Java ApacheCayenne/PostgreSQL:“；已经有太多的客户了”；错误

我使用的是Apache Cayenne 4 Milestone 5，我遇到了这个错误。该应用程序尚未正式部署，但正在IntelliJ IDEA中进行测试

Apr 03, 2017 10:19:58 PM org.postgresql.Driver connect
SEVERE: Connection error: 
org.postgresql.util.PSQLException: FATAL: sorry, too many clients already
    at org.postgresql.core.v3.ConnectionFactoryImpl.doAuthentication(ConnectionFactoryImpl.java:438)
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:222)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:49)
    at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:194)
    at org.postgresql.Driver.makeConnection(Driver.java:431)
    at org.postgresql.Driver.connect(Driver.java:247)
    at org.apache.cayenne.datasource.DriverDataSource.getConnection(DriverDataSource.java:159)
    at org.apache.cayenne.datasource.DriverDataSource.getConnection(DriverDataSource.java:133)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.createUnwrapped(UnmanagedPoolingDataSource.java:300)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.createWrapped(UnmanagedPoolingDataSource.java:293)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.createUnchecked(UnmanagedPoolingDataSource.java:273)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.<init>(UnmanagedPoolingDataSource.java:142)
    at org.apache.cayenne.datasource.PoolingDataSourceBuilder.buildPooling(PoolingDataSourceBuilder.java:92)
    at org.apache.cayenne.datasource.PoolingDataSourceBuilder.build(PoolingDataSourceBuilder.java:88)
    at org.apache.cayenne.configuration.server.XMLPoolingDataSourceFactory.getDataSource(XMLPoolingDataSourceFactory.java:75)
    at org.apache.cayenne.configuration.server.DelegatingDataSourceFactory.getDataSource(DelegatingDataSourceFactory.java:68)
    at org.apache.cayenne.configuration.server.DefaultDataNodeFactory.createDataNode(DefaultDataNodeFactory.java:79)
    at org.apache.cayenne.configuration.server.DataDomainProvider.addDataNode(DataDomainProvider.java:175)
    at org.apache.cayenne.configuration.server.DataDomainProvider.createAndInitDataDomain(DataDomainProvider.java:127)
    at org.apache.cayenne.configuration.server.DataDomainProvider.get(DataDomainProvider.java:91)
    at org.apache.cayenne.configuration.server.DataDomainProvider.get(DataDomainProvider.java:56)
    at org.apache.cayenne.di.spi.CustomProvidersProvider.get(CustomProvidersProvider.java:39)
    at org.apache.cayenne.di.spi.FieldInjectingProvider.get(FieldInjectingProvider.java:43)
    at org.apache.cayenne.di.spi.DefaultScopeProvider.get(DefaultScopeProvider.java:50)
    at org.apache.cayenne.di.spi.DefaultInjector.getInstance(DefaultInjector.java:139)
    at org.apache.cayenne.di.spi.FieldInjectingProvider.value(FieldInjectingProvider.java:105)
    at org.apache.cayenne.di.spi.FieldInjectingProvider.injectMember(FieldInjectingProvider.java:68)
    at org.apache.cayenne.di.spi.FieldInjectingProvider.injectMembers(FieldInjectingProvider.java:59)
    at org.apache.cayenne.di.spi.FieldInjectingProvider.get(FieldInjectingProvider.java:44)
    at org.apache.cayenne.di.spi.DefaultScopeProvider.get(DefaultScopeProvider.java:50)
    at org.apache.cayenne.di.spi.DefaultInjector.getInstance(DefaultInjector.java:134)
    at org.apache.cayenne.configuration.CayenneRuntime.newContext(CayenneRuntime.java:124)
    at com.company.databases.postgresql.accountsdb.dataservices.AccountServices.loginAsEmailAddress(AccountServices.java:454)
    at com.company.databases.postgresql.accountsdb.dataservices.AccountServices.login(AccountServices.java:445)
    at com.company.actions.fan.account.AccountActions.login(AccountActions.java:44)
    at com.company.serverapps.fans.entrypoints.standard.AccountConnections.login(AccountConnections.java:95)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
    at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:160)
    at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
    at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
    at org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
    at org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:315)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:297)
    at org.glassfish.jersey.internal.Errors.process(Errors.java:267)
    at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
    at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
    at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
    at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
    at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
    at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:841)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1634)
    at org.eclipse.jetty.servlets.CrossOriginFilter.handle(CrossOriginFilter.java:308)
    at org.eclipse.jetty.servlets.CrossOriginFilter.doFilter(CrossOriginFilter.java:262)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1621)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:541)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1592)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:188)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1239)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:168)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:481)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1561)
    at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:166)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1141)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:213)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
    at org.eclipse.jetty.server.Server.handle(Server.java:564)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:320)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
    at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:279)
    at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:110)
    at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:124)
    at org.eclipse.jetty.util.thread.Invocable.invokePreferred(Invocable.java:122)
    at org.eclipse.jetty.util.thread.strategy.ExecutingExecutionStrategy.invoke(ExecutingExecutionStrategy.java:58)
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:201)
    at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:133)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:672)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:590)
    at java.lang.Thread.run(Thread.java:745)

Apr 03, 2017 10:21:58 PM org.postgresql.Driver connect
SEVERE: Connection error: 
org.postgresql.util.PSQLException: FATAL: sorry, too many clients already
    at org.postgresql.core.v3.ConnectionFactoryImpl.doAuthentication(ConnectionFactoryImpl.java:438)
    at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:222)
    at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:49)
    at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:194)
    at org.postgresql.Driver.makeConnection(Driver.java:431)
    at org.postgresql.Driver.connect(Driver.java:247)
    at org.apache.cayenne.datasource.DriverDataSource.getConnection(DriverDataSource.java:159)
    at org.apache.cayenne.datasource.DriverDataSource.getConnection(DriverDataSource.java:133)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.createUnwrapped(UnmanagedPoolingDataSource.java:300)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.createWrapped(UnmanagedPoolingDataSource.java:293)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.createUnchecked(UnmanagedPoolingDataSource.java:273)
    at org.apache.cayenne.datasource.UnmanagedPoolingDataSource.managePool(UnmanagedPoolingDataSource.java:188)
    at org.apache.cayenne.datasource.PoolingDataSourceManager.run(PoolingDataSourceManager.java:71)

例如：

public final static Long newFanAccount() {
        ServerRuntime accountsDBPostgresRuntime = AccountsDBRuntime.getAccountsDBPostgreSQLRuntime();
        ObjectContext context = accountsDBPostgresRuntime.newContext();
        Fan fan = context.newObject(Fan.class);
        context.commitChanges();
        Long fanID = (Long) Cayenne.pkForObject(fan);
        return fanID;
    }

---

从堆栈跟踪和代码示例来看，您似乎没有重用Cayenne堆栈（ServerRuntime对象），而是每次都创建一个新的堆栈。除了速度慢之外，这还会导致资源泄漏。每个ServerRuntime都有自己的连接池，您不会关闭它。因此，PostreSQL服务器迟早会因打开的连接而溢出

---

解决方案是将ServerRuntime转换为应用程序范围的单例（例如，使其成为AccountsDBRuntime的静态变量），并在需要新ObjectContext时重用它。

看起来Apache Cayenne不使用连接池或泄漏连接。如果您无法将其配置为使用更少的PostgreSQL连接，请使用pgBouncer之类的外部连接池。这有点奇怪，但我没有找到如何在Cayene中释放数据库连接。该错误清楚地表明资源过度使用正在发生，但您不能表示您已使用该特定资源（除非

commitChanges（）

是这样。）@ikevin8me，您的示例方法是否在调用

commit

之前抛出异常？如果是这样，请尝试将所有内容包装在

try

块中，如果捕获到任何内容，请执行

rollback

。@Laurenz这可能有意义，但我不确定。让我们等待更多答案。@Prokhorov否，commitChanges（）不会抛出任何错误，并且有许多成功的事务。错误发生在一些测试之后，比如超过30个成功的事务。我想让我们等待卡宴专家的回答。他们将确切地知道为什么以及如何防止这种情况。

public final static Long newFanAccount() {
        ServerRuntime accountsDBPostgresRuntime = AccountsDBRuntime.getAccountsDBPostgreSQLRuntime();
        ObjectContext context = accountsDBPostgresRuntime.newContext();
        Fan fan = context.newObject(Fan.class);
        context.commitChanges();
        Long fanID = (Long) Cayenne.pkForObject(fan);
        return fanID;
    }