Re: multiple threads inserting into the same table

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)