Guava is a set of core Java libraries from Google that includes new collection
types (such as multimap and multiset), immutable collections, a graph library,
and utilities for concurrency, I/O, hashing, primitives, strings, and more! It
is widely used on most Java projects within Google, and widely used by many
other companies as well.



Guava comes in two flavors:

import java.util.Collections;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.Executor;
import java.util.logging.Level;

/**
 * A list of listeners for implementing a concurrency friendly observable object.
 *
 * <p>Listeners are registered once via {@link #addListener} and then may be invoked by {@linkplain
 * #enqueue enqueueing} and then {@linkplain #dispatch dispatching} events.
 *

 * Manages a pool of byte buffers to reduce garbage collection overhead.
 *
 * Performance optimizations:
 * - Uses ConcurrentLinkedQueue for O(1) operations
 * - Lock-free operations for better concurrency
 * - Proper buffer validation and limits
 */
public class BufferCache {

    /**
     * Private constructor to prevent instantiation of this utility class.
     */
    private BufferCache() {

     */
    @CanIgnoreReturnValue
    @GwtIncompatible("java.lang.ref.WeakReference")
    public InternerBuilder weak() {
      this.strong = false;
      return this;
    }

    /**
     * Sets the concurrency level that will be used by the to-be-built {@link Interner}.
     *
     * @see MapMaker#concurrencyLevel(int)
     */
    @CanIgnoreReturnValue
    public InternerBuilder concurrencyLevel(int concurrencyLevel) {

    exec.shutdown();
    exec.awaitTermination(100, MILLISECONDS);
  }

  /**
   * Tests that all listeners complete, even if they were added before or after the future was
   * finishing. Also acts as a concurrency test to make sure the locking is done correctly when a
   * future is finishing so that no listeners can be lost.
   */
  public void testAllListenersCompleteSuccessfully()

  }

  /**
   * Guides the allowed concurrency among update operations. Used as a hint for internal sizing. The
   * table is internally partitioned to try to permit the indicated number of concurrent updates
   * without contention. Because assignment of entries to these partitions is not necessarily
   * uniform, the actual concurrency observed may vary. Ideally, you should choose a value to

            // Verify it works by testing a known mapping
            assertEquals("application/pdf", map.getMimeType("pdf"));
        }
    }

    @Nested
    @DisplayName("Performance and concurrency")
    class PerformanceTests {

        @Test
        @DisplayName("Should handle multiple lookups efficiently")
        void testMultipleLookups() throws IOException {

	azMeta := map[string]*string{}
	for k, v := range meta {
		azMeta[k] = to.Ptr(v)
	}
	resp, err := az.clnt.UploadStream(ctx, az.Bucket, az.getDest(object), io.LimitReader(r, length), &azblob.UploadStreamOptions{
		Concurrency: 4,
		AccessTier:  az.tier(), // set tier if specified
		Metadata:    azMeta,
	})
	if err != nil {
		return "", azureToObjectError(err, az.Bucket, az.getDest(object))
	}
	vid := ""
	if resp.VersionID != nil {

        if (offset + SIGNATURE_OFFSET + SIGNATURE_LENGTH > data.length) {
            throw new IllegalArgumentException("Signature field exceeds data buffer size");
        }

        // Use fine-grained locking for better concurrency
        this.signingLock.lock();
        try {
            if (this.closed) {
                throw new IllegalStateException("SigningDigest is closed");
            }

            // zero out signature field

/// tip

By adding the `standard`, Uvicorn will install and use some recommended extra dependencies.

That including `uvloop`, the high-performance drop-in replacement for `asyncio`, that provides the big concurrency performance boost.

When you install FastAPI with something like `pip install "fastapi[standard]"` you already get `uvicorn[standard]` as well.

///

## Run the Server Program { #run-the-server-program }