HttpURLConnection上的Tomcat内存泄漏警告

Question

Tomcat 8.5中有以下警告，我不确定是否可以忽略

WARNING [localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [AppName] appears to have started a thread named [pool-20-thread-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.net.SocketInputStream.socketRead0(Native Method)
java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
java.net.SocketInputStream.read(SocketInputStream.java:171)
java.net.SocketInputStream.read(SocketInputStream.java:141)
sun.security.ssl.InputRecord.readFully(InputRecord.java:465)
sun.security.ssl.InputRecord.read(InputRecord.java:503)
sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:983)
sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1385)
sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1413)
sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1397)
sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559)
sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)

它发生在以下代码中的connect：

URL url = new URL(MY_URL);
URLConnection con = url.openConnection();
HttpURLConnection http = (HttpURLConnection) con;
http.setRequestMethod("POST");
http.setDoOutput(true);
http.setFixedLengthStreamingMode(out.length);
http.setRequestProperty("Content-Type", "application/json");
http.connect();
try (OutputStream os = http.getOutputStream()) {
    os.write(out);
}

我是否应该在关闭输入流时添加一个finally：

http.getInputStream().close();

或者这段代码应该升级/转换为使用URIBuilder和HttpHost？

使用Spring的@Scheduled




Answer 1

您正在Tomcat中使用@Scheduled生成线程。您必须确保当ServletContext被破坏时，这些线程将完成，例如，战争被取消部署，Tomcat会警告您这一点。HTTP请求代码与此无关，因为URLConnection不会启动新线程来执行请求。

让Tomcat开心的一种方法是使用守护进程线程，如本文所述。这可以通过自定义taskSchedulerbean完成：

@Configuration
@EnableScheduling
public class TaskConfiguration {

  @Bean(destroyMethod = "shutdown")
  public Executor taskScheduler() {
    return Executors.Executors.newFixedThreadPool(4,
        new ThreadFactory() {
          public Thread newThread(Runnable r) {
            Thread t = Executors.defaultThreadFactory().newThread(r);
            t.setDaemon(true);
            return t;
          }
        });
  }

}