import java.util.UUID;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingDeque;

To see the difference, imagine the following story about burgers:

### Concurrent Burgers { #concurrent-burgers }

You go with your crush to get fast food, you stand in line while the cashier takes the orders from the people in front of you. 😍

<img src="/img/async/concurrent-burgers/concurrent-burgers-01.png" class="illustration">

import okhttp3.internal.concurrent.assertLockHeld
import okhttp3.internal.concurrent.assertLockNotHeld
import okhttp3.internal.concurrent.withLock
import okhttp3.internal.http.ExchangeCodec
import okhttp3.internal.http.RealInterceptorChain
import okhttp3.internal.http1.Http1ExchangeCodec
import okhttp3.internal.http2.ConnectionShutdownException
import okhttp3.internal.http2.ErrorCode
import okhttp3.internal.http2.FlowControlListener

import java.net.Socket
import java.util.concurrent.TimeUnit
import javax.net.SocketFactory
import javax.net.ssl.HostnameVerifier
import javax.net.ssl.HttpsURLConnection
import javax.net.ssl.SSLSocketFactory
import okhttp3.internal.RecordingOkAuthenticator
import okhttp3.internal.concurrent.TaskFaker
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.concurrent.withLock

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.Deque;
import java.util.List;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

	CurrentSendCalls int64 // CurrentSendCalls is the number of concurrent async Send calls to all targets
	CurrentQueue     int   // Populated if target has a store.
	TotalEvents      int64
	FailedEvents     int64 // Number of failed events per target
}

// TargetList - holds list of targets indexed by target ID.
type TargetList struct {
	// The number of concurrent async Send calls to all targets
	currentSendCalls  atomic.Int64

import android.annotation.SuppressLint
import java.util.concurrent.ThreadFactory
import java.util.concurrent.TimeUnit
import java.util.logging.Handler
import java.util.logging.Level
import java.util.logging.LogManager
import java.util.logging.LogRecord
import java.util.logging.Logger
import okhttp3.internal.buildConnectionPool
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.concurrent.withLock

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import jcifs.CIFSContext;
import jcifs.Configuration;

- **Logging Abstraction** (`org.codelibs.core.log`) - Flexible logging system supporting JCL (Jakarta Commons Logging) and JUL (Java Util Logging)
- **Concurrent Utilities** (`org.codelibs.core.concurrent`) - Thread-safe collections and concurrency helpers using modern concurrent APIs
- **Crypto & Security** (`org.codelibs.core.crypto`, `org.codelibs.core.security`) - Basic cryptographic utilities, message digest operations, and secure random generation