请求重试之间超时Apache HttpClient

关于动态延迟,我想建议如下:

CloseableHttpClient client = HttpClientBuilder.create()
    .setRetryHandler(new HttpRequestRetryHandler() {
        @Override
        public boolean retryRequest(IOException exception, int executionCount, HttpContext context) {
            return executionCount <= maxRetries ;
        }
    })
    .setServiceUnavailableRetryStrategy(new ServiceUnavailableRetryStrategy() {
        int waitPeriod = 100;
        @Override
        public boolean retryRequest(HttpResponse response, int executionCount, HttpContext context) {
            waitPeriod *= 2;
            return executionCount <= maxRetries &&
               response.getStatusLine().getStatusCode() >= 500; //important!
        }

        @Override
        public long getRetryInterval() {
            return waitPeriod;
        }
    })
    .build();

附件: 请注意,ServiceUnavailableRetryStrategy。如果出现超时、端口未打开或连接关闭等IO错误,则不会调用retryRequest。在这种情况下,只有HttpRequestRetryHandler。将调用retryRequest,重试将立即发生或在固定延迟后发生(我无法最终澄清这一点)。所以奥列格的答案实际上是正确的。有了HttpClient 4.5的支持,就无法做到这一点。

(实际上,我想把这称为设计错误,因为IO错误后延迟重试在现代微服务环境中至关重要。)

BackoffManager / ConnectionBackoffStrategy combo可用于根据输入/输出错误率和503响应动态增加或减少每条路由的最大连接限制。它们对请求执行没有影响,不能用于控制请求重新执行

这是HC 4所能做到的最好的。x API

CloseableHttpClient client = HttpClientBuilder.create()
        .setRetryHandler(new HttpRequestRetryHandler() {
            @Override
            public boolean retryRequest(IOException exception, int executionCount, HttpContext context) {
                return executionCount <= maxRetries &&
                        exception instanceof SocketException;
            }
        })
        .setServiceUnavailableRetryStrategy(new ServiceUnavailableRetryStrategy() {
            @Override
            public boolean retryRequest(HttpResponse response, int executionCount, HttpContext context) {
                return executionCount <= maxRetries &&
                        response.getStatusLine().getStatusCode() == HttpStatus.SC_SERVICE_UNAVAILABLE;
            }

            @Override
            public long getRetryInterval() {
                return 100;
            }
        })
        .build();

请注意,在发生I/O错误的情况下,目前没有一种优雅的方法来强制执行请求执行尝试之间的延迟,或者根据请求路由动态调整重试间隔。

您可以使用lambda

client.setRetryHandler((e, execCount, httpContext) -> {
                if (execCount > tries) {
                    return false;
                } else {
                    try {
                        Thread.sleep(recalMillis);
                    } catch (InterruptedException ex) {
                        //ignore
                    }
                    return true;
                }

请注意,处理程序仅适用于IOExceptions类型