Use a dedicated thread pool for disk cache garbage collection.

The ExecutorService created in RemoteModule#beforeCommand is intended to have command scope, so it won't be available during idle periods. (The current state doesn't work, either, because we pass it into the DiskCacheGarbageCollectorIdleTask before initializing it. Oops.)

PiperOrigin-RevId: 679497012
Change-Id: I8e791580c2db078c6d39cb760936b8fbcba4ed3d

src/main/java/com/google/devtools/build/lib/remote/RemoteModule.java

@@ -344,8 +344,7 @@ public void beforeCommand(CommandEnvironment env) throws AbruptExitException {
 
     if (enableDiskCache) {
       var gcIdleTask =
-          DiskCacheGarbageCollectorIdleTask.create(
-              remoteOptions, env.getWorkingDirectory(), executorService);
+          DiskCacheGarbageCollectorIdleTask.create(remoteOptions, env.getWorkingDirectory());
       if (gcIdleTask != null) {
         env.addIdleTask(gcIdleTask);
       }

src/main/java/com/google/devtools/build/lib/remote/disk/DiskCacheGarbageCollectorIdleTask.java

@@ -17,6 +17,7 @@
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.flogger.GoogleLogger;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.google.devtools.build.lib.remote.disk.DiskCacheGarbageCollector.CollectionPolicy;
 import com.google.devtools.build.lib.remote.disk.DiskCacheGarbageCollector.CollectionStats;
 import com.google.devtools.build.lib.remote.options.RemoteOptions;
@@ -26,6 +27,7 @@
 import java.time.Duration;
 import java.util.Optional;
 import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import javax.annotation.Nullable;
 
 /** An {@link IdleTask} to run a {@link DiskCacheGarbageCollector}. */
@@ -35,6 +37,10 @@ public final class DiskCacheGarbageCollectorIdleTask implements IdleTask {
   private final Duration delay;
   private final DiskCacheGarbageCollector gc;
 
+  private static final ExecutorService executorService =
+      Executors.newCachedThreadPool(
+          new ThreadFactoryBuilder().setNameFormat("disk-cache-gc-%d").build());
+
   private DiskCacheGarbageCollectorIdleTask(Duration delay, DiskCacheGarbageCollector gc) {
     this.delay = delay;
     this.gc = gc;
@@ -50,7 +56,7 @@ private DiskCacheGarbageCollectorIdleTask(Duration delay, DiskCacheGarbageCollec
    */
   @Nullable
   public static DiskCacheGarbageCollectorIdleTask create(
-      RemoteOptions remoteOptions, Path workingDirectory, ExecutorService executorService) {
+      RemoteOptions remoteOptions, Path workingDirectory) {
     if (remoteOptions.diskCache == null || remoteOptions.diskCache.isEmpty()) {
       return null;
     }