A checked-out resource is overdue, and will be destroyed: com.mchange.v2.c3p0.impl.NewPooledConnection@437c5a2d issue tomcat 7 c3p0

Question

we use tomcat 7 and c3p0 as a connection pool.But since starting tomcat every 3 seconds i see many warnings: 17-Jan-2023 20:35:49.259 INFO [C3P0PooledConnectionPoolManager[identityToken->z8kfltat1hfo3gq19fe7ui|2e3d1388]-AdminTaskTimer] com.mchange.v2.resourcepool.BasicResourcePool. A checked-out resource is overdue, and will be destroyed: com.mchange.v2.c3p0.impl.NewPooledConnection@7abb733e

Here is the connection pool config: 17-Jan-2023 20:39:4.647 INFO [http-nio-8080-exec-2] com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource. Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 20, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> z8kfltat1hftvt811qptc9|2e3d1388, debugUnreturnedConnectionStackTraces -> false, description -> OLTP Connection, driverClass -> oracle.jdbc.driver.OracleDriver, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> z8kfltat1hftvt811qptc9|2e3d1388, idleConnectionTestPeriod -> 300, initialPoolSize -> 3, jdbcUrl -> jdbc:oracle:thin:@192.168.0.xx:xxxx:xxxx, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 3 0, maxIdleTimeExcessConnections -> 30, maxPoolSize -> 500, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 50, numHelperThreads -> 3, preferredTestQuery -> SELECT 1 FROM dual, privilegeSpawnedThreads -> false, properties -> {user= , password= }, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> true, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 12, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]

PS sorry for my english:)

I've already read every single issue posted here,tried some,but no clue.We call connection.close() in finally for each connection.

Answer 1

You have unreturnedConnectionTimeout set to 12 seconds. The message you are seeing is due to Connection s not being promptly returned to the pool, triggering destruction of those Connection s.

Despite your protestation that you call Connection.close() in a finally block, either your uses of Connection s are taking longer than you expect (your database operations take more than 12 seconds), or you are leaking Connection s.

c3p0 has a facility to debug apparently leaked Connection s. Set debugUnreturnedConnectionStackTraces to true (only to debug, it has a performance cost), and you will see the stack traces that checked out the Connection s that c3p0 times out and destroys.

If your database operations just sometimes take more than 12 seconds, just set unreturnedConnectionTimeout to a larger value. If you find that there's a leak, you'll see where it is to fix it.

See the docs, here .