Internal feature toggle to disable virtual threads (#521)

* toggle to swap between virtual and physical threads

* creating system property

src/main/java/com/mageddo/dnsproxyserver/solver/RemoteResolvers.java

@@ -1,11 +1,11 @@
 package com.mageddo.dnsproxyserver.solver;
 
 import com.mageddo.net.IpAddr;
+import com.mageddo.utils.Executors;
 
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.function.Function;
 
 public class RemoteResolvers implements AutoCloseable {
@@ -23,7 +23,7 @@ public static RemoteResolvers of(List<IpAddr> servers, final Function<IpAddr, Re
       .stream()
       .map(resolverProvider)
       .toList();
-    return new RemoteResolvers(resolvers, Executors.newVirtualThreadPerTaskExecutor());
+    return new RemoteResolvers(resolvers, Executors.newThreadExecutor());
   }
 
   public List<Resolver> resolvers() {

src/main/java/com/mageddo/dnsserver/TCPServer.java

@@ -3,6 +3,7 @@
 import com.mageddo.commons.concurrent.ThreadPool;
 import com.mageddo.commons.io.IoUtils;
 import com.mageddo.dnsproxyserver.utils.Ips;
+import com.mageddo.utils.Executors;
 import lombok.extern.slf4j.Slf4j;
 import org.slf4j.MDC;
 
@@ -16,7 +17,6 @@
 import java.util.LinkedHashSet;
 import java.util.Set;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
@@ -36,7 +36,7 @@ public class TCPServer implements AutoCloseable {
 
   @Inject
   public TCPServer() {
-    this.serverThreadPool = Executors.newVirtualThreadPerTaskExecutor();
+    this.serverThreadPool = Executors.newThreadExecutor();
     this.clients = new LinkedHashSet<>();
   }
 

src/main/java/com/mageddo/dnsserver/UDPServer.java

@@ -2,14 +2,14 @@
 
 import com.mageddo.commons.io.IoUtils;
 import com.mageddo.dns.utils.Messages;
+import com.mageddo.utils.Executors;
 import lombok.extern.slf4j.Slf4j;
 import org.xbill.DNS.Message;
 
 import java.net.DatagramPacket;
 import java.net.DatagramSocket;
 import java.net.SocketAddress;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 
 @Slf4j
 public class UDPServer {
@@ -24,7 +24,7 @@ public class UDPServer {
   public UDPServer(SocketAddress address, RequestHandler requestHandler) {
     this.address = address;
     this.requestHandler = requestHandler;
-    this.pool = Executors.newVirtualThreadPerTaskExecutor();
+    this.pool = Executors.newThreadExecutor();
   }
 
   public void start() {

src/main/java/com/mageddo/net/NetExecutorWatchdog.java

@@ -3,21 +3,21 @@
 import com.mageddo.commons.circuitbreaker.CircuitCheckException;
 import com.mageddo.commons.concurrent.Threads;
 import com.mageddo.dnsproxyserver.utils.InetAddresses;
+import com.mageddo.utils.Executors;
 import lombok.extern.slf4j.Slf4j;
 
 import java.net.InetSocketAddress;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 
 @Slf4j
 public class NetExecutorWatchdog implements AutoCloseable {
 
   public static final int FPS_120 = 1000 / 120;
 
-  private final ExecutorService threadPool = Executors.newVirtualThreadPerTaskExecutor();
+  private final ExecutorService threadPool = Executors.newThreadExecutor();
 
   /**
    * Will ping the #pingAddr while waiting the future to be done, which occurs first will return,

src/main/java/com/mageddo/utils/Executors.java

@@ -0,0 +1,14 @@
+package com.mageddo.utils;
+
+import com.mageddo.commons.concurrent.ThreadPool;
+
+import java.util.concurrent.ExecutorService;
+
+public class Executors {
+  public static ExecutorService newThreadExecutor() {
+    if (Boolean.getBoolean("mg.physical_threads.active")) {
+      return ThreadPool.newFixed(50);
+    }
+    return java.util.concurrent.Executors.newVirtualThreadPerTaskExecutor();
+  }
+}

src/test/java/com/mageddo/dnsproxyserver/solver/SolverRemoteTest.java

@@ -1,6 +1,7 @@
 package com.mageddo.dnsproxyserver.solver;
 
 import com.mageddo.dnsproxyserver.solver.remote.application.CircuitBreakerNonResilientService;
+import com.mageddo.utils.Executors;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -16,7 +17,6 @@
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Executor;
-import java.util.concurrent.Executors;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
@@ -45,7 +45,7 @@ class SolverRemoteTest {
 
   @BeforeEach
   void beforeEach (){
-    doReturn(Executors.newVirtualThreadPerTaskExecutor())
+    doReturn(Executors.newThreadExecutor())
       .when(this.resolvers)
       .getExecutor();
   }

src/test/java/com/mageddo/utils/ExecutorsTest.java

@@ -0,0 +1,23 @@
+package com.mageddo.utils;
+
+import lombok.SneakyThrows;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class ExecutorsTest {
+
+  @Test
+  @SneakyThrows
+  void virtualThreadsActiveByDefault() {
+    // arrange
+    try (final var executor = Executors.newThreadExecutor()) {
+      // act
+      final var isVirtual = executor.submit(() -> Thread.currentThread().isVirtual()).get();
+
+      // assert
+      assertTrue(isVirtual);
+    }
+
+  }
+}