我有一个tomcat服务器，它在Linux上有“太多打开文件”的问题。 我尝试通过将ulimit从4096增加到8192来修复它。
sudo vim /etc/security/limits.conf
* - nofile 8192
所以现在它看起来像这样：
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 23820
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 8192
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 8192
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
tomcat的进程限制是：
Limit Soft Limit Hard Limit Units
Max cpu time unlimited unlimited seconds
Max file size unlimited unlimited bytes
Max data size unlimited unlimited bytes
Max stack size 8388608 unlimited bytes
Max core file size 0 unlimited bytes
Max resident set unlimited unlimited bytes
Max processes 8192 23820 processes
Max open files 8192 8192 files
Max locked memory 65536 65536 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 23820 23820 signals
Max msgqueue size 819200 819200 bytes
Max nice priority 0 0
Max realtime priority 0 0
Max realtime timeout unlimited unlimited us
运行一段时间后，打开的文件增加到5000。 每当我尝试插入/更新数据时，它就会开始抛出异常：
2017-05-29 10:20:56 [org.hibernate.engine.jdbc.spi.SqlExceptionHelper]-[ERROR] - An attempt by a client to checkout a Connection has timed out.
2017-05-29 10:20:56 [mvc.controller.exception.resolver.Log4jExceptionResolver]-[DEBUG] - Resolving exception from handler [public java.lang.String mvc.controller.service.v2.HotTopicsPutController.put(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse,java.util.List<mvc.model.bean.form.v2.ArticleDataForm>,org.springframework.validation.BindingResult)]: org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
2017-05-29 10:20:56 [mvc.controller.exception.resolver.Log4jExceptionResolver]-[ERROR] - org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.springframework.orm.hibernate5.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:541)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:427)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:276)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
at com.sun.proxy.$Proxy29.insertOrUpdate(Unknown Source)
at mvc.controller.service.v2.HotTopicsPutController.put(HotTopicsPutController.java:60)
at sun.reflect.GeneratedMethodAccessor90.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:522)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:1110)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:785)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1425)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:102)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getPhysicalConnection(LogicalConnectionManagedImpl.java:129)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getConnectionForTransactionManagement(LogicalConnectionManagedImpl.java:247)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.begin(LogicalConnectionManagedImpl.java:254)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.begin(JdbcResourceLocalTransactionCoordinatorImpl.java:203)
at org.hibernate.engine.transaction.internal.TransactionImpl.begin(TransactionImpl.java:56)
at org.hibernate.internal.AbstractSharedSessionContract.beginTransaction(AbstractSharedSessionContract.java:401)
at org.springframework.orm.hibernate5.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:499)
... 50 more
Caused by: java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:65)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:527)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122)
at org.hibernate.internal.NonContextualJdbcConnectionAccess.obtainConnection(NonContextualJdbcConnectionAccess.java:35)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:99)
... 57 more
Caused by: com.mchange.v2.resourcepool.TimeoutException: A client timed out while waiting to acquire a resource from com.mchange.v2.resourcepool.BasicResourcePool@235ca7eb -- timeout at awaitAvailable()
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1317)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
... 61 more
看起来系统仍在阻止tomcat创建与数据库的连接。
这是我的server.xml和hibernate配置：
server.xml（仅允许https请求）
...
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
URIEncoding="UTF-8" useBodyEncodingForURI="true"
redirectPort="8443"/>
<Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol"
maxThreads="150" acceptCount="100" clientAuth="false"
scheme="https"
keystoreFile="/xxx/ooo/yyy"
keystorePass="xxxxxxxxxx"
keystoreType="xxxxxxx"
keyAlias="1"
secure="true" sslProtocol="TLS" SSLEnabled="true">
</Connector>
...
弹簧休眠：
<!-- Direct JDBC DataSource -->
<bean id="jdbcDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
destroy-method="close">
<property name="driverClass" value="com.mysql.cj.jdbc.Driver" />
...
<property name="minPoolSize" value="10" />
<property name="maxPoolSize" value="60" />
<property name="initialPoolSize" value="12" />
<property name="maxConnectionAge" value="1800" />
<property name="maxIdleTime" value="600" />
<property name="maxIdleTimeExcessConnections" value="300" />
<property name="idleConnectionTestPeriod" value="100" />
<property name="acquireIncrement" value="5" />
<property name="acquireRetryAttempts" value="30" />
<property name="acquireRetryDelay" value="1000" />
<property name="breakAfterAcquireFailure" value="false" />
<property name="checkoutTimeout" value="10000" />
<property name="testConnectionOnCheckout" value="false" />
<property name="preferredTestQuery" value="SELECT 1;" />
<property name="numHelperThreads" value="10" />
<property name="maxStatements" value="1000" />
<property name="maxStatementsPerConnection" value="25" />
...
</bean>
这是我的build.gradle：
// Spring framework
compile 'org.springframework:spring-context:4.3.2.RELEASE'
compile 'org.springframework:spring-context-support:4.3.2.RELEASE'
compile 'org.springframework.security:spring-security-web:4.1.1.RELEASE'
compile 'org.springframework.webflow:spring-webflow:2.4.4.RELEASE'
compile 'org.springframework.session:spring-session:1.2.1.RELEASE'
compile 'org.springframework.data:spring-data-jpa:1.10.2.RELEASE'
// Hibernate ORM
compile 'org.hibernate:hibernate-core:5.2.5.Final'
compile 'org.hibernate:hibernate-validator:5.2.4.Final'
compile 'com.mchange:c3p0:0.9.5.2'
compile 'javax.transaction:jta:1.1'
compile 'com.atomikos:transactions:4.0.4'
compile 'mysql:mysql-connector-java:6.0.3'
是否与keep alive sockets问题有关？
因为它从未减少，所以打开的文件数量不断增加。
我必须每周重启tomcat以关闭keep alive sockets。
我该怎么做才能解决这个问题？
为什么在增加打开文件限制后仍然存在问题？