I`m in the development stage of an app and I don't make many server\cloud sql calls but for some reason I have an average of 400 usage hours a month.
When I look at the cloud sql active connections dashboard I see there is always at least one active connection but in the read\write operations it's usually on 0 besides the occasional small bumps.
I create a new connection each time I make a request to the server\cloud sql and close the connection each time when I return the response.
the connection code is(I followed the guestbook tutorial\example)
Class.forName("com.mysql.jdbc.GoogleDriver");
this.dbUrl = "jdbc:google:mysql://trivia9991:triviadb?user=root";
this.dbConn = DriverManager.getConnection(dbUrl);
the closing connection code is
this.dbConn.close();
How can this keep a connection open at all time?
If the connection close code is actually running this should not be the issue. You should make sure that the connection is closed even if an exception occurs before hand.
It is also possible that a connection you made using the MySQL command line client is still open.
You can examine what connections are open by connecting using the MySQL command line client and running a SHOW PROCESSLIST; statement.
Related
I use a DBLINK/Oracle Gateway to connect to an external non-oracle database. i have a timeout setting of 5 minutes.
when I connect using dblink, for the first time, it runs fine. After the idle time of 5 minutes, when I run the same sql again, it throws me the bellow error -
ORA-28511: lost RPC connection to heterogeneous remote agent using SID. ****
ORA-28509: unable to establish a connection to non-Oracle system
ORA-02063: preceding line from DB2T
Then when i run the sql again, its connecting fine. i guess its establishing a new connection.
Why am i getting the connection error and why oracle is not simply establishing a new connection when the previous connection is timed out?
Is there a way to not get the error and connect seamlessly or to suppress the error?
Easily replicable in sql developer by running a sql and waiting for 5 minutes.
Thanks in Advance.
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.
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.
I am working in an environment where we get production issues from time to time related to Oracle connections. We use ODP.NET from ASP.NET applications, and we suspect the firewall closes connections that have been in the connection pool too long.
Sometimes we get an "ORA-12571: TNS packet writer failure" error, and sometimes we get "ORA-03135: connection lost contact."
I was wondering if someone has run into this and/or has an understanding of the difference between the 2 errors.
Using a mobile phone analogy:
ORA-12571 (Failure) Means call is dropped.
ORA-03135 (Connection Lost) Other party hung up.
My understanding is that 3135 occurs when a connection is lost. This doesn't tell you why the connection was lost, though. It may have been terminated by the server because the server failed to recieve a response to a probe for a certain amount of time, and assumed that the connection was dead. Or (I'm not sure about this) the exact reverse of that: the client failed to recieve a probe response from the server for a certain amount of time, so it assumed the connection was lost. The "certain amount of time" is cotrolled by SQLNET.EXPIRE_TIME=[minutes] in sqlnet.ora.
As for 12571, my (again vague) understanding is that there was a sudden failure to send a packet during communication with the server, and that this is typically caused by some software or hardware interfering with the connection (either by design, or by error). For instance, if you pull out your ethernet cable and then try to execute a query, you'll probably get this. Or if a firewall or anti-malware application decides to block the traffic.
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