11

I am trying to continuously send GET and POST requests to a REST API every few minutes. The issue is that after exactly 1000 requests I receive a GOAWAY frame (and an IOException):

The GOAWAY frame (type=0x7) is used to initiate shutdown of a connection or to signal serious error conditions.
HTTP/2 spec

I did a fair bit of research and found that not only is 1000 requests nginx's default maximum, Cloudfront (related Chromium issue) and Discord also exhibit the same behavior.

I tried to reproduce this problem with a local nginx server with the default HTTP/2 configuration:

server {
    listen 443 http2 ssl;
    http2_max_requests 1000;
    ...
}

var client = HttpClient.newBuilder()
        .version(HttpClient.Version.HTTP_2)
        .build();

for (var i = 0; i < 1100; i++) {
    var url = URI.create(String.format("https://localhost/images/test%d.jpg", i));

    var request = HttpRequest.newBuilder().uri(url).build();

    client.send(request, HttpResponse.BodyHandlers.discarding());
    System.out.printf("Image %d processed%n", i);
}

And after approximately 1000 requests, I get a GOAWAY error as expected:

...
Image 998 processed
Exception in thread "main" java.io.IOException: /127.0.0.1:49259: GOAWAY received

My first thought would be to check if the exception message contains the string "GOAWAY" and then retry the request accordingly:

try {
    client.send(request, HttpResponse.BodyHandlers.discarding());
} catch (IOException e) {
    if (e.getMessage().contains("GOAWAY")) {
        client.send(request, HttpResponse.BodyHandlers.discarding());
    } else throw e;
}

My issue with this approach is that the string comparison seems like it may be fragile. Additionally, since all I have is an IOException with a message, I can't differentiate between GOAWAY frames with a genuine error code (in which case I should probably stop sending requests) and those with NO_ERROR (in which case I could probably retry the request).

How should I correctly deal with/handle GOAWAY errors (apart from using HTTP/1.1 instead)?

4

1 回答 1

11

服务器有权随时以任何理由关闭连接。

在 HTTP/2GOAWAY帧中指示服务器处理的最后一个流是什么，因此客户端可以知道当连接关闭时需要重新发送什么流。

不幸的lastStreamId是，没有出现在 中java.net.http.HttpClient，因此无法知道它并采取适当的措施。

lastStreamId您的替代方法可能是GOAWAY使用其他支持显示lastStreamId.

[免责声明，我是 Jetty HTTP/2 实施者]
Jetty 支持较低级别的 HTTP/2 客户端，您可以将其用于您的用例 - 您可能想尝试一下。HTTP2Client 您可以在此处找到如何使用 Jetty 的示例。

于 2019-03-10T20:58:14.070 回答