didn't see any networking issues.  And there's no cluster reconfiguration, it happened today when I happened to bring up a new client.

Andrei, good point, I didn't even think about the fact that we have datanode to datanode connections here.  Coming from PGXC, we'd multiple directly as a factor of the coordinators.  I'll try bumping the connections, but I don't think we've been even close to the connection limit.  But you never know where resources could be getting scoured from in a datanode to datanode scenario.  Good call.

From: Pavan Deolasee [pavan.deolasee at gmail.com]
Sent: Friday, September 19, 2014 12:47 AM
To: Aaron Jackson
Cc: postgres-xl-general at lists.sourceforge.net
Subject: Re: [Postgres-xl-general] Failed to get pooled connection

On Fri, Sep 19, 2014 at 3:19 AM, Aaron Jackson <ajackson at revionics.com<mailto:ajackson at revionics.com>> wrote:
Occassionally, my servers will fail with the daunting "Failed to get pooled connection" error message.  Usually, I will just restart (kick) the datanodes and coordinators to resolve the issue.  But there's no indicator about why it happens and it's frequency is so inconsistent that its just a little unnerving to see it when it happens.

Any thoughts about the root cause of this?  Anything I can look into in detail?

Do you see any networking issues here? But if restarting datanodes/coordinators resolve the error, then it looks unlikely.

Does the cluster undergo any reconfiguration?

Next time this happens, it might be worth trying to connect the datanode directly via psql (preferably from the coordinator node) and see if that works ok. I wonder if you might be hitting some limits such as open file descriptors on the datanode.

Pavan Deolasee
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