[grid] Add event bus heartbeat to prevent steal connection

java/src/org/openqa/selenium/events/zeromq/BoundZmqEventBus.java

@@ -20,6 +20,7 @@
 import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
+import java.time.Duration;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.logging.Level;
@@ -43,7 +44,11 @@ class BoundZmqEventBus implements EventBus {
   private final ExecutorService executor;
 
   BoundZmqEventBus(
-      ZContext context, String publishConnection, String subscribeConnection, Secret secret) {
+      ZContext context,
+      String publishConnection,
+      String subscribeConnection,
+      Secret secret,
+      Duration heartbeatPeriod) {
     String address = new NetworkUtils().getHostAddress();
     Addresses xpubAddr = deriveAddresses(address, publishConnection);
     Addresses xsubAddr = deriveAddresses(address, subscribeConnection);
@@ -53,11 +58,13 @@ class BoundZmqEventBus implements EventBus {
     xpub = context.createSocket(SocketType.XPUB);
     xpub.setIPv6(xpubAddr.isIPv6);
     xpub.setImmediate(true);
+    ZmqUtils.configureHeartbeat(xpub, heartbeatPeriod, "XPUB");
     xpub.bind(xpubAddr.bindTo);
 
     xsub = context.createSocket(SocketType.XSUB);
     xsub.setIPv6(xsubAddr.isIPv6);
     xsub.setImmediate(true);
+    ZmqUtils.configureHeartbeat(xsub, heartbeatPeriod, "XSUB");
     xsub.bind(xsubAddr.bindTo);
 
     executor =
@@ -68,8 +75,9 @@ class BoundZmqEventBus implements EventBus {
               return thread;
             });
     executor.submit(() -> ZMQ.proxy(xsub, xpub, null));
-
-    delegate = new UnboundZmqEventBus(context, xpubAddr.advertise, xsubAddr.advertise, secret);
+    delegate =
+        new UnboundZmqEventBus(
+            context, xpubAddr.advertise, xsubAddr.advertise, secret, heartbeatPeriod);
   }
 
   @Override

java/src/org/openqa/selenium/events/zeromq/UnboundZmqEventBus.java

@@ -27,6 +27,7 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.UnknownHostException;
+import java.time.Duration;
 import java.time.temporal.ChronoUnit;
 import java.util.ArrayList;
 import java.util.LinkedList;
@@ -76,7 +77,11 @@ class UnboundZmqEventBus implements EventBus {
   private ZMQ.Socket sub;
 
   UnboundZmqEventBus(
-      ZContext context, String publishConnection, String subscribeConnection, Secret secret) {
+      ZContext context,
+      String publishConnection,
+      String subscribeConnection,
+      Secret secret,
+      Duration heartbeatPeriod) {
     Require.nonNull("Secret", secret);
     StringBuilder builder = new StringBuilder();
     try (JsonOutput out = JSON.newOutput(builder)) {
@@ -136,11 +141,13 @@ class UnboundZmqEventBus implements EventBus {
             () -> {
               sub = context.createSocket(SocketType.SUB);
               sub.setIPv6(isSubAddressIPv6(publishConnection));
+              ZmqUtils.configureHeartbeat(sub, heartbeatPeriod, "SUB");
               sub.connect(publishConnection);
               sub.subscribe(new byte[0]);
 
               pub = context.createSocket(SocketType.PUB);
               pub.setIPv6(isSubAddressIPv6(subscribeConnection));
+              ZmqUtils.configureHeartbeat(pub, heartbeatPeriod, "PUB");
               pub.connect(subscribeConnection);
             });
     // Connections are already established

java/src/org/openqa/selenium/events/zeromq/ZeroMqEventBus.java

@@ -21,6 +21,7 @@
 
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.time.Duration;
 import java.util.function.Consumer;
 import org.openqa.selenium.events.EventBus;
 import org.openqa.selenium.events.EventListener;
@@ -38,17 +39,34 @@
 public class ZeroMqEventBus {
 
   private static final String EVENTS_SECTION = "events";
+  private static final int DEFAULT_HEARTBEAT_PERIOD_SECONDS = 60;
 
   private ZeroMqEventBus() {
     // Use the create method.
   }
 
   public static EventBus create(
       ZContext context, String publish, String subscribe, boolean bind, Secret secret) {
+    return create(
+        context,
+        publish,
+        subscribe,
+        bind,
+        secret,
+        Duration.ofSeconds(DEFAULT_HEARTBEAT_PERIOD_SECONDS));
+  }
+
+  public static EventBus create(
+      ZContext context,
+      String publish,
+      String subscribe,
+      boolean bind,
+      Secret secret,
+      Duration heartbeatPeriod) {
     if (bind) {
-      return new BoundZmqEventBus(context, publish, subscribe, secret);
+      return new BoundZmqEventBus(context, publish, subscribe, secret, heartbeatPeriod);
     }
-    return new UnboundZmqEventBus(context, publish, subscribe, secret);
+    return new UnboundZmqEventBus(context, publish, subscribe, secret, heartbeatPeriod);
   }
 
   public static EventBus create(Config config) {
@@ -85,10 +103,25 @@ public static EventBus create(Config config) {
                 });
 
     boolean bind = config.getBool(EVENTS_SECTION, "bind").orElse(false);
+    Duration heartbeatPeriod = getHeartbeatPeriod(config);
 
     SecretOptions secretOptions = new SecretOptions(config);
 
-    return create(new ZContext(), publish, subscribe, bind, secretOptions.getRegistrationSecret());
+    return create(
+        new ZContext(),
+        publish,
+        subscribe,
+        bind,
+        secretOptions.getRegistrationSecret(),
+        heartbeatPeriod);
+  }
+
+  private static Duration getHeartbeatPeriod(Config config) {
+    int periodSeconds =
+        config
+            .getInt(EVENTS_SECTION, "eventbus-heartbeat-period")
+            .orElse(DEFAULT_HEARTBEAT_PERIOD_SECONDS);
+    return Duration.ofSeconds(periodSeconds);
   }
 
   private static String mungeUri(URI base, String scheme, int port) {

java/src/org/openqa/selenium/events/zeromq/ZmqUtils.java

@@ -0,0 +1,103 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.openqa.selenium.events.zeromq;
+
+import java.time.Duration;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import org.zeromq.ZMQ;
+
+class ZmqUtils {
+
+  private static final Logger LOG = Logger.getLogger(ZmqUtils.class.getName());
+
+  // Minimum heartbeat interval: 1 second
+  private static final long MIN_HEARTBEAT_MS = 1_000L;
+  // Maximum heartbeat interval: ~24 days (to prevent overflow when multiplied by 6)
+  private static final long MAX_HEARTBEAT_MS = Integer.MAX_VALUE / 6;
+
+  private ZmqUtils() {}
+
+  /**
+   * Configures ZeroMQ heartbeat settings on a socket to prevent stale connections.
+   *
+   * <p>The heartbeat interval is clamped between 1 second and ~24 days to prevent integer overflow
+   * and ensure reasonable values. If the provided duration is outside this range, it will be
+   * adjusted and a warning will be logged.
+   *
+   * @param socket The ZMQ socket to configure
+   * @param heartbeatPeriod The heartbeat interval duration
+   * @param socketType The socket type name for logging (e.g., "SUB", "PUB", "XPUB", "XSUB")
+   */
+  static void configureHeartbeat(ZMQ.Socket socket, Duration heartbeatPeriod, String socketType) {
+    if (heartbeatPeriod != null && !heartbeatPeriod.isZero() && !heartbeatPeriod.isNegative()) {
+      long heartbeatMs = heartbeatPeriod.toMillis();
+      long clampedHeartbeatMs = clampHeartbeatInterval(heartbeatMs, socketType);
+
+      // Safe to cast to int now
+      int heartbeatIvl = (int) clampedHeartbeatMs;
+      int heartbeatTimeout = heartbeatIvl * 3;
+      int heartbeatTtl = heartbeatIvl * 6;
+
+      socket.setHeartbeatIvl(heartbeatIvl);
+      socket.setHeartbeatTimeout(heartbeatTimeout);
+      socket.setHeartbeatTtl(heartbeatTtl);
+
+      LOG.info(
+          String.format(
+              "ZMQ %s socket heartbeat configured: interval=%ds, timeout=%ds, ttl=%ds",
+              socketType, heartbeatIvl / 1000, heartbeatTimeout / 1000, heartbeatTtl / 1000));
+    }
+  }
+
+  /**
+   * Clamps the heartbeat interval to safe bounds and logs warnings if adjustments are made.
+   *
+   * @param heartbeatMs The heartbeat interval in milliseconds
+   * @param socketType The socket type for logging
+   * @return The clamped heartbeat interval
+   */
+  private static long clampHeartbeatInterval(long heartbeatMs, String socketType) {
+    if (heartbeatMs < MIN_HEARTBEAT_MS) {
+      logHeartbeatClampWarning(socketType, heartbeatMs, MIN_HEARTBEAT_MS, "below minimum");
+      return MIN_HEARTBEAT_MS;
+    }
+    if (heartbeatMs > MAX_HEARTBEAT_MS) {
+      logHeartbeatClampWarning(socketType, heartbeatMs, MAX_HEARTBEAT_MS, "exceeds maximum");
+      return MAX_HEARTBEAT_MS;
+    }
+    return heartbeatMs;
+  }
+
+  /**
+   * Logs a warning when the heartbeat interval is clamped.
+   *
+   * @param socketType The socket type
+   * @param originalMs The original interval value in milliseconds
+   * @param clampedMs The clamped interval value in milliseconds
+   * @param reason The reason for clamping
+   */
+  private static void logHeartbeatClampWarning(
+      String socketType, long originalMs, long clampedMs, String reason) {
+    LOG.log(
+        Level.WARNING,
+        String.format(
+            "ZMQ %s socket heartbeat interval %ds is %s, clamping to %ds",
+            socketType, originalMs / 1000, reason, clampedMs / 1000));
+  }
+}

java/src/org/openqa/selenium/grid/server/EventBusFlags.java

@@ -65,6 +65,12 @@ public class EventBusFlags implements HasRoles {
       example = "\"org.openqa.selenium.events.zeromq.ZeroMqEventBus\"")
   private String implementation;
 
+  @Parameter(
+      names = {"--eventbus-heartbeat-period"},
+      description = "How often, in seconds, will the EventBus socket send heartbeats")
+  @ConfigValue(section = EVENTS_SECTION, name = "eventbus-heartbeat-period", example = "30")
+  private int eventbusHeartbeatPeriod;
+
   @Override
   public Set<Role> getRoles() {
     return ImmutableSet.of(EVENT_BUS_ROLE);

java/src/org/openqa/selenium/grid/server/EventBusOptions.java

@@ -17,6 +17,7 @@
 
 package org.openqa.selenium.grid.server;
 
+import java.time.Duration;
 import org.openqa.selenium.events.EventBus;
 import org.openqa.selenium.grid.config.Config;
 import org.openqa.selenium.internal.Require;
@@ -25,6 +26,7 @@ public class EventBusOptions {
 
   static final String EVENTS_SECTION = "events";
   private static final String DEFAULT_CLASS = "org.openqa.selenium.events.zeromq.ZeroMqEventBus";
+  private static final int DEFAULT_HEARTBEAT_PERIOD = 60;
   private final Config config;
   private volatile EventBus bus;
 
@@ -47,6 +49,12 @@ public EventBus getEventBus() {
     return localBus;
   }
 
+  public Duration getHeartbeatPeriod() {
+    int period =
+        config.getInt(EVENTS_SECTION, "eventbus-heartbeat-period").orElse(DEFAULT_HEARTBEAT_PERIOD);
+    return Duration.ofSeconds(period);
+  }
+
   private EventBus createBus() {
     return config.getClass(EVENTS_SECTION, "implementation", EventBus.class, DEFAULT_CLASS);
   }