Re: SQL query never ends

This sort of behavior often indicates some kind of unsafe concurrent
usage of the JDBC Connection.  Is this running in a multi-threaded
environment?  If so, are there measures in place to ensure that only one
thread uses the connection at a time?

It would also be useful if you could do a thread dump while it's hanging
and send a stack trace of the affected thread.

-- Mark

On Wed, 2006-08-09 at 10:21 +0000, James Im wrote:
> I'm experimenting a random problem on my PC. Sometimes a sql query
> executed with Statement never returns. The code is blocked at a line
> like this one:
> 
> rs = stmt.executeQuery("select true");
> 
> The query is not important: it fails with any type of query, at random,
> even with the one above.
> 
> I never get an exception.
> 
> Now the logs. I've enable logging at the database level and I have set
> "statement_timeout = 3000". I have searched for the query in
> postgresql's log but I cannot find the query which is blocking in my
> java code so I guess that it means that the query never reached postgresql.
> 
> I've enabled jdbc logging with "loglevel=2" and this is what I get:
> 
> simple execute,
> handler=org.postgresql.jdbc2.AbstractJdbc2Statement$StatementResultHandler@996cca,
> maxRows=0, fetchSize=0, flags=17
> FE=> Parse(stmt=null,query="i've remove the select query",oids={})
> FE=> Bind(stmt=null,portal=null)
> FE=> Describe(portal=null)
> FE=> Execute(portal=null,limit=0)
> FE=> Sync
> 
> .. and nothing else. No "<=BE ..." follow the " FE=> Sync" log entry.
> 
> 
> I've also tried to put "stmt.setQueryTimeout(3);" but it doesn't seem to
> do anything.
> 
> I'm using postgresql 8.1.4 on Windows 2000 Pro SP4 and the driver  	is
> "8.1-407 JDBC 3". I'm also using java 1.5.0_06-b05.
> 
> 
> I guess that there is a bug in the driver. If I'm wrong, please tell me
> how to solve it. If I'm right, could you try to fix it?
> 
> _________________________________________________________________
> Log p MSN Messenger direkte p nettet:  http://webmessenger.msn.com
> 
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 1: if posting/reading through Usenet, please send an appropriate
>        subscribe-nomail command to majordomo@postgresql.org so that your
>        message can get through to the mailing list cleanly