mysql连接池maxPoolSize设置1，却能打开3个连接

mysql连接池maxPoolSize设置1，却能打开3个连接。 为什么能多打开3个连接呢？比设置maxPoolSize的数量大？

连接DataSource基本信息打印：

{

    plat=com.mchange.v2.c3p0.ComboPooledDataSource[

        acquireIncrement->3,

        acquireRetryAttempts->30,

        acquireRetryDelay->1000,

        autoCommitOnClose->false,

        automaticTestTable->C3P0Test,

        breakAfterAcquireFailure->false,

        checkoutTimeout->20000,

        connectionCustomizerClassName->null,

        connectionTesterClassName->com.mchange.v2.c3p0.impl.DefaultConnectionTester,

        dataSourceName->1hge1689h1ps2bsx1kgrhzg|305eac01,

        debugUnreturnedConnectionStackTraces->false,

        description->null,

        driverClass->com.mysql.jdbc.Driver,

        factoryClassLocation->null,

        forceIgnoreUnresolvedTransactions->false,

        identityToken->1hge1689h1ps2bsx1kgrhzg|305eac01,

        idleConnectionTestPeriod->21600,

        initialPoolSize->3,

        jdbcUrl->jdbc: mysql: //192.168.1.130: 3306/doeis?useUnicode=true&characterEncoding=UTF-8,

        maxAdministrativeTaskTime->0,

        maxConnectionAge->0,

        maxIdleTime->25200,

        maxIdleTimeExcessConnections->0,

        maxPoolSize->1,

        maxStatements->0,

        maxStatementsPerConnection->0,

        minPoolSize->1,

        numHelperThreads->3,

        numThreadsAwaitingCheckoutDefaultUser->0,

        preferredTestQuery->null,

        properties->{

            user=******,

            password=******

        },

        propertyCycle->0,

        testConnectionOnCheckin->true,

        testConnectionOnCheckout->false,

        unreturnedConnectionTimeout->0,

        usesTraditionalReflectiveProxies->false

    ]

}

发现参数initialPoolSize设置的3，比maxPoolSize大。