Re: insert function runs forever if connection is lost, keeping thetable locked

Hi,

no, this is a plain JRE application which does connect via


                        Properties props = new Properties();
                props.setProperty("user", user);
                props.setProperty("password", pass);
                        conn = DriverManager.getConnection ("jdbc:postgresql://" + dbname, props);
                        conn.setAutoCommit(false);
                        conn.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);




_________________________________________

Pieter Zieschang

Modis IT Outsourcing GmbH
Kohlgartenstrasse 11, 04315-Leipzig

Amtsgericht Düsseldorf: HRB 78227
Geschäftsführer: Martin Wimmer, Andreas Buchelt

www.modis.de





From:        Dave Cramer <pg@fastcrypt.com>
To:        Pieter Zieschang <pieter.zieschang@modis.de>
Date:        29.06.2018 16:37
Subject:        Re: insert function runs forever if connection is lost, keeping the table locked
Sent by:        davecramer@gmail.com

---

On 29 June 2018 at 10:27, Pieter Zieschang <pieter.zieschang@modis.de> wrote:
Hi,

Thanks for your answer, unfortunately it didn't solve the problem.



I tried setting CallableStatement.setQueryTimeout(6).
This works, but causes the 2nd software run to die, because the deceased first run did never release the lock.
Die dead application however keeps the lock waiting.


Is there any chance that you have a connection pool in the middle ?




Dave Cramer

davec@postgresintl.com
www.postgresintl.com


From:        Dave Cramer <pg@fastcrypt.com>
To:        Pieter Zieschang <pieter.zieschang@modis.de>
Date:        29.06.2018 14:58
Subject:        Re: insert function runs forever if connection is lost, keeping the table locked
Sent by:        davecramer@gmail.com

---

On 28 June 2018 at 09:27, Pieter Zieschang <pieter.zieschang@modis.de> wrote:
Hi,

running pg-jdbc 42.2.2.jre7 against

PostgreSQL 10.4 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28), 64-bit

and using CallableStatement interface.
When the application crashes after cstmt.execute(), not closing or rolling back  anything the query stays active and keeps the table locked (the function, uses in/out parameters and inserts to a table).
This would probably be the same if the client suddenly disconnects with a open CallableStatement which was executed but not closed, committed or rolled back.

The application in question is required to use CallableStatement.

I tried with settings

tcp_keepalives_idle tcp_keepalives_interval tcp_keepalives_count

all set to 2.


Doesn't help, the query is still listed as active and the table lock is preventing other connections from doing anything for hours.


Is there any solution to this kind of deadlock caused by connection being lost?
What i would expect to happen: The DB recognises the connection is gone within 6 seconds and rolls back the transaction, thereby releasing the lock.

That is exactly what I would expect to happen as well. 

JDBC has a statement timeout setting. Have you tried that ?

What logs do you have from the server ?


Dave Cramer

davec@postgresintl.com
www.postgresintl.com


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