cleanup due to low memory on some other thread

platform/util/src/com/intellij/openapi/util/LowMemoryWatcher.java

@@ -25,6 +25,10 @@ import java.lang.management.ManagementFactory;
 import java.lang.management.MemoryNotificationInfo;
 import java.lang.management.MemoryPoolMXBean;
 import java.lang.management.MemoryType;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
 
 /**
  * @author Eugene Zhuravlev
@@ -36,6 +40,34 @@ public class LowMemoryWatcher {
   private static final Logger LOG = Logger.getInstance("#com.intellij.openapi.util.LowMemoryWatcher");
   
   private static final WeakList<LowMemoryWatcher> ourInstances = new WeakList<LowMemoryWatcher>();
+  private static final ThreadPoolExecutor ourExecutor = new ThreadPoolExecutor(0, 1, 10, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(2), new ThreadFactory() {
+    @Override
+    public Thread newThread(Runnable r) {
+      return new Thread(r, "LowMemoryWatcher janitor");
+    }
+  });
+  private static boolean ourSubmitted;
+  private static final Runnable ourJanitor = new Runnable() {
+    @Override
+    public void run() {
+      try {
+        for (LowMemoryWatcher watcher : ourInstances) {
+          try {
+            watcher.myRunnable.run();
+          }
+          catch (Throwable e) {
+            LOG.info(e);
+          }
+        }
+      }
+      finally {
+        synchronized (ourJanitor) {
+          //noinspection AssignmentToStaticFieldFromInstanceMethod
+          ourSubmitted = false;
+        }
+      }
+    }
+  };
 
   private final Runnable myRunnable;
 
@@ -52,12 +84,11 @@ public class LowMemoryWatcher {
     ((NotificationEmitter)ManagementFactory.getMemoryMXBean()).addNotificationListener(new NotificationListener() {
       public void handleNotification(Notification n, Object hb) {
         if (MemoryNotificationInfo.MEMORY_THRESHOLD_EXCEEDED.equals(n.getType()) || MemoryNotificationInfo.MEMORY_COLLECTION_THRESHOLD_EXCEEDED.equals(n.getType())) {
-          for (LowMemoryWatcher watcher : ourInstances) {
-            try {
-              watcher.myRunnable.run();
-            }
-            catch (Throwable e) {
-              LOG.info(e);
+          synchronized (ourJanitor) {
+            if (!ourSubmitted) {
+              //noinspection AssignmentToStaticFieldFromInstanceMethod
+              ourSubmitted = true;
+              ourExecutor.submit(ourJanitor);
             }
           }
         }