I have several applications running on tomcat with a local PostgresSQL database. And tomcat occasionally reports the following errors:
org.postgresql.util.PSQLException: Connection attempt timed out.
I am able to connect to the database using other tools such as DBeaver. And this problem looks only happens when several applications are connecting to the database. So I want to know how to troubleshoot this issue. Is there any log in PostgresSQL that I can check?
PostgreSQL does have logging. It is very configurable, and we can't tell you how you have it configured. Common locations are /var/log/postgresql/, and in PGDATA/log/. However, a connection timeout will probably not be in the postgresql log as it probably never achieved contact with the postgresql server to start with.
Related
I am trying to connect one of my databases via DBeaver. It sometimes gets connected and sometimes does not. It says connection request timed out. I have tried increasing the timeout but it is of no help. I am able to connect other databases via DBeaver without any issues. When I try to connect this problematic DB via PgAdmin, it gets connected but takes a lot of time to connect as compared to other databases which get connected pretty soon. I am unable to figure out where exactly the problem could be.
We have an application on IBM WebSphere Application Server 7.x and it connects to a remote database on z/os DB2 10.x. For annual operation, DB2 shut down and restarted. After starting the database, we first get
com.ibm.websphere.ce.cm.StaleConnectionException
and then we get
The database manager is not able to accept new requests, has terminated all requests in progress, or has terminated this particular request due to unexpected error conditions detected at the target system. ERRORCODE=-4499, SQLSTATE=58009
The connection between WebSphere and DB2 tested by 'test Connection' in WAS datasource. Both systems are up and running but there is no correct connection between them! There was no change in DB2, WAS, and JDBC driver.
Update: The JDBC driver version is 4.15.134, connection properties is IBM WebSphere default setting and the connection is direct to DB2. Another problem later showed that while the connection still has the problem, executing the query directly on z/OS's DB2 gets the same the error. The query consist of a select with a join on two different tables, selecting on each table is ok, but the final query does not work and gets ERRORCODE=-4499, SQLSTATE=58009.
Update 2
The detail of environment is: IBM WebSphere Application Server 7.0.0.45, DB2 10.1, Java version 1.6 SR16 and z/OS 1.13.
This specific query gets the error in all environments, on all application server, z/os SPUFI, database viewer, such as DBeaver.
Any help is greatly appreciated.
Finally, we found the solution, ran REORG and RUNSTATS on both tables and on all their partitions, and the error vanished both on the application and SPUFI. I guess something went wrong during restart and tables corrupted. Now everything is ok.
If I got you correctly, you complain on inability of the driver to reestablish the database connections after the DB2 for Z/OS restart.
If yes, then have you tried to set the corresponding connection properties described at the following link?
Configuration of Sysplex workload balancing and automatic client reroute for Java clients
I am new to freenode and postgresql. I am trying to migrate from mysql to postgresql. Currently trying to set up server for ssl. Have created my server certs and configured the .conf files for ssl according to the manual as far as I can see. Trying to restart postgre sql service fails. Windows event log gives me an event ID of 0 and says
pg_ctrl could not start server examine the log output.
I can't find any log detailing the failure to start in the postgresql folders.
I have tried to register the pgevent.dll as advised by the postgresql manual (18.11 of most recent version), but I get an error message
The module "C:postgreSQL\pg10\lib\postgresql\pgevent.dll" was loaded but the entry-point DllRegisterServer was not found
I believe that means it is either not a registrable dll or it's corrupt.
Can anyone please advise how I can track on Windows the error that is causing Postgre to fail to start?
We are using PostgreSQL Crane plan, and got a lot of log like this
app postgres - - [5-1] ... LOG: could not receive data from client: Connection reset by peer
We are using about 50 dynos.
Is PostgreSQL running out of connections with bunch of dynos?
Can someone help me explain this case?
Thanks
From what I've found the cause for the errors is the client not disconnecting at the end of the session, or a new connection not being created.
New connection solving the problem:
Postgres error on Heroku with Resque
Explicit disconnection solving the problem:
https://github.com/resque/resque/issues/367 (comment #2)
There's a Heroku FAQ entry on this: Understanding Heroku Postgres Log Statements and Common Errors: could not receive data from client: Connection reset by peer.
Although this log is emitted from postgres, the cause for the error has nothing to do with the database itself. Your application happened to crash while connected to postgres, and did not clean up its connection to the database. Postgres noticed that the client (your application) disappeared without ending the connection properly, and logged a message saying so.
If you are not seeing your application’s backtrace, you may need to ensure that you are, in fact, logging to stdout (instead of a file) and that you have stdout sync’d.
I have a Tomcat and PostgreSQL installed on a server. I'm having a connection problem trying to connect from my servlet to PostgreSQL database using c3p0 pool.
I can reach DB if I'm running Tomcat locally on my laptop. Also I can connect from server to DB using psql (i.e. command line sql utility). But when I'm trying to deploy my servlet to server and establish a connection I'm getting the following error:
java.sql.SQLException: Connections could not be acquired from the underlying database!
com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
...
com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
What should I check to locate a problem? It should be a trivial issue but may be due to 4 a.m. I'm missing something :) Thanks in advance!
PS: Connection from all network interfaces are allowed to database. PostgreSQL JDBC driver and c3p0 pool are distributed in WAR. Tomcat configuration is very default. JNDI is not used.
You need to check a few things:
java.policy which tomcat is using
(e.g.
/etc/tomcat5.5/policy.d/02debian.policy)
db server settings (e.g.
/etc/postgresql/pg_hba.conf)
try connecting without pool first as
in my case c3p0 was hiding important information from me
Adding to #Alexey's answer, I had this issue with Tomcat and PostgreSQL 9.4. In my case, the md5 authentication method in postgres was causing the issue.
If you are using Windows server or RHEL server, make sure you update the authentication method in pg_hba.conf file. Modify it to trust and restart postgresql.