fix: fully encapsulating rejected execution handling

CHANGELOG.md

@@ -8,6 +8,8 @@
 
 #### Improvements
 
+* Fix #6863: ensuring SerialExecutor does not throw RejectedExecutionException to prevent unnecessary error logs
+
 #### Dependency Upgrade
 
 #### New Features

kubernetes-client/src/main/java/io/fabric8/kubernetes/client/dsl/internal/ExecWebSocketListener.java

@@ -47,7 +47,6 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
@@ -371,23 +370,19 @@ public void onClose(WebSocket webSocket, int code, String reason) {
     }
     closeWebSocketOnce(code, reason);
     LOGGER.debug("Exec Web Socket: On Close with code:[{}], due to: [{}]", code, reason);
-    try {
-      serialExecutor.execute(() -> {
-        try {
-          if (exitCode.complete(null)) {
-            // this is expected for processes that don't terminate - uploads for example
-            LOGGER.debug("Exec Web Socket: completed with a null exit code - no status was received prior to onClose");
-          }
-          cleanUpOnce();
-        } finally {
-          if (listener != null) {
-            listener.onClose(code, reason);
-          }
+    serialExecutor.execute(() -> {
+      try {
+        if (exitCode.complete(null)) {
+          // this is expected for processes that don't terminate - uploads for example
+          LOGGER.debug("Exec Web Socket: completed with a null exit code - no status was received prior to onClose");
         }
-      });
-    } catch (RejectedExecutionException e) {
-      LOGGER.debug("Client already shutdown, aborting normal closure", e);
-    }
+        cleanUpOnce();
+      } finally {
+        if (listener != null) {
+          listener.onClose(code, reason);
+        }
+      }
+    });
   }
 
   @Override

kubernetes-client/src/main/java/io/fabric8/kubernetes/client/dsl/internal/PortForwarderWebsocketListener.java

@@ -32,7 +32,6 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
-import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.BooleanSupplier;
 
@@ -130,27 +129,23 @@ public void onMessage(WebSocket webSocket, ByteBuffer buffer) {
     } else {
       // Data
       if (out != null) {
-        try {
-          serialExecutor.execute(() -> {
-            try {
-              while (buffer.hasRemaining()) {
-                int written = out.write(buffer); // channel byte already skipped
-                if (written == 0) {
-                  // out is non-blocking, prevent a busy loop
-                  Thread.sleep(50);
-                }
-              }
-              webSocket.request();
-            } catch (IOException | InterruptedException e) {
-              if (e instanceof InterruptedException) {
-                Thread.currentThread().interrupt();
+        serialExecutor.execute(() -> {
+          try {
+            while (buffer.hasRemaining()) {
+              int written = out.write(buffer); // channel byte already skipped
+              if (written == 0) {
+                // out is non-blocking, prevent a busy loop
+                Thread.sleep(50);
               }
-              clientError(webSocket, "forwarding data to the client", e);
             }
-          });
-        } catch (RejectedExecutionException e) {
-          // just ignore 
-        }
+            webSocket.request();
+          } catch (IOException | InterruptedException e) {
+            if (e instanceof InterruptedException) {
+              Thread.currentThread().interrupt();
+            }
+            clientError(webSocket, "forwarding data to the client", e);
+          }
+        });
       }
     }
   }

kubernetes-client/src/main/java/io/fabric8/kubernetes/client/informers/impl/cache/ProcessorStore.java

@@ -113,7 +113,7 @@ public void retainAll(Set<String> nextKeys, Consumer<Executor> cacheStateComplet
       }
     });
     if (cacheStateComplete != null) {
-      cacheStateComplete.accept(this.processor::executeIfPossible);
+      cacheStateComplete.accept(this.processor.getSerialExecutor()::execute);
     }
   }
 

kubernetes-client/src/main/java/io/fabric8/kubernetes/client/informers/impl/cache/SharedProcessor.java

@@ -26,7 +26,6 @@
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.Executor;
-import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.function.Consumer;
@@ -108,20 +107,16 @@ public void distribute(Consumer<ProcessorListener<T>> operation, boolean isSync)
     } finally {
       lock.readLock().unlock();
     }
-    try {
-      executor.execute(() -> {
-        for (ProcessorListener<T> listener : toCall) {
-          try {
-            operation.accept(listener);
-          } catch (Exception ex) {
-            log.error("{} failed invoking {} event handler: {}", informerDescription, listener.getHandler(), ex.getMessage(),
-                ex);
-          }
+    executor.execute(() -> {
+      for (ProcessorListener<T> listener : toCall) {
+        try {
+          operation.accept(listener);
+        } catch (Exception ex) {
+          log.error("{} failed invoking {} event handler: {}", informerDescription, listener.getHandler(), ex.getMessage(),
+              ex);
         }
-      });
-    } catch (RejectedExecutionException e) {
-      // do nothing
-    }
+      }
+    });
   }
 
   public boolean shouldResync() {
@@ -202,11 +197,8 @@ public Optional<Long> getMinimalNonZeroResyncPeriod() {
     }
   }
 
-  public void executeIfPossible(Runnable runnable) {
-    try {
-      this.executor.execute(runnable);
-    } catch (RejectedExecutionException e) {
-      // already shutdown
-    }
+  public SerialExecutor getSerialExecutor() {
+    return executor;
   }
+
 }

kubernetes-client/src/main/java/io/fabric8/kubernetes/client/utils/internal/SerialExecutor.java

@@ -15,6 +15,9 @@
  */
 package io.fabric8.kubernetes.client.utils.internal;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.util.Queue;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingDeque;
@@ -30,6 +33,9 @@
  * Added shutdown support
  */
 public class SerialExecutor implements Executor {
+
+  private static final Logger log = LoggerFactory.getLogger(SerialExecutor.class);
+
   final Queue<Runnable> tasks = new LinkedBlockingDeque<>();
   final Executor executor;
   Runnable active;
@@ -41,10 +47,14 @@ public SerialExecutor(Executor executor) {
     this.executor = executor;
   }
 
+  /**
+   * Executes the given command at some time in the future. Unlike a normal {@link Executor}, it will
+   * not throw a {@link RejectedExecutionException}
+   */
   @Override
   public synchronized void execute(final Runnable r) {
     if (shutdown) {
-      throw new RejectedExecutionException();
+      log.debug("Task submitted after the executor was shutdown");
     }
     tasks.offer(() -> {
       try {
@@ -72,7 +82,11 @@ public synchronized void execute(final Runnable r) {
 
   protected synchronized void scheduleNext() {
     if ((active = tasks.poll()) != null) {
-      executor.execute(active);
+      try {
+        executor.execute(active);
+      } catch (RejectedExecutionException e) {
+        log.debug("Underlying executor rejected execution", e);
+      }
     }
   }
 
@@ -94,4 +108,5 @@ public void shutdownNow() {
   public boolean isShutdown() {
     return shutdown;
   }
+
 }