threadPool.shutdown();
    threadPool.awaitTermination(300, SECONDS);

    // Since we're not doing any more cache operations, and the cache only expires/evicts when doing
    // other operations, the cache and the removal queue won't change from this point on.

    // Verify that each received removal notification was valid
    for (RemovalNotification<String, String> notification : removalListener) {

    threadPool.shutdown();
    threadPool.awaitTermination(300, SECONDS);

    // Since we're not doing any more cache operations, and the cache only expires/evicts when doing
    // other operations, the cache and the removal queue won't change from this point on.

    // Verify that each received removal notification was valid
    for (RemovalNotification<String, String> notification : removalListener) {

   * once after loading completes). Much internal cache management is performed at the segment
   * granularity. For example, access queues and write queues are kept per segment when they are
   * required by the selected eviction algorithm. As such, when writing unit tests it is not

// have been executed. Note that "execution" here refers to kernel execution /
// scheduling of copies, etc. Similar to sync execution, it doesn't guarantee
// that lower level device queues (like GPU streams) have been flushed.
//
// This call may not block for execution of ops enqueued concurrently with this
// call.
TF_CAPI_EXPORT extern void TFE_ExecutorWaitForAllPendingNodes(

    assertFalse(segment.clearValueForTesting(key, hash, valueRef));
    segment.setWeakValueReferenceForTesting(entry, valueRef);
    assertTrue(segment.clearValueForTesting(key, hash, valueRef));
  }

  // reference queues

  public void testDrainKeyReferenceQueueOnWrite() {
    for (MapMaker maker : allWeakKeyStrengthMakers()) {
      MapMakerInternalMap<Object, Object, ?, ?> map = makeMap(maker.concurrencyLevel(1));

    assertFalse(segment.clearValueForTesting(key, hash, valueRef));
    segment.setWeakValueReferenceForTesting(entry, valueRef);
    assertTrue(segment.clearValueForTesting(key, hash, valueRef));
  }

  // reference queues

  public void testDrainKeyReferenceQueueOnWrite() {
    for (MapMaker maker : allWeakKeyStrengthMakers()) {
      MapMakerInternalMap<Object, Object, ?, ?> map = makeMap(maker.concurrencyLevel(1));

 * rate limit itself.
 *
 * {@snippet :
 * class CrawlingService extends AbstractScheduledService {
 *   private Set<Uri> visited;
 *   private Queue<Uri> toCrawl;
 *   protected void startUp() throws Exception {
 *     toCrawl = readStartingUris();
 *   }
 *
 *   protected void runOneIteration() throws Exception {
 *     Uri uri = toCrawl.remove();

	bucketNotificationBuf := `<NotificationConfiguration><QueueConfiguration><Event>s3:ObjectCreated:Put</Event><Filter><S3Key><FilterRule><Name>prefix</Name><Value>images/</Value></FilterRule></S3Key></Filter><Id>1</Id><Queue>arn:minio:sqs:us-east-1:444455556666:webhook</Queue></QueueConfiguration></NotificationConfiguration>`
	// generate a random bucket Name.
	bucketName := getRandomBucketName()
	// HTTP request to create the bucket.

 *  **TunnelRequest is gone.** It specified how to connect to an HTTP proxy.
    OkHttp 2 uses the new `Request` class for this.

 *  **Dispatcher** is a new class that manages the queue of asynchronous calls. It
    implements limits on total in-flight calls and in-flight calls per host.

#### Implementation changes

 * Support Android `TrafficStats` socket tagging.

    }
}
```

## 9. Performance and Optimization

### 9.1 Witness Event Batching
```java
public class WitnessEventBatcher {
    private final Queue<WitnessNotification> pendingNotifications;
    private final ScheduledExecutorService scheduler;
    private final int batchSize = 10;
    private final long batchTimeout = 100;  // 100ms