com.mysql.jdbc.exceptions.jdbc4.CommunicationsException MySQL + Apache Tomcat 7

Question

La mia applicazione (Spring 4 MVC/Hibernate 4/MySQL/Maven) integra Spring con Hibernate utilizzando la configurazione basata su annotazioni. Dopo alcune ore di non utilizzo del database vedo sempre questo errore:

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 84,510,841 milliseconds ago. The last packet sent successfully to the server was 84,510,841 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem. 
    sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
    sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) 
    sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) 
    java.lang.reflect.Constructor.newInstance(Constructor.java:526) 
    com.mysql.jdbc.Util.handleNewInstance(Util.java:411) 
    com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121) 
    com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3938) 
    com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2551) 
    com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2731) 
    com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2809) 
    com.mysql.jdbc.ConnectionImpl.setAutoCommit(ConnectionImpl.java:5333) 
    sun.reflect.GeneratedMethodAccessor58.invoke(Unknown Source) 
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    java.lang.reflect.Method.invoke(Method.java:606) 
    org.apache.tomcat.jdbc.pool.ProxyConnection.invoke(ProxyConnection.java:126) 
    org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:109) 
    org.apache.tomcat.jdbc.pool.DisposableConnectionFacade.invoke(DisposableConnectionFacade.java:80) 
    com.sun.proxy.$Proxy33.setAutoCommit(Unknown Source) 
    org.hibernate.resource.jdbc.internal.AbstractLogicalConnectionImplementor.begin(AbstractLogicalConnectionImplementor.java:67) 
    org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.begin(LogicalConnectionManagedImpl.java:238) 
    org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.begin(JdbcResourceLocalTransactionCoordinatorImpl.java:213) 
    org.hibernate.engine.transaction.internal.TransactionImpl.begin(TransactionImpl.java:52) 
    org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1512) 
    org.hibernate.jpa.internal.TransactionImpl.begin(TransactionImpl.java:45) 
    org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:170) 
    org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:380) 
    org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373) 
    org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:427) 
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:276) 
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) 
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) 
    org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208) 
    com.sun.proxy.$Proxy118.findAll(Unknown Source) 
    com.ideefe.iot.controller.AppController.listDevices(AppController.java:49) 
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    java.lang.reflect.Method.invoke(Method.java:606) 
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222) 
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) 
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) 
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814) 
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737) 
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) 
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) 
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) 
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) 
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:620) 
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) 
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727) 
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) 
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) 
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) 
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) 
    org.springframework.web.multipart.support.MultipartFilter.doFilterInternal(MultipartFilter.java:118) 
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) 

Ecco il file di MySQL my.cnf:

devuser@localhost:/etc/apache2$ more /etc/mysql/my.cnf 
# 
# The MySQL database server configuration file. 
# 
# You can copy this to one of: 
# - "/etc/mysql/my.cnf" to set global options, 
# - "~/.my.cnf" to set user-specific options. 
# 
# One can use all long options that the program supports. 
# Run program with --help to get a list of available options and with 
# --print-defaults to see which it would actually understand and use. 
# 
# For explanations see 
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html 

# This will be passed to all mysql clients 
# It has been reported that passwords should be enclosed with ticks/quotes 
# escpecially if they contain "#" chars... 
# Remember to edit /etc/mysql/debian.cnf when changing the socket location. 
[client] 
port  = 3306 
socket  = /var/run/mysqld/mysqld.sock 

# Here is entries for some specific programs 
# The following values assume you have at least 32M ram 

# This was formally known as [safe_mysqld]. Both versions are currently parsed. 
[mysqld_safe] 
socket  = /var/run/mysqld/mysqld.sock 
nice  = 0 

[mysqld] 
# 
# * Basic Settings 
# 
user  = mysql 
pid-file = /var/run/mysqld/mysqld.pid 
socket  = /var/run/mysqld/mysqld.sock 
port  = 3306 
basedir  = /usr 
datadir  = /var/lib/mysql 
tmpdir  = /tmp 
lc-messages-dir = /usr/share/mysql 
skip-external-locking 
# 
# Instead of skip-networking the default is now to listen only on 
# localhost which is more compatible and is not less secure. 
bind-address  = 127.0.0.1 
# 
# * Fine Tuning 
# 
key_buffer  = 32M 
max_allowed_packet = 1M 
thread_stack  = 128K 
thread_cache_size  = 8 
# This replaces the startup script and checks MyISAM tables if needed 
# the first time they are touched 
myisam-recover   = BACKUP 
max_connections  = 75 
table_cache   = 32 
#thread_concurrency  = 10 
# 
# * Query Cache Configuration 
# 
query_cache_limit = 1M 
query_cache_size  = 16M 
# 
# * Logging and Replication 
# 
# Both location gets rotated by the cronjob. 
# Be aware that this log type is a performance killer. 
# As of 5.1 you can enable the log at runtime! 
#general_log_file  = /var/log/mysql/mysql.log 
#general_log    = 1 
# 
# Error log - should be very few entries. 
# 
log_error = /var/log/mysql/error.log 
# 
# Here you can see queries with especially long duration 
#log_slow_queries = /var/log/mysql/mysql-slow.log 
#long_query_time = 2 
#log-queries-not-using-indexes 
# 
# The following can be used as easy to replay backup logs or for replication. 
# note: if you are setting up a replication slave, see README.Debian about 
#  other settings you may need to change. 
#server-id  = 1 
#log_bin   = /var/log/mysql/mysql-bin.log 
expire_logs_days = 10 
max_binlog_size   = 100M 
#binlog_do_db  = include_database_name 
#binlog_ignore_db = include_database_name 
# 
# * InnoDB 
# 
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. 
# Read the manual for more InnoDB related options. There are many! 
# 
# * Security Features 
# 
# Read the manual, too, if you want chroot! 
# chroot = /var/lib/mysql/ 
# 
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca". 
# 
# ssl-ca=/etc/mysql/cacert.pem 
# ssl-cert=/etc/mysql/server-cert.pem 
# ssl-key=/etc/mysql/server-key.pem 



[mysqldump] 
quick 
quote-names 
max_allowed_packet = 16M 

[mysql] 
#no-auto-rehash # faster start of mysql but no tab completition 

[isamchk] 
key_buffer  = 16M 

# 
# * IMPORTANT: Additional settings that can override those from this file! 
# The files must end with '.cnf', otherwise they'll be ignored. 
# 
!includedir /etc/mysql/conf.d/ 

Sto usando un pool di connessioni definito come segue:

<?xml version="1.0" encoding="UTF-8"?> 
<Context> 
    <!-- Especifica un DataSource JDBC. --> 
    <Resource name="jdbc/devicesDS" 
       auth="Container" 
       type="javax.sql.DataSource" 
       maxActive="10" 
       maxIdle="4" 
       username="root" 
       password="SrbBfsatn640^" 
       driverClassName="com.mysql.jdbc.Driver" 
       url="jdbc:mysql://localhost:3306/devices?autoReconnect=true" 
       validationQuery="select 1 from dual" /> 
</Context> 

Answer 1

Sembra che questo sia lo - ci sono alcune domande simili StackOverflow (es. here, here e here). Lo consigliamo vivamente modificando le impostazioni del pool di connessioni con l'aggiunta di testOnBorrow=true, cioè:

<Resource name="jdbc/devicesDS" 
      auth="Container" 
      type="javax.sql.DataSource" 
      maxActive="10" 
      maxIdle="4" 
      username="root" 
      password="SrbBfsatn640^" 
      driverClassName="com.mysql.jdbc.Driver" 
      url="jdbc:mysql://localhost:3306/devices?autoReconnect=true" 
      validationQuery="select 1 from dual" 
      testOnBorrow=true /> 

personalmente inclinarsi verso testOnBorrow sopra l'alternativa di testWhileIdle dal momento che il primo è completamente indipendente dal valore wait_timeout - ma non sono sicuro di come le prestazioni a confronto. Sarebbe personalmente prudente nell'usare l'alternativa di autoreconnect=true nell'URL JDBC, suggerita nel testo dell'errore - vedere comment here per il motivo.

Answer 2

Nella propria applicazione la stringa di connessione al database mysql dovrebbe essere:

jdbc:mysql://{host}:{port}/{schema}?autoReconnect=true 

aggiungendo Autoreconnect = true risolverà questo problema

Answer 3

mi entrano questo problema con altre implementazioni di applicazioni, dopo tryed ogni config , autoreconnect, ecc. L'unico modo che ho trovato per risolvere questo è stato fare un evento di pianificazione che chiama una query di prova ogni ora per eseguire il ping del DB, costringendolo a aggiornare la connessione.

query("SELECT version()");