I have made the simplest com.sun.net.httpserver.HttpServer below. What I don’t understand is why server.setExecutor(mainExecutorGood) works (when you to localhost:8080/test you get a response) but if you server.setExecutor(mainExecutorBad) doesn’t work (when you go to localhost:8080/test the browser hangs).

The full class is below.

package xxx;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.logging.log4j.LogManager;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

public class ServerTest {


    @SuppressWarnings("restriction")
    public static HttpHandler testHandler() {
        return new HttpHandler() {
            @Override
            public void handle(HttpExchange httpExchange) throws IOException {
                // TODO Auto-generated method stub
                try {
                    String rt = "Test OK";
                    byte response[] = rt.getBytes("UTF-8");
                    httpExchange.getResponseHeaders().add("Content-Type", "text/plain; charset=UTF-8");
                    httpExchange.sendResponseHeaders(200, response.length);
                    OutputStream out = httpExchange.getResponseBody();
                    out.write(response);
                    out.close();
                } catch (IOException ucx) {
                    LogManager.getLogger().catching(ucx);
                    throw new RuntimeException(ucx);
                }
                
            }
            
        };
    }
    
    @SuppressWarnings("restriction")
    public static void main(String args[]) {
        int port = 8080;

        try {
            HttpServer server = HttpServer.create(new InetSocketAddress(port), 0);

            ThreadFactory tf = new ThreadFactory() {
                final AtomicInteger id = new AtomicInteger();
                @Override
                public Thread newThread(Runnable r) {
                    Thread t = new Thread();
                    int tid = id.getAndIncrement();
                    t.setName("http_server_worker_thread_" + tid);
                    return t;
                }
            };

            
            Executor mainExecutorBad = Executors.newCachedThreadPool(tf);
            Executor mainExecutorGood = Executors.newCachedThreadPool();
            server.setExecutor(mainExecutorGood);


            server.createContext("/test", testHandler());

            Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
            Thread.currentThread().setName("main_thread");
            server.start();

        } catch (Throwable tr) {
            System.err.println("throwable problem");
        }
    }

}