[DBCP-342] Not cleaned up commons pool's evictor task when SQLException occurs after the GenericObjectPool is initialized in createDataSource.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.3, 1.4
• Fix Version/s: 1.3.1, 1.4.1

Environment

• commons-pool : 1.4
• commons-dbcp : 1.4, 1.3 both
• dbms : MSSQL 2007

• Assignee: Unassigned
• Reporter: byungchol.kim
• Created: 03/Sep/10 08:48
• Updated: 13/May/19 12:27
• Resolved: 25/Feb/15 00:21

Description

JIRA DBCP-93 bts is not fixed correctly
(JIRA DBCP-93 : If SQLException occurs after the GenericObjectPool is initialized in createDataSource, the evictor task is not cleaned up)

Only one evictor timer thread leaves but evictor timer task queued as many as createDataSource() method called.
queued evictor will keep tries to make connection to meet min idle connection.
if suddenly dbms become stable and can accept connection again,
then every queued evictor will try to make connection simultaneously.

In my case there were more then 100000 user requests while I set wrong password to database,
when I change my password to correct in database
more then 100000 evictor tries to make connection
and finally mssql makes connections as many as integer limit and dbms dies.

here is my test.

TestBasicDataSource.java

    public void testCreateDataSourceCleanupEvictor() throws Exception {
    	ds.close();
    	ds = null;
    	ds = createDataSource();
    	ds.setDriverClassName("org.apache.commons.dbcp.TesterConnRequestCountDriver");
    	ds.setUrl("jdbc:apache:commons:testerConnRequestCountDriver");
    	ds.setValidationQuery("SELECT DUMMY FROM DUAL");
    	ds.setUsername("username");
    	
    	// Make password incorrect, so createDataSource will throw
    	ds.setPassword("wrong");
    	// Set timeBetweenEvictionRuns > 0, so evictor will be created
    	ds.setTimeBetweenEvictionRunsMillis(100);
    	// Set min idle > 0, so evictor will try to make connection as many as idle count
    	ds.setMinIdle(2);
    	
    	Class.forName("org.apache.commons.dbcp.TesterConnRequestCountDriver");
    	TesterConnRequestCountDriver testerDriver = (TesterConnRequestCountDriver) DriverManager.getDriver("jdbc:apache:commons:testerConnRequestCountDriver");
    	testerDriver.initConnRequestCount();
    	
    	// user request 10 times
    	for (int i=0; i<10; i++) {
    		try {
    			@SuppressWarnings("unused")
				DataSource ds2 = ds.createDataSource();
    		} catch (SQLException e) {
    			// Ignore
    		}
    	}

    	// sleep 1000ms. evictory will invoked 10 times.
    	Thread.sleep(1000);
    	
    	// if orphan evictor is alive, connection request count will be 100 which is denoted from (ds.createDataSource() count * evictor invoke count)
    	// if DBMS connection is back to stable in 10 minutes then this test case will make 120000 connections simultaneously
    	// 		120000 connections = ds.createDataSource() count (10) * evictor invoke count (6000) * min idle (2)
    	// but if evictor is cleaned up, connection request count will be only 10 (ds.createDataSource() count )
    	assertEquals(10, testerDriver.getConnectionRequestCount());
    	
    	// fail to create datasource then clean up orphan connection pool and evictor in connnection pool
    	assertNull(ds.connectionPool);
    }
}

Issue Links

• blocks: DBCP-353 When DB Restarts(Bounce) the number ESTABLISHED DB connections exceeds its maximum configured limit.
• is duplicated by: DBCP-339 orphaned connectionPools created on Exception within createDataSource method
• is duplicated by: DBCP-379 number of connections created has crossed more than maxActive