Java 11 HttpClient - HttpClient 与并发 HttpRequest 的最佳比率是多少

Question

在下面的示例中，我创建了一个 Java 11 httpClient，然后创建了多个并发 HttpRequest。

这是不好的做法吗？

每个 HttpRequest 都应该有自己的 HttpClient 吗？

HttpClient 可以拥有的 HttpRequest 数量是否有上限？

代码

    private static void httpClientExample(){
    
    HttpClient httpClient = HttpClient.newHttpClient();

    System.out.println("TP1");

    var task1 = httpClient.sendAsync(HttpRequest.newBuilder()
            .uri(URI.create("https://www.bing.com/"))
            .build(), HttpResponse.BodyHandlers.ofString())
            .thenApply(HttpResponse::uri).thenAccept(System.out::println);

    var task2 = httpClient.sendAsync(HttpRequest.newBuilder()
            .uri(URI.create("https://openjdk.java.net/"))
            .build(), HttpResponse.BodyHandlers.ofString())
            .thenApply(HttpResponse::uri).thenAccept(System.out::println);
    
    var task3 = httpClient.sendAsync(HttpRequest.newBuilder()
            .uri(URI.create("https://www.google.co.uk/"))
            .build(), HttpResponse.BodyHandlers.ofString())
            .thenApply(HttpResponse::uri).thenAccept(System.out::println);


    System.out.println("Requests Sent");

    try {
        Thread.sleep(5000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }

    System.out.println("Main Thread Completed");
    }

Answer 1

这在 API docs of HttpClient 中没有明确记录。 .但预计 HttpClient 旨在处理多个请求。这在某种意义上暗示于 Introduction to the Java HTTP Client :

Once built, an HttpClient can be used to send multiple requests.

现在，您的问题可能与管理客户端的并发性有关。而不是使用 HttpClient 的相同实例，这与它使用的执行程序服务有很大关系，这是您可以自定义的(请参阅 here ):

ExecutorService executorService = Executors.newFixedThreadPool(10);
HttpClient httpClient  = HttpClient.newBuilder()
                               .executor(executorService)
                               ... //more config
                               .build();

通过这种方式，您可以管理客户端用于运行异步请求的线程池。
换句话说:

Is this bad practice?

不

Should each HttpRequest have its own HttpClient?

不

Is there an upper limit on the number of HttpRequests a HttpClient can have?

您必须测试应用程序的最佳并发设置，然后使用相应配置的执行程序服务。