diff --git a/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/GrpcServer.java b/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/GrpcServer.java
index 4f569c9c..ec234a05 100644
--- a/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/GrpcServer.java
+++ b/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/GrpcServer.java
@@ -63,7 +63,7 @@ public void start() throws IOException {
             new Thread() {
               @Override
               public void run() {
-                timeoutHandler.cancelOutstanding();
+                timeoutHandler.cancelOutstandingAndStopScheduling();
                 try {
                   GrpcServer.this.stop();
                 } catch (InterruptedException e) {
diff --git a/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/Main.java b/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/Main.java
index 06e2c434..12f28f74 100644
--- a/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/Main.java
+++ b/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/Main.java
@@ -3,7 +3,6 @@
 import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import java.util.concurrent.ScheduledThreadPoolExecutor;
 import org.apache.commons.cli.CommandLine;
 import org.apache.commons.cli.CommandLineParser;
 import org.apache.commons.cli.DefaultParser;
@@ -22,8 +21,7 @@ public static void main(String[] args) throws IOException, InterruptedException
     line = commandLineOptions(args);
     Main main = new Main();
 
-    TimeoutHandler timeoutHander =
-        new TimeoutHandler(new ScheduledThreadPoolExecutor(1), main.idleTimeout());
+    TimeoutHandler timeoutHander = new TimeoutHandler(main.idleTimeout());
     main.runServer(timeoutHander);
   }
 
diff --git a/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/TimeoutHandler.java b/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/TimeoutHandler.java
index 638648c1..6543c612 100644
--- a/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/TimeoutHandler.java
+++ b/java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators/TimeoutHandler.java
@@ -3,6 +3,7 @@
 import com.google.errorprone.annotations.concurrent.GuardedBy;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 import org.slf4j.Logger;
@@ -11,7 +12,11 @@
 public class TimeoutHandler {
   private static final Logger logger = LoggerFactory.getLogger(TimeoutHandler.class);
 
+  // Anything which shuts down the executor, or relies on it not being shutdown, must do so under
+  // this lock.
+  @GuardedBy("lastFutureLock")
   private final ScheduledExecutorService executor;
+
   private final int timeoutSeconds;
   private final AtomicInteger inFlightRequests = new AtomicInteger(0);
 
@@ -20,8 +25,8 @@ public class TimeoutHandler {
   @GuardedBy("lastFutureLock")
   private ScheduledFuture<?> lastFuture = null;
 
-  public TimeoutHandler(ScheduledExecutorService executor, int timeoutSeconds) {
-    this.executor = executor;
+  public TimeoutHandler(int timeoutSeconds) {
+    this.executor = new ScheduledThreadPoolExecutor(1);
     this.timeoutSeconds = timeoutSeconds;
     schedule();
   }
@@ -45,6 +50,12 @@ void schedule() {
       if (last != null) {
         last.cancel(true);
       }
+      if (this.executor.isShutdown()) {
+        // If the executor is already shutdown, the process is already terminating - we neither can
+        // (because it's shutdown) nor need to (because we're about to terminate) schedule a new
+        // task.
+        return;
+      }
       this.lastFuture =
           this.executor.schedule(
               () -> {
@@ -59,13 +70,19 @@ void schedule() {
     }
   }
 
-  public void cancelOutstanding() {
+  /**
+   * Cancel any outstanding scheduled tasks, and shut down any background threads.
+   *
+   * <p>This object becomes useless after this method is called - it will not perform its timeout
+   * functionality any more.
+   */
+  public void cancelOutstandingAndStopScheduling() {
     synchronized (lastFutureLock) {
       if (lastFuture != null) {
         lastFuture.cancel(true);
         lastFuture = null;
       }
+      this.executor.shutdownNow();
     }
-    this.executor.shutdownNow();
   }
 }