Java: HTTP连接创建的等待连接线程的活动时间很长

Question

我有一个服务器端代码，它检查SOAP服务是否运行。代码看起来如下：

String response = "";

while (response.length() == 0) {
    try {
        final URL url = new URL("DummySoapServiceURL");
        final HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection();
        InputStream inputStream = null;
        try {
            httpConnection.setRequestMethod("GET");

            inputStream = httpConnection.getInputStream();
            final byte[] buffer = new byte[BUFFER_SIZE];
            while (inputStream.read(buffer, 0, BUFFER_SIZE) != -1) {
                response = new String(buffer);
            }
        } finally {
            IOUtils.closeQuietly(inputStream);
            httpConnection.disconnect();
        }
    } catch (MalformedURLException e) {
        // error handling
    } catch (IOException e) {
        // error handling
    }
}

现在的问题是，每检查3-4个连接线程都会被创建。即使SOAP服务检查已经完成，这些线程仍然是活动的。线程转储的快照，这些线程如下所示：

"http-host/ip:port-11" prio=10 tid=0x00000000064f0000 nid=0x32cc waiting on condition [0x00002b54bc604000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000d5093c78> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
    at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at org.apache.tomcat.util.net.NioEndpoint$DefaultThreadFactory$1$1.run(NioEndpoint.java:1249)
    at java.lang.Thread.run(Thread.java:744)
   Locked ownable synchronizers:
    - None

现在我不知道为什么这些连接线程在等待/停车，以及如何关闭它们。在我的代码中，打开的流被关闭，连接被断开。

我还尝试设置以下HTTP属性：

httpConnection.addRequestProperty("Connection", "close");

但没什么用。我怀疑JAVA可能会在某个时候关闭这些线程。但我不知道，什么时候，怎么做？JDK版本是jdk1.7.0_51_x64。请告诉我，如何阻止这些连接线程号的建立？

Answer 1

迁移了整个实现，以使用apache客户端，因为它具有更好控制的特殊API。但没什么用。即使使用apache客户端，我也可以看到这些等待的连接线程。

终于在用于JBOSS连接器配置的redhat网站上找到了提示。为HTTP连接器配置了线程池，并解决了这个问题：

<subsystem xmlns="urn:jboss:domain:threads:1.1"> 
    <thread-factory name="http-connector-factory" group-name="uq-thread-pool" thread-name-pattern="HTTP-%t" priority="9"/> 
    <unbounded-queue-thread-pool name="uq-thread-pool"> 
        <max-threads count="5"/> 
        <keepalive-time time="5" unit="seconds"/> 
        <thread-factory name="http-connector-factory"/> 
    </unbounded-queue-thread-pool> 
</subsystem> 

<subsystem xmlns="urn:jboss:domain:web:2.2" default-virtual-server="default-host" native="false">

    <connector name="http" protocol="org.apache.coyote.http11.Http11NioProtocol" scheme="http" socket-binding="http" executor="uq-thread-pool"/> 
    ....
    ....