Skip site navigation (1) Skip section navigation (2)

Re: multiple threads inserting into the same table

From: Brian Cox <brian(dot)cox(at)ca(dot)com>
To: "Tom Lane [tgl(at)sss(dot)pgh(dot)pa(dot)us]" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: multiple threads inserting into the same table
Date: 2009-03-23 20:25:52
Message-ID: 49C7F050.7030505@ca.com (view raw or flat)
Thread:
Lists: pgsql-performance
Tom Lane [tgl(at)sss(dot)pgh(dot)pa(dot)us] wrote:
> pg_stat_activity says those five threads are doing nothing except
> sitting around with open transactions.  You sure you don't have a bug on
> the application side?
> 
>                         regards, 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.

Brian


"DatabasePool.Thread1" prio=10 tid=0x27f04c00 nid=0x3b38 runnable 
[0x29e27000..0x29e281b0]
    java.lang.Thread.State: RUNNABLE
	at java.net.SocketInputStream.socketRead0(Native Method)
	at java.net.SocketInputStream.read(SocketInputStream.java:129)
	at 
org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:135)
	at 
org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:104)
	at 
org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:73)
	at org.postgresql.core.PGStream.ReceiveChar(PGStream.java:259)
	at 
org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1182)
	at 
org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:194)
	- locked <0x8975c878> (a org.postgresql.core.v3.QueryExecutorImpl)
	at 
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:451)
	at 
org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:336)
	at 
org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:282)
	at 
com.mchange.v2.c3p0.impl.NewProxyStatement.executeUpdate(NewProxyStatement.java:64)
	at 
com.timestock.tess.util.DbUtils$DatabaseInsertTask.insertObject(DbUtils.java:2265)
	at 
com.timestock.tess.util.DbUtils$DatabaseInsertTask.call(DbUtils.java:2200)
	at 
com.timestock.tess.util.DbUtils$DatabaseInsertTask.call(DbUtils.java:2157)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at 
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:619)


Responses

pgsql-performance by date

Next:From: Scott MarloweDate: 2009-03-23 20:38:52
Subject: Re: multiple threads inserting into the same table
Previous:From: Tom LaneDate: 2009-03-23 19:58:29
Subject: Re: multiple threads inserting into the same table

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group