HttpsServer导致curl造成100％的CPU负载 [英] HttpsServer causes 100% CPU load with curl

问题描述

我围绕Java的 HttpsServer 。

I've created a minimal application around Java's HttpsServer.

我已经安装了一个 HttpHandler 会以短文本消息回复请求：

I've installed an HttpHandler that replies to a request with a short text message:

return exchange -> {
    try {
        OutputStream responseBodyStream = exchange.getResponseBody();

        byte[] response = "Trouble with HTTPS and curl\n"
                .getBytes(StandardCharsets.UTF_8);

        exchange.getResponseHeaders().set("Content-Type", "text/plain");

        exchange.sendResponseHeaders(200, response.length);

        responseBodyStream.write(response);

        responseBodyStream.close();

        // Note that exchange.close() also closes the exchange's input stream
        // and output stream

    } catch (Exception e) {
        log.warn("Could not handle request", e);
    }
};

使用curl连接到服务器时，服务器会做出响应，但Java进程会继续使用整个内核，

When connecting to the server with curl, the server responds but the Java process keeps using an entire core, thus rendering the server unresponsive.

此行触发了该问题：

responseBodyStream.close();

如果我们删除该行，服务器将继续工作。

If we remove the line, the server keeps on working.

来自文档：

为了正确终止每次交换，输出即使未发送响应正文，流也必须关闭。

In order to correctly terminate each exchange, the output stream must be closed, even if no response body is being sent.

我已经创建了一个复制问题的项目。

I've created a project to reproduce the issue.

一些潜在的线索到目前为止，我发现：

Some potential clues I've found up till now:

• 仅当使用curl连接到服务器时，CPU使用率高。使用Firefox连接时，CPU使用率保持较低


• 使用不带TLS的常规HTTP服务器时，curl不会出现此问题


• 使用< a href = https://en.wikipedia.org/wiki/JDK_Flight_Recorder rel = nofollow noreferrer>飞行记录器表示其中的 SSLEngineImpl＃writeRecord 线程 HTTP-Dispatcher 分配很多对象

• High CPU usage only occurs when connecting to the server with curl. When connecting with Firefox, CPU usage stays low
• The issue does not occur with curl when using a regular HTTP server without TLS
• Data gathered using Flight Recorder indicate that SSLEngineImpl#writeRecord in the thread HTTP-Dispatcher allocates a lot of objects

我在使用OpenJDK 12.0.1 + 12的Arch Linux 5.1.7。 curl的版本是7.65.1。

I'm on Arch Linux 5.1.7 using OpenJDK 12.0.1+12. The version of curl is 7.65.1.

这是JDK中的错误吗？还是我以错误的方式使用 HttpsServer ？

Is this a bug in the JDK? Or am I using HttpsServer the wrong way?

推荐答案

我也可以重现此问题。

SSLStreams.doClosure 中有一个无限循环-这绝对是一个JDK错误。

I could also reproduce the problem.
There is an infinite loop in SSLStreams.doClosure - this is definitely a JDK bug.

HttpsServer在JDK 10中工作正常，但在JDK 11中开始循环。我想问题是HttpsServer实现尚未适应JDK 11中出现的TLS v1.3半关闭策略。

HttpsServer worked fine in JDK 10, but starts looping in JDK 11. I guess the problem is that HttpsServer implementation has not been adapted to TLS v1.3 half-close policy appeared in JDK 11.

幸运的是，有一种解决方法。添加 -Djdk.tls.acknowledgeCloseNotify = true JVM选项。使用此选项，HttpsServer将按预期工作。有关详细信息，请参见 JDK-8208526 。

Fortunately, there is a workaround. Add -Djdk.tls.acknowledgeCloseNotify=true JVM option. With this option HttpsServer will work as expected. See JDK-8208526 for details.

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