ExecutorService executor = Executors.newFixedThreadPool(poolSize); ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(poolSize); executor.setMaximumPoolSize(maxPoolSize); executor.setCorePoolSize(corePoolSize); executor.setKeepAliveTime(keepAliveTime, TimeUnit.SECONDS); ExecutorService executor = Executors.newFixedThreadPool(poolSize); HttpClient httpClient = HttpClient.newBuilder() .executor(executor) .build(); HttpRequest request1 = HttpRequest.newBuilder() .uri(URI.create("http://www.example.com")) .build(); HttpRequest request2 = HttpRequest.newBuilder() .uri(URI.create("http://www.example.com")) .build(); CompletableFuture<HttpResponse<String>> response1 = httpClient.sendAsync(request1, HttpResponse.BodyHandlers.ofString()); CompletableFuture<HttpResponse<String>> response2 = httpClient.sendAsync(request2, HttpResponse.BodyHandlers.ofString());