[
https://issues.apache.org/jira/browse/DBCP-328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Phil Steitz closed DBCP-328.
----------------------------
Resolution: Duplicate
Duplicates DBCP-300
> exponential wait when requesting connections while the database is down
> -----------------------------------------------------------------------
>
> Key: DBCP-328
> URL: https://issues.apache.org/jira/browse/DBCP-328
> Project: Commons Dbcp
> Issue Type: Bug
> Affects Versions: 1.2.2
> Environment: Tomcat Apache 5.5.28
> MySQL 5.1 / Connector/J 5.1.5
> JDK 1.5.0_22
> Reporter: Nick Brachet
>
> 2 problems in one but they are very related:
> # When the database is down (the actual server/machine, not the MySQL
> instance) the JDBC driver will wait {{connectTimeout}} before timing out.
> {{BasicDataSource.createDataSource()}}, which calls
> {{validateConnectionFactory()}} when it initializes, is synchronized. So each
> threads are waiting on the synchronize lock so they can all then wait
> {{connectTimeout}} before finally timing out.
> Imagine a 5sec {{connectTimeout}} and 10 concurrent theads, the last thread
> will timeout after roughly 50 seconds.
> # Similarly when the database dies (again the actual server/machine, not the
> instance), after {{BasicDataSource}} has initialized, the JDBC driver will
> again wait {{connectTimeout}} before timing out when new connections are
> created to grown the pool. {{PoolableConnectionFactory#makeObject()}}, which
> calls {{createConnection()}}, is also synchronized causing the same
> exponential wait for any threads requesting a connection from the pool.
> Maybe I should explain that Connector/J closes the actual connection when it
> detects a communication failure with the database, and the connection is then
> removed from the pool. So when the database server dies the pool gets
> depleted and new connections need to be created.
> I am not sure how to address #1 easily but #2 can be addressed by calling
> {{createConnection()}} outside of any locks.
> For example:
> {noformat}
> public Object makeObject() throws Exception {
> ConnectionFactory connFactory;
> KeyedObjectPoolFactory stmtPoolFactory;
> ObjectPool pool;
> synchronized (this) {
> connFactory = _connFactory;
> stmtPoolFactory = _stmtPoolFactory;
> pool = _pool;
> }
> Connection conn = connFactory.createConnection();
> if(null != stmtPoolFactory) {
> KeyedObjectPool stmtpool = stmtPoolFactory.createPool();
> conn = new PoolingConnection(conn,stmtpool);
> stmtpool.setFactory((PoolingConnection)conn);
> }
> return new PoolableConnection(conn,pool,_config);
> }
> {noformat}
> Although there may be some problem if the pool is swapped while creating a
> connection...
> See also dbcp-300.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
