tomcat jdbc连接池中的连接丢失

小编典典

tomcat jdbc连接池中的连接丢失

tomcat

我们只是从dbcp迁移到tomcat jdbc连接池。我们在加载中尝试了系统，并收到以下异常：

java.sql.SQLException: [IA1856] Timeout: Pool empty. Unable to fetch a connection in 1 seconds, none available[size:125; busy:90; idle:0; lastwait:1000].
        at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:632)
        at org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:174)
        at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:124)
        at com.inneractive.model.mappings.BasicPersistenceEntityMapping.getConnection(BasicPersistenceEntityMapping.java:233)
        at com.inneractive.model.mappings.BasicPersistenceEntityMapping.callWithConnection(BasicPersistenceEntityMapping.java:243)
        at com.inneractive.model.mappings.PersistenceEntityMapping.get(PersistenceEntityMapping.java:194)
        at com.inneractive.model.data.client.ClientUtils.GetClientByExamples(ClientUtils.java:353)
        at com.inneractive.client.ExternalAdRingsClientStart.getClientInfoByRequestParametersOrInsert(ExternalAdRingsClientStart.java:1329)
        at com.inneractive.client.ExternalAdRingsClientStart.newClientSession(ExternalAdRingsClientStart.java:245)
        at com.inneractive.simpleM2M.web.SimpleM2MProtocolBean.generateCampaign(SimpleM2MProtocolBean.java:235)
        at com.inneractive.simpleM2M.web.SimpleM2MProtocolBean.generateCampaign(SimpleM2MProtocolBean.java:219)
        at com.inneractive.simpleM2M.web.AdsServlet.doGet(AdsServlet.java:175)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:555)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
        at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:396)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:662)

请注意：

[size:125; busy:90; idle:0; lastwait:1000]

不忙的连接在哪里？此后，忙碌号码一直在下降，但是我们仍然没有设法建立任何连接。

有任何想法吗？

组态：

<Resource auth="Container" driverClassName="com.mysql.jdbc.Driver"
                factory="org.apache.tomcat.jdbc.pool.DataSourceFactory" loginTimeout="10000"
                maxActive="35" maxIdle="35" maxWait="1000" name="jdbc/mysql"
                password="-----" testOnBorrow="true" testOnReturn="false" type="javax.sql.DataSource"
                url="jdbc:mysql://localhost:3306/my_db?elideSetAutoCommits=true&amp;useDynamicCharsetInfo=false&amp;rewriteBatchedStatements=true&amp;useLocalSessionState=true&amp;useLocalTransactionState=true&amp;alwaysSendSetIsolation=false&amp;cacheServerConfiguration=true&amp;noAccessToProcedureBodies=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"
                username="root" validationQuery="SELECT 1"/>

env：ubuntu和tomcat6。数据库-mysql

阅读 303

2020-06-16

共1个答案

小编典典

看一下ConnectionPool.java的源代码，您似乎在borrowConnection()方法中点击了以下代码片段：

        //we didn't get a connection, lets see if we timed out
        if (con == null) {
            if ((System.currentTimeMillis() - now) >= maxWait) {
                throw new SQLException("[" + Thread.currentThread().getName()+"] " +
                    "Timeout: Pool empty. Unable to fetch a connection in " + (maxWait / 1000) +
                    " seconds, none available["+busy.size()+" in use].");
            } else {
                //no timeout, lets try again
                continue;
            }
        }

因此，据此，您的连接为 Null 。

con在以下行中检索的值：

PooledConnection con = idle.poll();

如果您跟踪代码，则将看到idle（取决于您的配置，但默认情况下）FairBlockingQueue。您可以检查实现以获取提示。

通常，您始终必须关闭ResultSet，语句和连接，并且使用的连接应正确释放回池中。如果操作不正确，可能会导致连接永不关闭=>不再可供重用（连接池“泄漏”）。

我建议您构造一些有关池状态的详细日志记录，并对其进行监视以找出问题所在。

Apache的一些防止数据库连接池泄漏的准则：

removeAbandoned="true"

废弃的数据库连接被删除并回收

removeAbandonedTimeout="60"

设置数据库连接空闲之前被认为已放弃的秒数

logAbandoned="true"

记录放弃了数据库连接资源的代码的堆栈跟踪。请记住，“记录废弃的连接会增加每次连接借用的开销，因为必须生成堆栈跟踪。”

我仍然认为稍微增加该maxWait值（1200、1500、1700-仅作实验，从用户角度来看响应时间没有差异）将清除那些仍然存在问题的罕见情况。

2020-06-16