我们的项目中有 Spring-boot/Hibernate/PostgreSQL 应用程序，并使用 Hikari 作为连接池。 我们不断遇到以下问题：几个小时后，活动连接数增长到极限，我们收到这样的错误（完整的堆栈跟踪位于问题的末尾）：
Caused by: java.sql.SQLTransientConnectionException: HikariPool-0 - Connection is not available, request timed out after 30000ms.
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:213) ~[HikariCP-2.4.1.jar:na]
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:163) ~[HikariCP-2.4.1.jar:na]
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:85) ~[HikariCP-2.4.1.jar:na]
at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:139) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:380) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:228) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
... 126 common frames omitted
这是版本信息：
Spring-boot version: 1.2.3.RELEASE
HikariCP version: 2.4.1
Hibernate version: 4.3.6.Final
Postgresql jdbc: 9.3-1102-jdbc41
Server version: Apache Tomcat/8.0.23
JVM Version: 1.8.0_45-b14
JPA/Hibernate 配置：
jpa:
database-platform: org.hibernate.dialect.PostgreSQL82Dialect
database: POSTGRESQL
openInView: false
show_sql: false
generate-ddl: false
hibernate:
ddl-auto: none
naming-strategy: org.hibernate.cfg.EJB3NamingStrategy
properties:
hibernate.cache.use_second_level_cache: true
hibernate.cache.use_query_cache: false
hibernate.generate_statistics: false
hibernate.cache.region.factory_class: org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory
hibernate.enable_lazy_load_no_trans: true
hibernate.event.merge.entity_copy_observer: allow
HikariCP 配置：
2015-10-06 12:26:44,252 DEBUG [localhost-startStop-1] HikariConfig: HikariPool-0 - configuration:
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: allowPoolSuspension.............false
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: autoCommit......................true
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: catalog.........................
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: connectionInitSql...............
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: connectionTestQuery.............
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: connectionTimeout...............30000
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: dataSource......................
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: dataSourceClassName.............org.postgresql.ds.PGSimpleDataSource
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: dataSourceJNDI..................
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: dataSourceProperties............{user=postgres, password=<masked>, databaseName=lms, serverName=*.*.*.*:5432}
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: driverClassName.................
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: healthCheckProperties...........{}
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: healthCheckRegistry.............
2015-10-06 12:26:44,274 DEBUG [localhost-startStop-1] HikariConfig: idleTimeout.....................30000
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: initializationFailFast..........true
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: isolateInternalQueries..........false
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: jdbc4ConnectionTest.............false
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: jdbcUrl.........................
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: leakDetectionThreshold..........0
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: maxLifetime.....................1800000
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: maximumPoolSize.................20
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: metricRegistry..................com.codahale.metrics.MetricRegistry@63d2fc48
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: metricsTrackerFactory...........
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: minimumIdle.....................10
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: password........................<masked>
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: poolName........................HikariPool-0
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: readOnly........................false
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: registerMbeans..................false
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: scheduledExecutorService........
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: threadFactory...................
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: transactionIsolation............
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: username........................
2015-10-06 12:26:44,275 DEBUG [localhost-startStop-1] HikariConfig: validationTimeout...............5000
2015-10-06 12:26:44,276 INFO [localhost-startStop-1] HikariDataSource: HikariPool-0 - is starting.
2015-10-06 12:26:44,432 DEBUG [localhost-startStop-1] PoolElf: HikariPool-0 - Connection.setNetworkTimeout() is not supported (Method org.postgresql.jdbc4.Jdbc4Connection.getNetworkTimeout() is not yet implemented.)
完整堆栈跟踪：
2015-10-06 12:09:36,885 DEBUG [http-nio-8080-exec-25] PoolElf: HikariPool-0 - Reset (nothing) on connection org.postgresql.jdbc4.Jdbc4Connection@3cc4d919
2015-10-06 12:09:42,651 DEBUG [Hikari housekeeper (pool HikariPool-0)] HikariPool: Before cleanup pool HikariPool-0 stats (total=20, active=20, idle=0, waiting=1)
2015-10-06 12:09:42,652 DEBUG [Hikari housekeeper (pool HikariPool-0)] HikariPool: After cleanup pool HikariPool-0 stats (total=20, active=20, idle=0, waiting=1)
2015-10-06 12:10:06,885 DEBUG [http-nio-8080-exec-25] HikariPool: Timeout failure pool HikariPool-0 stats (total=20, active=20, idle=0, waiting=0)
2015-10-06 12:10:06,885 WARN [http-nio-8080-exec-25] SqlExceptionHelper: SQL Error: 0, SQLState: null
2015-10-06 12:10:06,885 ERROR [http-nio-8080-exec-25] SqlExceptionHelper: HikariPool-0 - Connection is not available, request timed out after 30000ms.
2015-10-06 12:10:06,885 DEBUG [http-nio-8080-exec-25] PoolElf: HikariPool-0 - Reset (nothing) on connection org.postgresql.jdbc4.Jdbc4Connection@3cc4d919
2015-10-06 12:10:06,886 ERROR [http-nio-8080-exec-25] ErrorPageFilter: Forwarding to error page from request [/api/courses/121387/quizzes/i6fa2562510bf8578712380a87a433e97/student/30175] due to exception [org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.exception.JDBCConnectionException: Could not open connection]
java.lang.RuntimeException: org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.exception.JDBCConnectionException: Could not open connection
at lms.security.xauth.XAuthTokenFilter.doFilter(XAuthTokenFilter.java:86) ~[XAuthTokenFilter.class:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:120) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:64) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:91) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:53) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:213) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:176) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:102) ~[spring-boot-actuator-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:85) ~[spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.springframework.boot.context.web.ErrorPageFilter.doFilter(ErrorPageFilter.java:113) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.boot.context.web.ErrorPageFilter.access$000(ErrorPageFilter.java:59) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.boot.context.web.ErrorPageFilter$1.doFilterInternal(ErrorPageFilter.java:88) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.boot.context.web.ErrorPageFilter.doFilter(ErrorPageFilter.java:106) [spring-boot-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) [catalina.jar:8.0.23]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [catalina.jar:8.0.23]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [catalina.jar:8.0.23]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) [catalina.jar:8.0.23]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [catalina.jar:8.0.23]
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617) [catalina.jar:8.0.23]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [catalina.jar:8.0.23]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) [catalina.jar:8.0.23]
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) [tomcat-coyote.jar:8.0.23]
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668) [tomcat-coyote.jar:8.0.23]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521) [tomcat-coyote.jar:8.0.23]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478) [tomcat-coyote.jar:8.0.23]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_45]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_45]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.0.23]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_45]
Caused by: org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.exception.JDBCConnectionException: Could not open connection
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:868) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648) ~[servlet-api.jar:na]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[servlet-api.jar:na]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at com.codahale.metrics.servlet.AbstractInstrumentedFilter.doFilter(AbstractInstrumentedFilter.java:104) ~[metrics-servlet-3.1.1.jar:3.1.1]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-websocket.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:291) ~[spring-boot-actuator-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [catalina.jar:8.0.23]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [catalina.jar:8.0.23]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:316) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:114) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:122) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:168) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:48) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) ~[spring-security-web-4.0.0.RELEASE.jar:na]
at lms.security.xauth.XAuthTokenFilter.doFilter(XAuthTokenFilter.java:84) ~[XAuthTokenFilter.class:na]
... 46 common frames omitted
Caused by: org.hibernate.exception.JDBCConnectionException: Could not open connection
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:65) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:235) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:171) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:67) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:162) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1435) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:250) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.collection.internal.AbstractPersistentCollection.readElementByIndex(AbstractPersistentCollection.java:376) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.collection.internal.PersistentMap.get(PersistentMap.java:164) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at java_util_Map$get.call(Unknown Source) ~[na:na]
at lms.service.QuizService.processAnswers(QuizService.groovy:66) ~[QuizService.class:na]
at lms.service.QuizService$$FastClassBySpringCGLIB$$4dcc8beb.invoke(<generated>) ~[spring-core-4.1.6.RELEASE.jar:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) ~[spring-tx-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281) ~[spring-tx-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) ~[spring-tx-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at lms.service.QuizService$$EnhancerBySpringCGLIB$$37a60c0a.processAnswers(<generated>) ~[spring-core-4.1.6.RELEASE.jar:na]
at lms.web.rest.CourseResource.saveQuizResults(CourseResource.java:537) ~[CourseResource.class:na]
at lms.web.rest.CourseResource$$FastClassBySpringCGLIB$$e3d2ba4d.invoke(<generated>) ~[spring-core-4.1.6.RELEASE.jar:na]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:68) ~[spring-security-core-4.0.0.RELEASE.jar:na]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at com.ryantenney.metrics.spring.TimedMethodInterceptor.invoke(TimedMethodInterceptor.java:48) ~[metrics-spring-3.0.4.jar:na]
at com.ryantenney.metrics.spring.TimedMethodInterceptor.invoke(TimedMethodInterceptor.java:34) ~[metrics-spring-3.0.4.jar:na]
at com.ryantenney.metrics.spring.AbstractMetricMethodInterceptor.invoke(AbstractMetricMethodInterceptor.java:59) ~[metrics-spring-3.0.4.jar:na]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653) ~[spring-aop-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at lms.web.rest.CourseResource$$EnhancerBySpringCGLIB$$ff854301.saveQuizResults(<generated>) ~[spring-core-4.1.6.RELEASE.jar:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_45]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_45]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_45]
at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_45]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:776) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:705) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966) ~[spring-webmvc-4.1.6.RELEASE.jar:4.1.6.RELEASE]
... 81 common frames omitted
Caused by: java.sql.SQLTransientConnectionException: HikariPool-0 - Connection is not available, request timed out after 30000ms.
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:213) ~[HikariCP-2.4.1.jar:na]
at com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:163) ~[HikariCP-2.4.1.jar:na]
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:85) ~[HikariCP-2.4.1.jar:na]
at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:139) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:380) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:228) ~[hibernate-core-4.3.6.Final.jar:4.3.6.Final]
... 126 common frames omitted
2015-10-06 12:10:12,651 DEBUG [Hikari housekeeper (pool HikariPool-0)] HikariPool: Before cleanup pool HikariPool-0 stats (total=20, active=19, idle=1, waiting=0)
2015-10-06 12:10:12,652 DEBUG [Hikari housekeeper (pool HikariPool-0)] HikariPool: After cleanup pool HikariPool-0 stats (total=20, active=19, idle=1, waiting=0)
任何线索都会有帮助！
我终于修好了。该问题与 HikariCP 无关。 由于 REST 控制器中的一些复杂方法通过 JPA 存储库在数据库中执行多个更改，因此问题仍然存在。由于某些原因，对这些接口的调用导致“冻结”活动连接数量不断增加，从而耗尽池。将这些方法注释为
@Transactional来自堆栈跟踪：
HikariPool：超时失败池 HikariPool-0 统计信息（总计 = 20，活动 = 20，空闲 = 0，等待 = 0） 意味着池达到配置中设置的最大连接限制。
下一行： HikariPool-0 - 连接不可用，请求在 30000 毫秒后超时。 意味着池等待 30000 毫秒的免费连接，但您的应用程序在此期间没有返回任何连接。
主要是连接泄漏（从池中借用连接后未关闭）， 将leakDetectionThreshold 设置为您期望执行SQL 查询所需的最大值。
否则， 您“一次”的最大连接数要求高于 20！
通过将以下属性添加到 application.properties 文件中，问题已解决：
spring.datasource.hikari.connection-test-query=SELECT 1 FROM DUAL
spring.datasource.hikari.connection-timeout=600000
spring.datasource.hikari.maximum-pool-size=500
spring.datasource.hikari.max-lifetime=1800000
spring.datasource.hikari.minimum-idle=20
spring.datasource.hikari.validation-timeout=3000
spring.datasource.hikari.idle-timeout=60000
我有一个类似的问题，罪魁祸首原来是使用jdbc的“queryForStream”。更多信息请参见下面的文章，但本质上您需要显式关闭流或连接保持打开状态。
https://mjchi7.github.io/posts/jdbctemplate-queryforstream-connection-leak/
我在与同事合作的项目中遇到了同样的问题。他正在使用 jdbc，并且在完成后忘记关闭一些数据库连接。这引发了这个错误。如果您不使用 Hibernate 或 JDBC 模板，请确保关闭每个数据库连接。 访问此网站获取更多示例 https://mkyong.com/jdbc/hikaripool-1-connection-is-not-available-request-timed-out-after-30002ms/
AO_提到的VPN问题是很常见但却被忽视的一个。
可能的原因之一可能是某人正在从服务器请求资源，而该请求被组织的 VPN 阻止。在这种情况下，可以尝试通过 VPN 连接。我过去也发生过这样的事。在分布式工作文化中，这种情况可能会在多种情况下发生，主要是当互联网连接丢失/重置从而与 VPN 断开连接时。在这种情况下，唯一的方法是在互联网连接恢复后重新连接到 VPN。
我正在使用JdbcClient（springboot 3.2，java 21）并想立即处理查询结果。
List<BigDecimal> out = jdbcClient
.sql("""
SELECT DISTINCT percent
FROM order
WHERE active=true
""")
.query((rs, __) -> rs.getBigDecimal("percent"))
.stream()
.map(bd -> bd.multiply(_100))
.map(bd -> bd.setScale(0, RoundingMode.HALF_UP))
.toList();
看起来不错，但很快我就收到了有关缺少数据库连接的消息。
启用日志记录：
<logger name="com.zaxxer.hikari.pool" level="DEBUG" />
[HikariPool-1 housekeeper] WARN c.zaxxer.hikari.pool.ProxyLeakTask [] - Connection leak detection triggered for org.postgresql.jdbc.PgConnection@67e11bda on thread http-nio-8082-exec-3, stack trace follows
java.lang.Exception: Apparent connection leak detected
at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:128)
at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:160)
at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:118)
at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:81)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:653)
at org.springframework.jdbc.core.JdbcTemplate.queryForStream(JdbcTemplate.java:844)
at org.springframework.jdbc.core.JdbcTemplate.queryForStream(JdbcTemplate.java:863)
at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.queryForStream(NamedParameterJdbcTemplate.java:237)
at org.springframework.jdbc.core.simple.DefaultJdbcClient$DefaultStatementSpec$NamedParamMappedQuerySpec.stream(DefaultJdbcClient.java:361)
at pl.apinn.jflowers.DiscountController.ordersClientFromYear(DiscountController.java:59)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:578)
线：(DiscountController.java:59)
指向
.stream()
所以我在数据库查询上添加了一个终端操作：.list()
，它有帮助：
List<BigDecimal> out = jdbcClient
.sql("""
SELECT DISTINCT percent
FROM order
WHERE active=true
""")
.query((rs, __) -> rs.getBigDecimal("percent"))
.list()
.stream()
.map(bd -> bd.multiply(_100))
.map(bd -> bd.setScale(0, RoundingMode.HALF_UP))
.toList();