Grails 2.2 and MySQL: java.net.SocketException: Connection reset - mysql

Question

I get java.net.SocketException: Connection reset from a pool thread.
Sometimes my application is able to get the data from the database.
I didn't have this issue when I had a smaller number of hosts to query.
ERROR [JDBCTransaction] JDBC begin failed
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:696)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1102)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2336)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2369)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2153)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38)
at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582)
at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1181)
at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:106)
at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:189)
at java.net.SocketInputStream.read(SocketInputStream.java:121)
at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:114)
at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:161)
at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:189)
at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:2549)
at com.mysql.jdbc.MysqlIO.readPacket(MysqlIO.java:620)
... 17 more
Using Grails 2.2.4 on Tomcat 7.0.47, MySQL Connector 5.1.18, MySQL 5.5.12, Windows Server 2003.
Have around 100 hosts that are queried with JMX every 2min, and SMB every 1h.
Using default pooling from DBCP. The code issues multiple threads in a loop, one for each remote host (TCP connections).
Max_used_connections in MySQL shows 503 and is near the limit set in DataSource.groovy (maxActive = 500), but I don't get "too many connections" exception.
I have those "testOn*" properties set in DataSource.groovy.
I tried increasing the number of available ports (Windows Server 2003) to 10000 and decreasing TIME_WAIT to 30, but to no avail.
One more thing
Some time ago this kind of exception has started to appear (every < 100ms) when Grails is doing an automatic validation on domain objects in a background thread that has no Hibernate session
[pool-10-thread-23066] ERROR StackTrace - Full Stack Trace:
org.hibernate.HibernateException: No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here
at org.springframework.orm.hibernate3.SpringSessionContext.currentSession(SpringSessionContext.java:63)
at org.hibernate.impl.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:687)
at org.codehaus.groovy.grails.orm.hibernate.validation.HibernateDomainClassValidator.validate(HibernateDomainClassValidator.java:51)
at org.codehaus.groovy.grails.validation.GrailsDomainClassValidator.validate(GrailsDomainClassValidator.java:120)
at org.codehaus.groovy.grails.orm.hibernate.metaclass.ValidatePersistentMethod.doInvokeInternal(ValidatePersistentMethod.java:119)
at org.codehaus.groovy.grails.orm.hibernate.metaclass.AbstractDynamicPersistentMethod.invoke(AbstractDynamicPersistentMethod.java:63)
at sun.reflect.GeneratedMethodAccessor499.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSite.invoke(PojoMetaMethodSite.java:189)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:124)
at org.codehaus.groovy.grails.orm.hibernate.HibernateGormValidationApi.validate(HibernateGormEnhancer.groovy:731)
at xx.xx.xx.xxVO.validate(xxVO.groovy)
at sun.reflect.GeneratedMethodAccessor573.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)
at org.codehaus.groovy.grails.orm.hibernate.support.ClosureEventListener$7.call(ClosureEventListener.java:282)
at org.codehaus.groovy.grails.orm.hibernate.support.ClosureEventListener$7.call(ClosureEventListener.java:267)
at org.codehaus.groovy.grails.orm.hibernate.support.ClosureEventListener.doWithManualSession(ClosureEventListener.java:302)
at org.codehaus.groovy.grails.orm.hibernate.support.ClosureEventListener.onPreUpdate(ClosureEventListener.java:267)
at org.codehaus.groovy.grails.orm.hibernate.EventTriggeringInterceptor.onPreUpdate(EventTriggeringInterceptor.java:175)
at org.codehaus.groovy.grails.orm.hibernate.EventTriggeringInterceptor.onPersistenceEvent(EventTriggeringInterceptor.java:100)
at org.grails.datastore.mapping.engine.event.AbstractPersistenceEventListener.onApplicationEvent(AbstractPersistenceEventListener.java:47)
at org.springframework.context.event.SimpleApplicationEventMulticaster$1.run(SimpleApplicationEventMulticaster.java:92)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
I ignored it then, but maybe it has something to do with this.
Does anybody have any pointers as to what the cause of this might be and how to avoid it?

Answer 1

The initial exception I got before I started tweaking things was:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The driver was unable to create a connection due to an inability to establish the client portion of a socket.
This is usually caused by a limit on the number of sockets imposed by the operating system. This limit is usually configurable.
For Unix-based platforms, see the manual page for the 'ulimit' command. Kernel or system reconfiguration may also be required.
For Windows-based platforms, see Microsoft Knowledge Base Article 196271 (Q196271).
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:344)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2332)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2369)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2153)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:38)
at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:582)
at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1181)
at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:106)
at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.net.BindException: Address already in use: connect
at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391)
at java.net.Socket.connect(Socket.java:579)
at java.net.Socket.connect(Socket.java:528)
at java.net.Socket.<init>(Socket.java:425)
at java.net.Socket.<init>(Socket.java:241)
at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:257)
at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:294)
... 16 more
And the issue here is TCP port exhaustion. Increasing MaxUserPort and decreasing TcpTimedWaitDelay in the OS registry solved it.