hibernate报Communications link failure

Question

hiberate偶尔会报错Communications link failure，并出现以下错误

[WARN ] 2017-07-28 09:48:12,876 org.hibernate.util.JDBCExceptionReporter SQL Error: 0, SQLState: 08S01
[ERROR] 2017-07-28 09:48:12,879 org.hibernate.util.JDBCExceptionReporter Communications link failure

The last packet successfully received from the server was 51,384 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago.

org.hibernate.exception.JDBCConnectionException: Cannot open connection
        at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99)
        at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
        at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
        at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
        at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
        at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:160)
        at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:81)
        at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1473)
        at sun.reflect.GeneratedMethodAccessor54.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:345)
        at com.sun.proxy.$Proxy46.beginTransaction(Unknown Source)
        at com.bwton.info.usermanager.dao.UserDAO.queryByMainKey(UserDAO.java:45)
        at com.bwton.info.usermanager.service.PhoneService.authByPwd(PhoneService.java:105)
        at com.bwton.info.usermanager.servlet.Auth.doPost(Auth.java:88)
        at com.bwton.info.usermanager.servlet.Auth.doGet(Auth.java:41)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at com.bwton.info.usermanager.servlet.LoginFilter.doFilter(LoginFilter.java:95)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:506)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1115)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
        at org.apache.tomcat.util.net.AprEndpoint$SocketWithOptionsProcessor.run(AprEndpoint.java:2486)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:748)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet successfully received from the server was 51,384 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
        at com.mysql.jdbc.Util.handleNewInstance(Util.java:404)
        at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:988)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3552)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3452)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3893)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2526)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2673)
        at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545)
        at com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:4842)
        at com.mchange.v2.c3p0.impl.NewProxyConnection.setAutoCommit(NewProxyConnection.java:1059)
        at org.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:83)
        at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
        ... 38 more
Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
        at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:3004)
        at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:3462)
        ... 47 more

c3p0和hibernate配置如下

<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">
        jdbc:mysql://localhost:3306/testdb?useUnicode=true&amp;characterEncoding=UTF-8&amp;autoReconnect=true
</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">123456</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<property name="hibernate.current_session_context_class">thread</property>
<property name="hibernate.connection.provider_class">
    org.hibernate.connection.C3P0ConnectionProvider
</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.min_size">1</property>
<property name="hibernate.c3p0.timeout">1800</property>
<property name="hibernate.c3p0.acquire_increment">1</property>
<property name="hibernate.c3p0.max_statements">10</property>
<property name="hibernate.c3p0.idle_test_period">100</property>

mysql的TimeOut如下

wait_timeout远小于c3p0的idle_test_period，百度之后并没有发现相关的解决方法。

Answer 1

mysql client链接看看