HttpClient内存管理

Question

我有一个应用程序,它有一个线程池(ThreadPoolExecutor),它是每个执行HttpGet操作的传递任务,并将InputStream读入byte []以执行某些操作.

在阅读了HttpClient文档后,我得出的结论是,跨多个线程管理HttpClient连接的最佳方法是创建一个ThreadSafeClientConnManager并在整个应用程序中共享它.

实现这一点之后,我注意到即使在完成所有任务之后,仍然有大量内存仍由ThreadSafeClientConnManager使用.

查看堆转储,此内存采用byte []数组的形式.这些不是我创建的任何引用.它们由ThreadSafeClientConnManager及其池的各个部分保存.我不确定它们是否与InputStream相关或者它们是否是其他内容.

所有任务本身及其变量都被成功地垃圾收集.

如果我在ThreadSafeClientConnManager上调用getConnectionManager().shutdown(),则释放所有内存就好了.但是,我不想关闭连接,因为这些HttpGet任务可能随时发生.我希望在应用程序生命期间保持打开状态.

随着HttpGet任务的运行,持有的内存越来越多,最终可能导致内存不足错误.任务完成后,内存不会被释放.

在完成使用它的任务后,如何确保释放内存？

这是我正在使用的代码.它与HttpClient文档中的代码拼凑在一起,其他问题在SO和在线上.

HttpClient的创建:

// Create and initialize HTTP parameters
HttpParams params = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(params, 40 * 1000);
HttpConnectionParams.setSoTimeout(params, 40 * 1000);
ConnManagerParams.setMaxTotalConnections(params, 100);
HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);

// Create and initialize scheme registry 
SchemeRegistry schemeRegistry = new SchemeRegistry();
schemeRegistry.register( new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
schemeRegistry.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443));

// Create an HttpClient with the ThreadSafeClientConnManager.
// This connection manager must be used if more than one thread will
// be using the HttpClient.
ClientConnectionManager cm = new ThreadSafeClientConnManager(params, schemeRegistry);
mHttpClient = new DefaultHttpClient(cm, params);

然后,执行HTTPGET了Runnable是非常准确地从该例如基于HttpClient的实例为手动连接释放.以下是它的外观示例:

HttpClient httpclient = getTheSharedThreadSafeClientConnManager(); // Would return the mHttpClient from above
    try {
        HttpGet httpget = new HttpGet("http://www.apache.org/");

        // Execute HTTP request
        System.out.println("executing request " + httpget.getURI());
        HttpResponse response = httpclient.execute(httpget);

        System.out.println("----------------------------------------");
        System.out.println(response.getStatusLine());
        System.out.println("----------------------------------------");

        // Get hold of the response entity
        HttpEntity entity = response.getEntity();

        // If the response does not enclose an entity, there is no need
        // to bother about connection release
        if (entity != null) {
            InputStream instream = entity.getContent();
            try {
                instream.read();
                // do something useful with the response
            } catch (IOException ex) {
                // In case of an IOException the connection will be released
                // back to the connection manager automatically
                throw ex;
            } catch (RuntimeException ex) {
                // In case of an unexpected exception you may want to abort
                // the HTTP request in order to shut down the underlying
                // connection immediately.
                httpget.abort();
                throw ex;
            } finally {
                // Closing the input stream will trigger connection release
                try { instream.close(); } catch (Exception ignore) {}
            }
        }

    }

是否需要做更多的事情来释放每项任务的资源？我在他们的ThreadSafeClientConnManager示例中看到他们使用了HttpContext,但我找不到任何关于如何使用它的文档.这需要吗？如果是这样,你如何使用ThreadPoolExecutor？

非常感谢.

Answer 1

您是否曾调用ClientConnectionManager的releaseConnection(...)或closeExpiredConnections()方法？

Answer 2

在finally块中添加对HttpEntity.consumeContent()的调用