Java 11: implementing Multiple Concurrent HTTP Requests Using Apache HttpClient and Connection Pooling
Hey everyone, I'm running into an issue that's driving me crazy. I'm working with a question with making multiple concurrent HTTP requests using Apache HttpClient in Java 11. I have implemented a simple HTTP client that utilizes connection pooling, but I am getting a `java.net.ConnectException: Connection timed out` behavior intermittently when I exceed a certain number of simultaneous requests. Here’s a snippet of my code: ```java import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.impl.conn.PoolingHttpClientConnectionManager; public class HttpClientExample { private static final String URL = "http://example.com"; private static final int MAX_TOTAL_CONNECTIONS = 100; private static final int MAX_CONNECTIONS_PER_ROUTE = 20; public static void main(String[] args) throws InterruptedException { PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(); connectionManager.setMaxTotal(MAX_TOTAL_CONNECTIONS); connectionManager.setDefaultMaxPerRoute(MAX_CONNECTIONS_PER_ROUTE); try (CloseableHttpClient httpClient = HttpClients.custom() .setConnectionManager(connectionManager) .build()) { Runnable task = () -> { try { HttpGet request = new HttpGet(URL); HttpResponse response = httpClient.execute(request); System.out.println("Response Code: " + response.getStatusLine().getStatusCode()); } catch (IOException e) { e.printStackTrace(); } }; // Create and start multiple threads for (int i = 0; i < 50; i++) { new Thread(task).start(); } } } } ``` When I run this code, it works fine for a small number of threads, but when I scale it up to 50 or more, I start seeing timeouts. The server I’m connecting to is capable of handling the load, as I've tested it using a load testing tool with a higher number of requests. I've tried increasing the connection pool settings and even added some delays between request initiations, but the scenario continues. Here’s the relevant output when the timeout occurs: ``` java.net.ConnectException: Connection timed out: connect ``` I’m also monitoring the server-side logs and not seeing any indications of connection issues. Is there a known limitation with Apache HttpClient regarding concurrent requests, or is there a different approach I should consider? Any help would be appreciated!