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Date: Mon, 23 Mar 2009 14:38:52 -0600
Message-ID: <dcc563d10903231338y38879310j438eb07b64593c42@mail.gmail.com>
Subject: Re: multiple threads inserting into the same table
From: Scott Marlowe <scott.marlowe@gmail.com>
To: Brian Cox <brian.cox@ca.com>
Cc: "Tom Lane [tgl@sss.pgh.pa.us]" <tgl@sss.pgh.pa.us>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
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On Mon, Mar 23, 2009 at 2:25 PM, Brian Cox <brian.cox@ca.com> wrote:
> Tom Lane [tgl@sss.pgh.pa.us] wrote:
>>
>> pg_stat_activity says those five threads are doing nothing except
>> sitting around with open transactions. =A0You sure you don't have a bug =
on
>> the application side?
>>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0regards, tom lane
>
> This is a java app. A thread dump reveals that these 5 threads are all
> asleep on a socket read to postgres (see below). DbUtils.java:2265 is:
>
> session.connection().createStatement() .executeUpdate(((DatabaseInsert)
> insertObject).getInsertStmt(session));
>
> This generates and executes a single SQL insert. Since, as you point out,
> postgres seems to think that this transaction isn't doing anything,
> it's hard to figure out what the read is doing.

Might you have a firewall that's killing the connections?  What does
netstat -an on the client side say about these connections?