线程挂起时使用java.net.HttpURLConnection'；这是一个自https连接

我目前正在编写一个API，它需要从服务器A到自身建立HTTPS连接。使用Jmeter进行测试，我发现线程很容易挂起，甚至10个线程同时启动。但是，如果连接到其他服务器，则问题不存在。我只用了几行代码来测试它。它提出了同样的问题

try {
        URL url = new URL("some URL that connects to the server itself");
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.setConnectTimeout(20000);
        con.setReadTimeout(30000);
        con.setRequestMethod("GET");
        con.setDoInput(true);
        BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String line = reader.readLine();
        int count = 0;
        while (line != null) {
            count += line.length();
           line = reader.readLine();
        }
        //con.disconnect();
      }catch(Exception e){
          e.printStackTrace();
      }

在10个线程中，只有2个线程返回了预期的结果，其他线程似乎都因堆栈跟踪而超时

[err] java.net.SocketTimeoutException: Read timed out
[err]     at java.net.SocketInputStream.socketRead0(Native Method)
[err]     at java.net.SocketInputStream.read(SocketInputStream.java:150)
[err]     at java.net.SocketInputStream.read(SocketInputStream.java:121)
[err]     at sun.security.ssl.InputRecord.readFully(InputRecord.java:465)
[err]     at sun.security.ssl.InputRecord.read(InputRecord.java:503)
[err]     at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:954)
[err]     at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1343)
[err]     at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1371)
[err]     at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1355)
[err]     at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:563)
[err]     at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
[err]     at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1511)
[err]     at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1439)
[err]     at com.sun.net.ssl.internal.www.protocol.https.HttpsURLConnectionOldImpl.getInputStream(HttpsURLConnectionOldImpl.java:224)

我使用-Djavax.net.debug=all启用调试选项，下面是控制台上显示的一些跟踪

Default Executor-thread-15, called closeInbound()
Default Executor-thread-15, fatal error: 80: Inbound closed before receiving peer's close_notify: possible truncation attack?
javax.net.ssl.SSLException: Inbound closed before receiving peer's close_notify: possible truncation attack?
%% Invalidated:  [Session-19, TLS_RSA_WITH_AES_128_CBC_SHA256]
Default Executor-thread-15
, SEND TLSv1.2 ALERT:
fatal,
description = internal_error
Default Executor-thread-15, Exception sending alert: java.io.IOException: writer side was already closed.

我的问题是，为什么连接到服务器本身时会出现问题？为什么每次只有两个连接返回？我该如何解决它？ 我尝试使用将

http.maxConnections

设置为系统属性

---

System.setProperty（“http.maxConnections”，String.valueOf（300））但没有帮助。
可能会显示服务器端代码。还有为什么断开连接被注释掉了？这是我用来测试问题的大部分服务器端代码。我对此进行了注释，因为一旦我将Keep-Alive设置为与con.setRequestProperty的连接（“Keep-Alive”，“300”）；con.setRequestProperty（“连接”、“保持活动”）；如果我在连接上调用disconnect（），保持活动状态将不会生效，对吗？不管怎么说，我打电话给disconnect也没用。