c3p0資料庫連線池死鎖解決
阿新 • • 發佈：2019-01-02
專案進行壓力測試的時候，執行大概1小時候，後臺丟擲以下異常：
Java程式碼
- Nov 9, 2012 1:41:59 AM com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
- WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@4b9cafa7 -- APPARENT DEADLOCK!!! Complete Status:
- Managed Threads: 3
-
Active Threads: 3
- Active Tasks:
- com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@19f67d43 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
-
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@599c706 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
- com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@32d95dc9 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
- Pending Tasks:
- com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@5c9c5133
-
com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask@1a971ac5
- com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@365e8926
- com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@787e39ac
- Pool thread stack traces:
- Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
- java.lang.StringCoding.set(StringCoding.java:53)
- java.lang.StringCoding.encode(StringCoding.java:270)
- java.lang.String.getBytes(String.java:946)
- com.mysql.jdbc.ConnectionImpl.configureCharsetProperties(ConnectionImpl.java:1578)
- com.mysql.jdbc.ConnectionImpl.configureClientCharacterSet(ConnectionImpl.java:1628)
- com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3425)
- com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2045)
- com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)
- com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
- sun.reflect.GeneratedConstructorAccessor35.newInstance(Unknown Source)
- sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
- java.lang.reflect.Constructor.newInstance(Constructor.java:513)
- com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
- com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
- com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
- com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)
- com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
- com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
- com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
- com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
- com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
- com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
- com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
- Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]
- com.mysql.jdbc.ResultSetImpl.getInstance(ResultSetImpl.java:344)
- com.mysql.jdbc.MysqlIO.buildResultSetWithUpdates(MysqlIO.java:2607)
- com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:2490)
- com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:1746)
- com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2135)
- com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2536)
- com.mysql.jdbc.ConnectionImpl.setupServerForTruncationChecks(ConnectionImpl.java:5240)
- com.mysql.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:3508)
- com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2045)
- com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:718)
- com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
- sun.reflect.GeneratedConstructorAccessor35.newInstance(Unknown Source)
- sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
- java.lang.reflect.Constructor.newInstance(Constructor.java:513)
- com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
- com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:302)
- com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:282)
- com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:135)
- com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
- com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
- com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
- com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
- com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
- com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
- com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
- Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]
- com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:562)
目測該問題是c3p0連線池導致的執行緒死鎖。
這種資料庫連線池執行緒死鎖的問題發生的原因可能有很多，我將我的配置環境以及解決方法貼出來供大家參考一下：
使用環境，spring + hibernate +c3p0
配置如下：<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
Java程式碼
- destroy-method="close">
- <property name="driverClass" value="com.mysql.jdbc.Driver"/>
- <property name="jdbcUrl" value="${db.url}?useUnicode=true&characterEncoding=UTF-8"/>
- <property name="user" value="${db.usrname}"/>
- <property name="password" value="${db.password}"/>
- <!--連線池中保留的最小連線數。-->
- <property name="minPoolSize" value="5"/>
- <!--連線池中保留的最大連線數。Default: 15 -->
- <property name="maxPoolSize" value="500"/>
- <!--初始化時獲取的連線數，取值應在minPoolSize與maxPoolSize之間。Default: 3 -->
- <property name="initialPoolSize" value="10"/>
- <!--最大空閒時間,60秒內未使用則連線被丟棄。若為0則永不丟棄。Default: 0 -->
- <property name="maxIdleTime" value="60"/>
- <!--當連線池中的連線耗盡的時候c3p0一次同時獲取的連線數。Default: 3 -->
- <property name="acquireIncrement" value="5"/>
- <!--JDBC的標準引數，用以控制資料來源內載入的PreparedStatements數量。但由於預快取的statements
- 屬於單個connection而不是整個連線池。所以設定這個引數需要考慮到多方面的因素。
- 如果maxStatements與maxStatementsPerConnection均為0，則快取被關閉。Default: 0-->
- <property name="maxStatements" value="0"/>
- <!--每60秒檢查所有連線池中的空閒連線。Default: 0 -->
- <property name="idleConnectionTestPeriod" value="60"/>
- <!--定義在從資料庫獲取新連線失敗後重復嘗試的次數。Default: 30 -->
- <property name="acquireRetryAttempts" value="30"/>
- <!--獲取連線失敗將會引起所有等待連線池來獲取連線的執行緒丟擲異常。但是資料來源仍有效
- 保留，並在下次呼叫getConnection()的時候繼續嘗試獲取連線。如果設為true，那麼在嘗試
- 獲取連線失敗後該資料來源將申明已斷開並永久關閉。Default: false-->
- <property name="breakAfterAcquireFailure" value="false"/>
- <!--因效能消耗大請只在需要的時候使用它。如果設為true那麼在每個connection提交的
- 時候都將校驗其有效性。建議使用idleConnectionTestPeriod或automaticTestTable
- 等方法來提升連線測試的效能。Default: false -->
- <property name="testConnectionOnCheckout" value="false"/>
- </bean>
這個配置中有一些屬性可能和死鎖有關：maxStatements 和checkoutTimeout(我沒有使用該屬性)
有人說c3p0本身沒有問題，導致問題是spring的原因，c3p0作為hibernate官方推薦的連線池，在效能和穩定性上都是中規中矩的。根據以前的使用經驗，我判斷也不是c3p0的問題。
Java程式碼
- <!--JDBC的標準引數，用以控制資料來源內載入的PreparedStatements數量。但由於預快取的statements
- 屬於單個connection而不是整個連線池。所以設定這個引數需要考慮到多方面的因素。
- 如果maxStatements與maxStatementsPerConnection均為0，則快取被關閉。Default: 0-->
- <property name="maxStatements" value="0"/>
- <!--連線池用完時客戶呼叫getConnection()後等待獲取連線的時間，單位：毫秒。超時後會丟擲-->
- <!--SQLEXCEPTION，如果設定0，則無限等待。Default:0-->
- <property name="checkoutTimeout" value="100"/>
修改後，問題沒有重現。