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  • c3p0数据库连接池死锁问题

    项目进行压力测试的时候，运行大概1小时候，后台抛出以下异常：

    Java代码  收藏代码
    1. Nov 9, 2012 1:41:59 AM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run  
    2. WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@4b9cafa7 -- APPARENT DEADLOCK!!! Complete Status:   
    3.         Managed Threads: 3  
    4.         Active Threads: 3  
    5.         Active Tasks:   
    6.                 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@19f67d43 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)  
    7.                 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@599c706 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)  
    8.                 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@32d95dc9 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)  
    9.         Pending Tasks:   
    10.                 com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@5c9c5133  
    11.                 com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@1a971ac5  
    12.                 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@365e8926  
    13.                 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@787e39ac  
    14. Pool thread stack traces:  
    15.         Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]  
    16.                 java.lang.StringCoding.set(StringCoding.java:53)  
    17.                 java.lang.StringCoding.encode(StringCoding.java:270)  
    18.                 java.lang.String.getBytes(String.java:946)  
    19.                 com.mysql.jdbc.ConnectionImpl.configureCharsetProperties(ConnectionImpl.java:1578)  
    20.                 com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1628)  
    21.                 com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3425)  
    22.                 com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2045)  
    23.                 com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)  
    24.                 com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)  
    25.                 sun.reflect.GeneratedConstructorAccessor35.newInstance(Unknown Source)  
    26.                 sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)  
    27.                 java.lang.reflect.Constructor.newInstance(Constructor.java:513)  
    28.                 com.mysql.jdbc.Util.handleNewInstance(Util.java:406)  
    29.                 com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)  
    30.                 com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)  
    31.                 com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)  
    32.                 com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)  
    33.                 com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)  
    34.                 com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)  
    35.                 com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)  
    36.                 com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)  
    37.                 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)  
    38.                 com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)  
    39.         Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]  
    40.                 com.mysql.jdbc.ResultSetImpl.getInstance(ResultSetImpl.java:344)  
    41.                 com.mysql.jdbc.MysqlIO.buildResultSetWithUpdates(MysqlIO.java:2607)  
    42.                 com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:2490)  
    43.                 com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:1746)  
    44.                 com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2135)  
    45.                 com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2536)  
    46.                 com.mysql.jdbc.ConnectionImpl.setupServerForTruncationChecks(ConnectionImpl.java:5240)  
    47.                 com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3508)  
    48.                 com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2045)  
    49.                 com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)  
    50.                 com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)  
    51.                 sun.reflect.GeneratedConstructorAccessor35.newInstance(Unknown Source)  
    52.                 sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)  
    53.                 java.lang.reflect.Constructor.newInstance(Constructor.java:513)  
    54.                 com.mysql.jdbc.Util.handleNewInstance(Util.java:406)  
    55.                 com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)  
    56.                 com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)  
    57.                 com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)  
    58.                 com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)  
    59.                 com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)  
    60.                 com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)  
    61.                 com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)  
    62.                 com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)  
    63.                 com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)  
    64.                 com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)  
    65.         Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]  
    66.                 com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:562)  

     目测该问题是c3p0连接池导致的线程死锁。

    这种数据库连接池线程死锁的问题发生的原因可能有很多，我将我的配置环境以及解决方法贴出来供大家参考一下：

    使用环境，spring + hibernate +c3p0

    配置如下：<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"

    Java代码  收藏代码
    1.     destroy-method="close">  
    2.   <property name="driverClass" value="com.mysql.jdbc.Driver"/>  
    3.   <property name="jdbcUrl" value="${db.url}?useUnicode=true&amp;characterEncoding=UTF-8"/>  
    4.           <property name="user" value="${db.usrname}"/>  
    5.           <property name="password" value="${db.password}"/>  
    6.   <!--连接池中保留的最小连接数。-->  
    7.   <property name="minPoolSize" value="5"/>  
    8.   <!--连接池中保留的最大连接数。Default: 15 -->  
    9.   <property name="maxPoolSize" value="500"/>  
    10.   <!--初始化时获取的连接数，取值应在minPoolSize与maxPoolSize之间。Default: 3 -->  
    11.   <property name="initialPoolSize" value="10"/>  
    12.   <!--最大空闲时间,60秒内未使用则连接被丢弃。若为0则永不丢弃。Default: 0 -->  
    13.   <property name="maxIdleTime" value="60"/>  
    14.   <!--当连接池中的连接耗尽的时候c3p0一次同时获取的连接数。Default: 3 -->  
    15.   <property name="acquireIncrement" value="5"/>  
    16.   <!--JDBC的标准参数，用以控制数据源内加载的PreparedStatements数量。但由于预缓存的statements  
    17.  属于单个connection而不是整个连接池。所以设置这个参数需要考虑到多方面的因素。  
    18.  如果maxStatements与maxStatementsPerConnection均为0，则缓存被关闭。Default: 0-->  
    19.   <property name="maxStatements" value="0"/>  
    20.   <!--每60秒检查所有连接池中的空闲连接。Default: 0 -->  
    21.   <property name="idleConnectionTestPeriod" value="60"/>  
    22.   <!--定义在从数据库获取新连接失败后重复尝试的次数。Default: 30 -->  
    23.   <property name="acquireRetryAttempts" value="30"/>  
    24.   <!--获取连接失败将会引起所有等待连接池来获取连接的线程抛出异常。但是数据源仍有效  
    25.  保留，并在下次调用getConnection()的时候继续尝试获取连接。如果设为true，那么在尝试  
    26.  获取连接失败后该数据源将申明已断开并永久关闭。Default: false-->  
    27.   <property name="breakAfterAcquireFailure" value="false"/>  
    28.   <!--因性能消耗大请只在需要的时候使用它。如果设为true那么在每个connection提交的  
    29. 时候都将校验其有效性。建议使用idleConnectionTestPeriod或automaticTestTable  
    30. 等方法来提升连接测试的性能。Default: false -->  
    31.   <property name="testConnectionOnCheckout" value="false"/>  
    32.     </bean>  

     这个配置中有一些属性可能和死锁有关：maxStatements 和checkoutTimeout(我没有使用该属性)

    有人说c3p0本身没有问题，导致问题是spring的原因，c3p0作为hibernate官方推荐的连接池，在性能和稳定性上都是中规中矩的。根据以前的使用经验，我判断也不是c3p0的问题。

    Java代码  收藏代码
    1. <!--JDBC的标准参数，用以控制数据源内加载的PreparedStatements数量。但由于预缓存的statements  
    2.        属于单个connection而不是整个连接池。所以设置这个参数需要考虑到多方面的因素。  
    3.        如果maxStatements与maxStatementsPerConnection均为0，则缓存被关闭。Default: 0-->  
    4.  <property name="maxStatements" value="0"/>  
    5. <!--连接池用完时客户调用getConnection()后等待获取连接的时间，单位：毫秒。超时后会抛出-->  
    6.  <!--SQLEXCEPTION，如果设置0，则无限等待。Default:0-->  
    7.  <property name="checkoutTimeout" value="100"/>  

      修改后，问题没有重现。

    来自：http://www.cnblogs.com/zhishan/archive/2012/11/09/2761980.html
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  • 原文地址：https://www.cnblogs.com/telwanggs/p/5832212.html
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