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Re: executeQuery Locked

From: Mark Lewis <mark(dot)lewis(at)mir3(dot)com>
To: Lucas Sousa <lucas75(at)gmail(dot)com>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: executeQuery Locked
Date: 2006-07-11 17:07:43
Message-ID: 1152637663.30994.380.camel@archimedes (view raw or flat)
Thread:
Lists: pgsql-jdbc
It could possibly be a bug in the driver, but much more likely it's just
the server waiting on some normal condition.

What exactly is the query in question?  Are you running with autocommit
on or off?

-- Mark Lewis

On Tue, 2006-07-11 at 13:29 -0300, Lucas Sousa wrote:
> People, I am having a very anoying problem:
> 
> I am issuing this:
> 
>         boolean result = false;
>         Statement stm = null;
>         ResultSet rs = null;
>         try
>         {
>             stm = conn.createStatement( ResultSet.TYPE_FORWARD_ONLY,
> ResultSet.CONCUR_READ_ONLY ); 
>             stm.setQueryTimeout( timeout );            
>             rs = stm.executeQuery( sql );  <- the proccess is stopped
> here for more than half an hour
>             result = rs.next();
>         }
>         finally
>         {
>             DbUtils.closeQuietly( rs );
>             DbUtils.closeQuietly( stm );
>         }
>         return result;
> 
> 
> sql is a simple select that returns one row (if I take it and send to
> pgsql it works fine)
> timeout = 120 (seconds) / I am using a DBCP pool / I use one or more
> connection per thread (I get it inside the method and release inside
> the method) 
> 
> If I get my debbuger and interrupt the thread I see it stopped in some
> point of execution of stm.executeQuery (it seems to be waitng a
> response from the postgres server) but at the same time I go to the
> server and does not find the query itself runnning. 
> 
> It seems to me that for some (weird) reason, the query timeout is bein
> achieved without throwing any error or the postgresql driver detecting
> that. 
> 
> This is some know issue?
> It is possible that the backend is cancelling the connection by
> timeout and the driver does not notice and continues waiting for it? 
> 
> the driver I am using is postgresql-8.2dev-503.jdbc3.jar (and it
> happens the same thing with the 8.0 driver)
> 
> and the stack trace of one of such locked proccess:
> 
> Thread [zzzzzzz:12] (Suspended)
>     SocketInputStream.socketRead0(FileDescriptor, byte[], int, int,
> int) line: not available [native method]
>     SocketInputStream.read(byte[], int, int) line: not available
>     BufferedInputStream.fill() line: not available 
>     BufferedInputStream.read() line: not available
>     PGStream.ReceiveChar() line: 256
>     QueryExecutorImpl.processResults(ResultHandler, int) line: 1164
>     QueryExecutorImpl.execute(Query, ParameterList, ResultHandler,
> int, int, int) line: 190 
>     Jdbc3Statement(AbstractJdbc2Statement).execute(Query,
> ParameterList, int) line: 452
>     Jdbc3Statement(AbstractJdbc2Statement).executeWithFlags(String,
> int) line: 340
>     Jdbc3Statement(AbstractJdbc2Statement).executeQuery(String) line:
> 239 
>     DelegatingStatement.executeQuery(String) line: 205
>     xxxx() line: 580 <- this is the line in the code I sent.
>     xxxx(int) line: 504
>     xxxx(int) line: 523
>     xxxx() line: 156
>     NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line:
> not available [native method]
>     NativeMethodAccessorImpl.invoke(Object, Object[]) line: not
> available
>     DelegatingMethodAccessorImpl.invoke (Object, Object[]) line: not
> available
>     Method.invoke(Object, Object...) line: not available
>     ScheduleTaskRunner.run() line: 139
>     Thread.run() line: not available
> 
> Has anyone seen this kind of situation before? 
> 
> 

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