We are using ADO to access Oracle 10g release 2, Oledb provider for Oracle 10g. We are facing some issue with the connection pooling. The database reside on the remote machine and connection pooling is occuring as it should. But if the remote machine goes down for some reason, the connection is returned from the pool and query on that connection fails. When this connection is closed, it is returned back to the pool instead of being invalid. The subsequent connection opening requests are sucessfull but query fails. This is strange behaviour, according to OLEDB specifications, provider must support DBPROP_CONNECTIONSTATUS property, thus in case of invalid connection, it would not be returned back to the pool.
Things get weired when the remote machine comes up. The connections in the pool are still invalid and although the connection opening succeeds, query on the connection fails. Oracle OLEDB is unable to connect to the server anymore and we have to restart our application. Well this is undesired cause our application is a critical application.
Any ideas on how to get over this.
Thanks
Mubashir
If you are doing this programmatically, use a try block, so that if something does happen, it won't fail. With a try block, you can catch an exception and ignore it, so that the errors are shushed.
You could tell the pool to not accept invalid connections, by marking the connection invalid before it is returned to the pool.
Connections are recovered after 10 minutes by default. Time can be set by the registry key SPTimeout under the oledb provider's root key.
Actually the default connection pool timeout is 120 seconds at least for this Oracle 11 32-bit OLEDB installation. You can find the registry settings at:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Oracle\KEY_orac
Where KEY_orac is the KEY_<oracle_home_name>
The key name is ORAMTS_CONN_POOL_TIMEOUT and the default value is 120.
It does not appear that you can set connection pool parameters at the connection string level.
In most connection pool implementation it is possible to check the connection before using it. For example: you define a check query like select * from dual and if you pick up a connection from the pool this query will be executed. If it fails, then the connection will be excluded from the pool and a new one will be opened.
Related
I have an Oracle DB RAC setup of 2 servers and config SCAN hostname pointing to both servers. My Websphere application server config with jdbc string like below and connection pool of 50:
jdbc:oracle:thin:#//scan-hostname:port/dbname
Everything works fine and both db servers are getting request as expected, except that when either node is down (and the other node is normal), my application will get all kinds of exceptions like (connection reset/JDBC commit failed/Connection is closed) just within first several minutes and normal afterwards.
My guess is those pooled connections to the failing node does not do any retry or failover and just throw exceptions. Is it expected behavior for oracle RAC, that failover only working for new connections not existing connections, or am I missing something somewhere to enable failover?
When our application tries to connect Oracle database, this exception is thrown:
java.sql.SQLRecoverableException: Connection has been administratively disabled by console/admin command. Try later. java.lang.Exception: It was disabled at Tue Oct 20 23:55:14 CEST 2015
But, from Weblogic console the connection test returns OK.
Weblogic version: 12.1.3.0.0
Any explanation is welcome. Thanks
The reason the test works is because that is creating a connection and running a test query. That is not what your code is doing when it is using the data source in an ejb. The code is going through the connection pool and that is what has been marked as bad. There is no solution provided by Oracle that I have found except to: restart the server and that will re-enable the connection pool.
I suspect you have "Test connections on reserve" set because that is when this usually arises. What Weblogic does is: before it returns a connection from the pool it will run a test query, if the test query fails it waits and runs it one more time. If the query fails again it marks the connection as unhealthy. If all the connections in the pool become unhealthy it will mark the pool as disabled and gives you the error message you see: 'Connection has been administratively disabled by console/admin command. Try later.'
In regards to the 'Try Later' part of the error message, as far as I can tell Oracle is wrong about trying again later. I have never seen it recover later.
I'd like to share this article that help me out to understand better my problem:
https://www.techpaste.com/2012/09/connection-administratively-destroyed-reconnect-oracle-weblogic-server/
The “java.sql.SQLException: Connection has been administratively destroyed.” is expected:
the DB was shutdown; even if it was restarted later, the JDBC connection are pointing to DB processes
that have been destroyed.
You need to restart your WebLogic Server to recreate new JDBC connections.
All the current transactions are lost, as the database was shutdown.
High availability of your RDBMS is required to minimize this issue.
Is there any other error before that one ?
Maybe in the log you can find that connection is been closed.
You can avoid this by selecting "Test on Connection Reserve" in the datasource.
Does SQL Azure allow 3-rd party connection pool like HikariCP or BoneCP?
We configured HikariCP it works when we just run app but later db doesnt response on request. Is it HikariCP issue or it's common connection poool issue and no need spending more time on investigation?
HikariConfig config = new HikariConfig();
config.setMaximumPoolSize(50);
config.setDriverClassName(env.getProperty("jdbc.driverClassName"));
config.setJdbcUrl(env.getProperty("jdbc.url"));
config.setUsername(env.getProperty("jdbc.user"));
config.setPassword(env.getProperty("jdbc.pass"));
config.addDataSourceProperty("cachePrepStmts", env.getProperty("jdbc.cachePrepStmts"));
config.addDataSourceProperty("prepStmtCacheSize", env.getProperty("jdbc.prepStmtCacheSize"));
config.addDataSourceProperty("prepStmtCacheSqlLimit", env.getProperty("jdbc.prepStmtCacheSqlLimit"));
config.addDataSourceProperty("useServerPrepStmts", env.getProperty("jdbc.useServerPrepStmts"));
See this SQL Azure page re: Connection Constraints.
Maximum allowable durations are subject to change depending on the resource usage.
A logged-in session that has been idle for 30 minutes will be terminated
automatically. We strongly recommend that you use the connection pooling and
always close the connection when you are finished using it so that the unused
connection will be returned to the pool. For more information about connection
pooling, see Connection Pooling.
See if any of these errors match up to your logs. Search that page for "terminated" and "busy" to find error codes that might be relevant to your issue.
I would suggest setting the maxLifetime property in HikariCP to 15 minutes, and the idleTimeout to 2 minutes.
There is nothing on the SQL Azure side that would prohibit you from using a 3rd party connection pool. My guess is that the connection failed between the server and the client and the client didn't remove the connection from the pool.
Moving forward, I'd ensure that whichever 3-rd part connection pool you end up using tests that the connection exists before taking it out of the pool for use.
Hope that helps.
We are using tomcat jdbc connection pooling with Oracle database.
Recently, we encountered problem that there are too many inactive session in Oracle database from JDBC THIN CLIENT.
Can anyone help us in this? Why is it causing inactive session in the database and what can be the solution to this.
Thank you.
Adjust settings of your pool, following the documentation. Setting maxIdle and minEvictableIdleTimeMillis to low values would ensure that idle connections are evicted fast, and that few idle connections stay open. Obviously, it will also make your pool less efficient, since connections will be closed and opened more frequently.
If you are getting SQLExceptions because connections have timed out, you should set a validationQuery (to something like SELECT 0 FROM DUAL) and your connections will be tested before they are checked-out of the pool. Any connection that has failed will be replaced by a working connection and then returned to your code.
When the Oracle 10 databases are up and running fine, OCILogon2() will connect immediately. When the databases are turned off or inaccessible due to network issues - it will fail immediately.
However when our DBAs go into emergency maintenance and block incomming connections, it can take 5 to 10 minutes to timeout.
This is problematic for me since I've found that OCILogin2 isn't thread safe and we can only use it serially - and I connect to quite a few Oracle DBs. 3 blocked servers X 5-10 minutes = 15 to 30 minutes of lockup time
Does anyone know how to set the OCILogon2 connection timeout?
Thanks.
I'm currenty playing with OCI and it seems to me that it's impossible.
The only way I can think of is to use non-blocking mode. You'll need OCIServerAttach() and OCISessionBegin() instead of OCILogon() in this case. But when I tried this, OCISessionBegin() constantly returns OCI_ERROR with the following error code:
ORA-03123 operation would block
Cause: The attempted operation cannot complete now.
Action: Retry the operation later.
It looks strange and I don't yet know how to deal with it.
Possible workaround is to run your logon in another process, which you can kill after timeout...
We think we found the right file setting - but it's one of those problems where we have to wait until something rare and horrible occurs before we can verify it :-/
[sqlnet.ora]
SQLNET.OUTBOUND_CONNECT_TIMEOUT=60
From the Oracle docs..
http://download.oracle.com/docs/cd/B28359_01/network.111/b28317/sqlnet.htm#BIIFGFHI
5.2.35 SQLNET.OUTBOUND_ CONNECT _TIMEOUT
Purpose
Use the SQLNET.OUTBOUND_ CONNECT _TIMEOUT parameter to specify the time, in seconds, for a client to establish an Oracle Net connection to the database instance.
If an Oracle Net connection is not established in the time specified, the connect attempt is terminated. The client receives an ORA-12170: TNS:Connect timeout occurred error.
The outbound connect timeout interval is a superset of the TCP connect timeout interval, which specifies a limit on the time taken to establish a TCP connection. Additionally, the outbound connect timeout interval includes the time taken to be connected to an Oracle instance providing the requested service.
Without this parameter, a client connection request to the database server may block for the default TCP connect timeout duration (approximately 8 minutes on Linux) when the database server host system is unreachable.
The outbound connect timeout interval is only applicable for TCP, TCP with SSL, and IPC transport connections.
Default
None
Example
SQLNET.OUTBOUND_ CONNECT _TIMEOUT=10