is c3p0 connection pool thread safe or not..? - c3p0

Question

hai this chandrashekhar,
when I post the multiple requests(100) at a time it creates c3p0 Instances.
Ex::
[AbstractPoolBackedDataSource] Initializing c3p0 pool...
com.mchange.v2.c3p0.PoolBackedDataSource#3b9421d5 [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource#8f5cd4d1 [ acquireIncrement -> 5, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> true, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> true, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hge2v08pob8zy1nl2rit|1474b36, idleConnectionTestPeriod -> 3600, initialPoolSize -> 10, maxAdministrativeTaskTime -> 600, maxConnectionAge -> 0, maxIdleTime -> 18000, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 50, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 10, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource#3a7ecbf6 [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|87f988, jdbcUrl -> jdbc:mysql://localhost:3306/tiscover, properties -> {user=******, password=******} ], preferredTestQuery -> null, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 600, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|6c2668, numHelperThreads -> 10 ]
13:24:16,003 INFO [AbstractPoolBackedDataSource]
Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource#38d1c65b [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource#efa9b134 [ acquireIncrement -> 5, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> true, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> true, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hge2v08pob8zy1nl2rit|d46725, idleConnectionTestPeriod -> 3600, initialPoolSize -> 10, maxAdministrativeTaskTime -> 600, maxConnectionAge -> 0, maxIdleTime -> 18000, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 50, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 10, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource#f3230993 [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|b31fb1, jdbcUrl -> jdbc:mysql://localhost:3306/tiscover, properties -> {user=******, password=******} ], preferredTestQuery -> null, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 600, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|9861d7, numHelperThreads -> 10 ]
13:24:16,004 INFO [AbstractPoolBackedDataSource]
Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource#3b6dc297 [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource#433920d4 [ acquireIncrement -> 5, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> true, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> true, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hge2v08pob8zy1nl2rit|3561b9, idleConnectionTestPeriod -> 3600, initialPoolSize -> 10, maxAdministrativeTaskTime -> 600, maxConnectionAge -> 0, maxIdleTime -> 18000, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 50, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 10, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource#4084843c [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|3f9de3, jdbcUrl -> jdbc:mysql://localhost:3306/tiscover, properties -> {user=******, password=******} ], preferredTestQuery -> null, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 600, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|6dfb07, numHelperThreads -> 10 ]
13:24:16,004 INFO [AbstractPoolBackedDataSource]
Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource#3bcf7210 [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource#896b85d4 [ acquireIncrement -> 5, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> true, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, debugUnreturnedConnectionStackTraces -> true, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hge2v08pob8zy1nl2rit|16e47cb, idleConnectionTestPeriod -> 3600, initialPoolSize -> 10, maxAdministrativeTaskTime -> 600, maxConnectionAge -> 0, maxIdleTime -> 18000, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 50, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 10, nestedDataSource -> com.mchange.v2.c3p0.DriverManagerDataSource#f06dd726 [ description -> null, driverClass -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|bd7db5, jdbcUrl -> jdbc:mysql://localhost:3306/tiscover, properties -> {user=******, password=******} ], preferredTestQuery -> null, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 600, usesTraditionalReflectiveProxies -> false; userOverrides: {} ], dataSourceName -> null, factoryClassLocation -> null, identityToken -> 1hge2v08pob8zy1nl2rit|1e616dc, numHelperThreads -> 10 ]
13:24:16,006 INFO [AbstractPoolBackedDataSource]
....etc 100 times.
what is the meaning behind this, is 100 connection pool Instances created..?
is c3p0 connection pool is not thread safe..? if so how we are geoing to handle..?
pls any one help me.
thanks in advance,
ChandraShekhar

Answer 1

Firstly, a connection can only run on interaction with the database at a time. If you share a connection across multiple threads, the behaviour would be random. Ideally, you would just get a connection from the pool when you want to interact with DB like run some INSERT/UPDATE/DELETE statements and get the update counts or run SELECT statements and read the result sets and then you close all the resources (viz. ResultSets, Statements and Connection).
If the connection comes from a connection pooler, then the close() call on such a connection is handled by the pooler to return the connection back to pool.
The statements you printed are INFOs from the pooler about the connection pool created.