淺析tomcat jdbc的ResetAbandonedTimer

序

當設置了remove-abandoned=true後，就開啓了鏈接池鏈接泄露的檢查。

定時任務

org.apache.tomcat.jdbc.pool#PoolCleaner

protected static class PoolCleaner extends TimerTask {
        protected WeakReference<ConnectionPool> pool;
        protected long sleepTime;

        PoolCleaner(ConnectionPool pool, long sleepTime) {
            this.pool = new WeakReference<>(pool);
            this.sleepTime = sleepTime;
            if (sleepTime <= 0) {
                log.warn("Database connection pool evicter thread interval is set to 0, defaulting to 30 seconds");
                this.sleepTime = 1000 * 30;
            } else if (sleepTime < 1000) {
                log.warn("Database connection pool evicter thread interval is set to lower than 1 second.");
            }
        }

        @Override
        public void run() {
            ConnectionPool pool = this.pool.get();
            if (pool == null) {
                stopRunning();
            } else if (!pool.isClosed()) {
                try {
                    if (pool.getPoolProperties().isRemoveAbandoned()
                            || pool.getPoolProperties().getSuspectTimeout() > 0)
                        pool.checkAbandoned();
                    if (pool.getPoolProperties().getMinIdle() < pool.idle
                            .size())
                        pool.checkIdle();
                    if (pool.getPoolProperties().isTestWhileIdle())
                        pool.testAllIdle();
                } catch (Exception x) {
                    log.error("", x);
                }
            }
        }

        public void start() {
            registerCleaner(this);
        }

        public void stopRunning() {
            unregisterCleaner(this);
        }
    }

相關參數

spring:
  datasource:
    tomcat:
      remove-abandoned: true
      # how long a connection should return,if not return regard as leak connection
      remove-abandoned-timeout: 10
      # how long a connection should return, or regard as probably leak connection
      suspect-timeout: 10
      log-abandoned: true
      abandon-when-percentage-full: 0 ## (used/max-active*100f)>=perc -->shouldAbandon, if set 0 always abandon

判斷條件

if (shouldAbandon() && (now - time) > con.getAbandonTimeout()) {
                        busy.remove(con);
                        abandon(con);
                        setToNull = true;
                    }
/**
     * Determines if a connection should be abandoned based on
     * {@link PoolProperties#abandonWhenPercentageFull} setting.
     * @return <code>true</code> if the connection should be abandoned
     */
    protected boolean shouldAbandon() {
        if (!poolProperties.isRemoveAbandoned()) return false;
        if (poolProperties.getAbandonWhenPercentageFull()==0) return true;
        float used = busy.size();
        float max  = poolProperties.getMaxActive();
        float perc = poolProperties.getAbandonWhenPercentageFull();
        return (used/max*100f)>=perc;
    }

這裏有個判斷條件，若是remove-abandoned=false，則不開啓
若是remove-abandoned=true且abandon-when-percentage-full=0，則開啓
若是remove-abandoned=true且abandon-when-percentage-full>0，則判斷(used/max*100f)>=perc
已經佔用的鏈接池數/max-active的比例是否是超過設定的閾值

ResetAbandonedTimer

這個的做用就是容許一個使用了很長時間的鏈接不由於超時而被abandon掉。它經過每次query來更新時間
tomcat-jdbc-8.5.11-sources.jar!/org/apache/tomcat/jdbc/pool/interceptor/ResetAbandonedTimer.java

public boolean resetTimer() {
        boolean result = false;
        JdbcInterceptor interceptor = this.getNext();
        while (interceptor!=null && result==false) {
            if (interceptor instanceof ProxyConnection) {
                PooledConnection con = ((ProxyConnection)interceptor).getConnection();
                if (con!=null) {
                    con.setTimestamp(System.currentTimeMillis());
                    result = true;
                } else {
                    break;
                }
            }
            interceptor = interceptor.getNext();
        }
        return result;
    }

這個通常用在單個鏈接上批處理的操做，好比jpa的批量save

spring-data-jpa-1.10.8.RELEASE-sources.jar!/org/springframework/data/jpa/repository/support/SimpleJpaRepository.java

@Transactional
    public <S extends T> List<S> save(Iterable<S> entities) {

        List<S> result = new ArrayList<S>();

        if (entities == null) {
            return result;
        }

        for (S entity : entities) {
            result.add(save(entity));
        }

        return result;
    }

這個批量save本質上是循環調用單個save

@Transactional
    public <S extends T> S save(S entity) {

        if (entityInformation.isNew(entity)) {
            em.persist(entity);
            return entity;
        } else {
            return em.merge(entity);
        }
    }

若是沒有設置ResetAbandonedTimer，則可能會由於abandon的設置致使鏈接被提早關閉收回，致使以下報錯

2017-07-07 16:08:21.821  WARN 6780 --- [:1499414841812]] o.a.tomcat.jdbc.pool.ConnectionPool      : Connection has been abandoned PooledConnection[org.postgresql.jdbc.PgConnection@4384b0e7]:java.lang.Exception
    at org.apache.tomcat.jdbc.pool.ConnectionPool.getThreadDump(ConnectionPool.java:1099)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:804)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:648)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:198)
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:132)
    at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122)
    at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:386)
    at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:87)
    at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getPhysicalConnection(LogicalConnectionManagedImpl.java:112)
    at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getConnectionForTransactionManagement(LogicalConnectionManagedImpl.java:230)
    at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.begin(LogicalConnectionManagedImpl.java:237)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.begin(JdbcResourceLocalTransactionCoordinatorImpl.java:214)
    at org.hibernate.engine.transaction.internal.TransactionImpl.begin(TransactionImpl.java:52)
    at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1512)
    at org.hibernate.jpa.internal.TransactionImpl.begin(TransactionImpl.java:45)
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:189)
    at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:380)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:447)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:277)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
    at com.sun.proxy.$Proxy128.save(Unknown Source)

2017-07-07 16:08:21.823  WARN 6780 --- [ qtp45320991-15] o.h.engine.jdbc.spi.SqlExceptionHelper   : SQL Error: 0, SQLState: null
2017-07-07 16:08:21.823 ERROR 6780 --- [ qtp45320991-15] o.h.engine.jdbc.spi.SqlExceptionHelper   : Connection has already been closed.
2017-07-07 16:08:21.866 ERROR 6780 --- [ qtp45320991-15] o.s.t.i.TransactionInterceptor           : Application exception overridden by rollback exception

javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: could not prepare statement
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1692) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1602) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1608) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.jpa.spi.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:1152) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
    at sun.reflect.GeneratedMethodAccessor100.invoke(Unknown Source) ~[na:na]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_71]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_71]

Caused by: java.sql.SQLException: Connection has already been closed.
    at org.apache.tomcat.jdbc.pool.ProxyConnection.invoke(ProxyConnection.java:117) ~[tomcat-jdbc-8.5.11.jar:na]
    at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108) ~[tomcat-jdbc-8.5.11.jar:na]
    at org.apache.tomcat.jdbc.pool.DisposableConnectionFacade.invoke(DisposableConnectionFacade.java:81) ~[tomcat-jdbc-8.5.11.jar:na]
    at com.sun.proxy.$Proxy86.prepareStatement(Unknown Source) ~[na:na]
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$1.doPrepare(StatementPreparerImpl.java:87) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:172) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
    ... 110 common frames omitted

2017-07-07 16:08:21.883  WARN 6780 --- [ qtp45320991-15] o.eclipse.jetty.servlet.ServletHandler   : 

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.transaction.TransactionSystemException: Could not roll back JPA transaction; nested exception is javax.persistence.PersistenceException: unexpected error when rollbacking
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982) ~[spring-webmvc-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) ~[javax.servlet-api-3.1.0.jar:3.1.0]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) ~[javax.servlet-api-3.1.0.jar:3.1.0]
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:848) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1772) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55) ~[spring-boot-1.4.5.RELEASE.jar:1.4.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:105) ~[spring-boot-actuator-1.4.5.RELEASE.jar:1.4.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:106) ~[spring-boot-actuator-1.4.5.RELEASE.jar:1.4.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1759) ~[jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:582) [jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548) [jetty-security-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:226) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512) [jetty-servlet-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.Server.handle(Server.java:534) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:320) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251) [jetty-server-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:283) [jetty-io-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110) [jetty-io-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93) [jetty-io-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303) [jetty-util-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148) [jetty-util-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136) [jetty-util-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671) [jetty-util-9.3.16.v20170120.jar:9.3.16.v20170120]
    at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589) [jetty-util-9.3.16.v20170120.jar:9.3.16.v20170120]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_71]
Caused by: org.springframework.transaction.TransactionSystemException: Could not roll back JPA transaction; nested exception is javax.persistence.PersistenceException: unexpected error when rollbacking
    at org.springframework.orm.jpa.JpaTransactionManager.doRollback(JpaTransactionManager.java:548) ~[spring-orm-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.processRollback(AbstractPlatformTransactionManager.java:853) ~[spring-tx-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.rollback(AbstractPlatformTransactionManager.java:830) ~[spring-tx-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.completeTransactionAfterThrowing(TransactionAspectSupport.java:522) ~[spring-tx-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:286) ~[spring-tx-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) ~[spring-tx-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136) ~[spring-tx-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133) ~[spring-data-jpa-1.10.8.RELEASE.jar:na]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) ~[spring-aop-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213) ~[spring-aop-4.3.7.RELEASE.jar:4.3.7.RELEASE]
    at com.sun.proxy.$Proxy128.save(Unknown Source) ~[na:na]

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• Tomcat 的 JDBC 鏈接池