Rest Dropwizard:MaxQueuedRequests配置

我想将dropwizard传入的请求限制为3。 因此，如果服务器正在处理3个请求，我想发送一个503：“服务器容量已达到”响应代码

我知道Dropwizard具有最大排队请求数的配置：

MaxQueuedRequests

默认值为1024。 但是，我不知道如何使用这个参数。 当我做这个3，我的服务器不会启动

如果有人能提供更多信息，说明实现这一目标的首选设计模式是什么

我考虑的一种方法是：使用一个全局（或静态）变量来保持计数器。 对于每个请求，我都会增加计数器。 当计数器>3时，我用代码503响应

想听听更多关于这方面的想法吗

编辑：

所以我在@pandaadb-answer之后取得了进展。 然而，我遇到了另一个障碍：（ 这就是我的配置：

server:
   minThreads: 2
   maxQueuedRequests: 3
   type: simple
   applicationContextPath: /
   adminContextPath: /admin
   connector:
       type: http
       port: 9999

在这种情况下，我不断得到以下例外情况：

WARN  [2016-06-23 08:38:52,354] io.dropwizard.setup.AdminEnvironment: 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!    THIS APPLICATION HAS NO HEALTHCHECKS. THIS MEANS YOU WILL NEVER KNOW      !
!     IF IT DIES IN PRODUCTION, WHICH MEANS YOU WILL NEVER KNOW IF YOU'RE      !
!    LETTING YOUR USERS DOWN. YOU SHOULD ADD A HEALTHCHECK FOR EACH OF YOUR    !
!         APPLICATION'S DEPENDENCIES WHICH FULLY (BUT LIGHTLY) TESTS IT.       !
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
INFO  [2016-06-23 08:38:52,358] org.eclipse.jetty.server.handler.ContextHandler: Started i.d.j.MutableServletContextHandler@9d200de{/admin,null,AVAILABLE}
WARN  [2016-06-23 08:38:52,363] org.eclipse.jetty.util.thread.QueuedThreadPool: dw{STARTED,2<=3<=1024,i=0,q=3} rejected org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
WARN  [2016-06-23 08:38:52,367] org.eclipse.jetty.util.component.AbstractLifeCycle: FAILED org.eclipse.jetty.server.ServerConnector$ServerConnectorManager@289ba785: java.util.concurrent.RejectedExecutionException: org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
! java.util.concurrent.RejectedExecutionException: org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
! at org.eclipse.jetty.util.thread.QueuedThreadPool.execute(QueuedThreadPool.java:362) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.execute(SelectorManager.java:160) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.doStart(SelectorManager.java:258) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractConnector.doStart(AbstractConnector.java:256) [jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractNetworkConnector.doStart(AbstractNetworkConnector.java:81) [jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.ServerConnector.doStart(ServerConnector.java:236) [jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.Server.doStart(Server.java:366) [jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at io.dropwizard.cli.ServerCommand.run(ServerCommand.java:43) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:43) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:76) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.Cli.run(Cli.java:70) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.Application.run(Application.java:73) [dropwizard-core-0.8.2.jar:0.8.2]
! at net.lacework.eventgen.EventGeneratorMain.main(EventGeneratorMain.java:16) [classes/:na]
! at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_77]
! at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_77]
! at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_77]
! at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_77]
! at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]
WARN  [2016-06-23 08:38:52,368] org.eclipse.jetty.util.component.AbstractLifeCycle: FAILED query@3e8f7922{HTTP/1.1}{0.0.0.0:9999}: java.util.concurrent.RejectedExecutionException: org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
! java.util.concurrent.RejectedExecutionException: org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
! at org.eclipse.jetty.util.thread.QueuedThreadPool.execute(QueuedThreadPool.java:362) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.execute(SelectorManager.java:160) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.doStart(SelectorManager.java:258) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractConnector.doStart(AbstractConnector.java:256) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractNetworkConnector.doStart(AbstractNetworkConnector.java:81) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.ServerConnector.doStart(ServerConnector.java:236) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.Server.doStart(Server.java:366) [jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) [jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at io.dropwizard.cli.ServerCommand.run(ServerCommand.java:43) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:43) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:76) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.Cli.run(Cli.java:70) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.Application.run(Application.java:73) [dropwizard-core-0.8.2.jar:0.8.2]
! at net.lacework.eventgen.EventGeneratorMain.main(EventGeneratorMain.java:16) [classes/:na]
! at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_77]
! at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_77]
! at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_77]
! at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_77]
! at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]
WARN  [2016-06-23 08:38:52,368] org.eclipse.jetty.util.component.AbstractLifeCycle: FAILED org.eclipse.jetty.server.Server@70242f38: java.util.concurrent.RejectedExecutionException: org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
! java.util.concurrent.RejectedExecutionException: org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
! at org.eclipse.jetty.util.thread.QueuedThreadPool.execute(QueuedThreadPool.java:362) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.execute(SelectorManager.java:160) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.doStart(SelectorManager.java:258) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractConnector.doStart(AbstractConnector.java:256) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractNetworkConnector.doStart(AbstractNetworkConnector.java:81) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.ServerConnector.doStart(ServerConnector.java:236) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.Server.doStart(Server.java:366) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at io.dropwizard.cli.ServerCommand.run(ServerCommand.java:43) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:43) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:76) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.Cli.run(Cli.java:70) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.Application.run(Application.java:73) [dropwizard-core-0.8.2.jar:0.8.2]
! at net.lacework.eventgen.EventGeneratorMain.main(EventGeneratorMain.java:16) [classes/:na]
! at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_77]
! at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_77]
! at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_77]
! at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_77]
! at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]
ERROR [2016-06-23 08:38:52,368] io.dropwizard.cli.ServerCommand: Unable to start server, shutting down
! java.util.concurrent.RejectedExecutionException: org.eclipse.jetty.util.thread.NonBlockingThread@109d724c
! at org.eclipse.jetty.util.thread.QueuedThreadPool.execute(QueuedThreadPool.java:362) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.execute(SelectorManager.java:160) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.io.SelectorManager.doStart(SelectorManager.java:258) ~[jetty-io-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.start(ContainerLifeCycle.java:132) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.ContainerLifeCycle.doStart(ContainerLifeCycle.java:106) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractConnector.doStart(AbstractConnector.java:256) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.AbstractNetworkConnector.doStart(AbstractNetworkConnector.java:81) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.ServerConnector.doStart(ServerConnector.java:236) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.server.Server.doStart(Server.java:366) ~[jetty-server-9.2.9.v20150224.jar:9.2.9.v20150224]
! at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:68) ~[jetty-util-9.2.9.v20150224.jar:9.2.9.v20150224]
! at io.dropwizard.cli.ServerCommand.run(ServerCommand.java:43) ~[dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.EnvironmentCommand.run(EnvironmentCommand.java:43) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.ConfiguredCommand.run(ConfiguredCommand.java:76) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.cli.Cli.run(Cli.java:70) [dropwizard-core-0.8.2.jar:0.8.2]
! at io.dropwizard.Application.run(Application.java:73) [dropwizard-core-0.8.2.jar:0.8.2]

WARN[2016-06-23 08:38:52354]io.dropwizard.setup.AdminEnvironment:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
！此应用程序没有健康检查。这意味着您永远不会知道！
！如果它在生产过程中死亡，这意味着你永远不会知道自己是否死亡！
！让您的用户失望。您应该为每个用户添加一个健康检查！
！应用程序的依赖项，它完全（但很容易）测试它！
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
信息[2016-06-23 08:38:52358]org.eclipse.jetty.server.handler.ContextHandler:Started i.d.j。MutableServletContextHandler@9d200de{/admin，空，可用}
WARN[2016-06-23 08:38:52363]org.eclipse.jetty.util.thread.QueuedThreadPool:dw{STARTED，2我认为您的问题是您只更改了一个值，而没有更改其他值。dw验证无法处理这种情况

如果不同时更改容量，则设置MaxQueuedRequests不允许3。请查看此处：

/**
     * Create a bounded {@link BlockingArrayQueue} that grows by the given parameter.
     * 
     * @param capacity
     *            the initial capacity
     * @param growBy
     *            the growth factor
     * @param maxCapacity
     *            the maximum capacity
     */
    public BlockingArrayQueue(int capacity, int growBy, int maxCapacity)
    {
        if (capacity > maxCapacity)
            throw new IllegalArgumentException();
        _elements = new Object[capacity];
        _growCapacity = growBy;
        _maxCapacity = maxCapacity;
    }

这由服务器工厂调用：

protected ThreadPool createThreadPool(MetricRegistry metricRegistry) {
        final BlockingQueue<Runnable> queue = new BlockingArrayQueue<>(minThreads, maxThreads, maxQueuedRequests);
        final InstrumentedQueuedThreadPool threadPool =
                new InstrumentedQueuedThreadPool(metricRegistry, maxThreads, minThreads,
                                                 (int) idleThreadTimeout.toMilliseconds(), queue);
        threadPool.setName("dw");
        return threadPool;
    }

你的错误并不是一个真正的错误——我相信这是Jetty中的一个bug（或者更确切地说是一个在启动时没有验证的错误配置）

问题是jetty启动了一些acceptorthreads/selectorthreads。这些是count（）>3。但是线程是由服务器生命周期启动的，因此jetty将它们轰炸到自己的线程池中。这没有问题，因为它们一旦执行就会消失（您可以通过设置断点并缓慢启动来测试这一点-您的服务器将正常启动）

解决方案是限制接受器/选择器线程（请进行一些实验/研究，以了解它们的作用，并正确配置它们）。
因此，通过限制这些线程，启动不会使jetty过载，并且一切都可以正常启动

（我没有用这个相当奇怪的设置做任何关于性能/稳定性的实验）

FWIW-我解决这个问题的方法：

实现对传入/传出请求进行计数的请求筛选器。一旦传入请求且计数器>X，立即拒绝请求，并给出指示高负载的响应，然后重试（以便您的客户端知道该怎么做）。上面的配置可能会导致jetty抛出500个，这会使您的客户端认为您的服务器已关闭

问候,

Artur
您有什么例外？请发布您的yaml配置。谢谢@pandaadb。我正在更新我的问题，并提供更多错误详细信息。
server:
  minThreads: 2
  maxQueuedRequests: 3
  rootPath: /api/*
  requestLog:
    appenders: []
  applicationConnectors:
  - type: http
    port: 9085
    acceptorThreads: 3
    selectorThreads: 3