在Glassfish v3中，没有明显原因依次执行Servlet请求 [英] Servlet requests are executed sequentially for no apparent reason in Glassfish v3

问题描述

我正在使用Glassfish 3 Web配置文件，无法让http worker在servlet上执行并发请求。

I'm using Glassfish 3 Web profile and can't get http workers to execute concurrently requests on a servlet.

这就是我观察问题的方法。我做了一个非常简单的servlet，它将当前线程名称写入标准输出并休眠10秒：

This is how i observed the problem. I've made a very simple servlet, that writes the current thread name to the standard output and sleep for 10 seconds :

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    System.out.println(Thread.currentThread().getName());
    try {
        Thread.sleep(10000); // 10 sec
    }
    catch (InterruptedException ex) {
    }
}

当我同时运行多个请求时，我清楚地在日志中看到请求是按顺序执行的（每10秒一个跟踪）。

And when i'm running several simultaneous requests, I clearly see in the logs that the requests are sequentially executed (one trace every 10 seconds).

INFO: http-thread-pool-8080-(2)
(10 seconds later...)
INFO: http-thread-pool-8080-(1)
(10 seconds later...)
INFO: http-thread-pool-8080-(2)

等。

我所有的GF设置都不受影响 - 这是开箱即用的配置（默认线程池最少2个线程，如果我没记错的话，最多5个）。

All my GF settings are untouched - it's the out-of-the-box config (the default thread pool is 2 threads min, 5 max if I recall properly).

我真的不明白为什么睡觉（）阻止所有其他工作线程。非常感谢任何见解！

I really don't understand why the sleep() block all the others worker threads. Any insight would be greatly appreciated !

推荐答案

克里斯在评论中将其钉死了。我复制了你的servlet，按如下方式测试：

Chris nailed it down in his comment. I copied your servlet, tested it as follows:

package com.stackoverflow.q2755338;

import java.io.IOException;
import java.net.URL;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Test {

    public static void main(String... args) throws Exception {
        // Those are indeed called sequentially.
        System.out.println("Starting to fire 3 requests in current thread...");
        new TestURL().run();
        new TestURL().run();
        new TestURL().run();
        System.out.println("Finished firing 3 requests in current thread!");

        // But those are called three at once.
        System.out.println("Starting to fire 3 requests in each its own thread...");
        ExecutorService executor = Executors.newFixedThreadPool(3);
        executor.submit(new TestURL());
        executor.submit(new TestURL());
        executor.submit(new TestURL());
        System.out.println("Finished firing 3 requests in each its own thread!");
        executor.shutdown();
    }

}

class TestURL implements Runnable {

    @Override
    public void run() {
        try {
            System.out.println("Firing request...");
            new URL("http://localhost:8181/JavaEE6/test").openStream();
            System.out.println("Request finished!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

服务器端的结果是：

INFO: start: http-thread-pool-8181-(2)
(10 seconds)
INFO: end: http-thread-pool-8181-(2)
INFO: start: http-thread-pool-8181-(1)
(10 seconds)
INFO: end: http-thread-pool-8181-(1)
INFO: start: http-thread-pool-8181-(2)
(10 seconds)
INFO: end: http-thread-pool-8181-(2)

INFO: start: http-thread-pool-8181-(1)
INFO: start: http-thread-pool-8181-(2)
INFO: start: http-thread-pool-8181-(3)
(10 seconds)
INFO: end: http-thread-pool-8181-(1)
INFO: end: http-thread-pool-8181-(2)
INFO: end: http-thread-pool-8181-(3)

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