详解Spring Cloud中Hystrix 线程隔离导致ThreadLocal数据丢失

public class CustomThreadLocal {  static ThreadLocal<String> threadLocal = new ThreadLocal<>();  public static void main(String[] args) {    new Thread(new Runnable() {      @Override      public void run() {        CustomThreadLocal.threadLocal.set("猿天地");        new Service().call();      }    }).start();  }}class Service {  public void call() {    System.out.println("Service:" + Thread.currentThread().getName());    System.out.println("Service:" + CustomThreadLocal.threadLocal.get());    new Dao().call();  }}class Dao {  public void call() {    System.out.println("==========================");    System.out.println("Dao:" + Thread.currentThread().getName());    System.out.println("Dao:" + CustomThreadLocal.threadLocal.get());  }}

public class CustomThreadLocal {  static ThreadLocal<String> threadLocal = new ThreadLocal<>();  public static void main(String[] args) {    new Thread(new Runnable() {      @Override      public void run() {        CustomThreadLocal.threadLocal.set("猿天地");        new Service().call();      }    }).start();  }}class Service {  public void call() {    System.out.println("Service:" + Thread.currentThread().getName());    System.out.println("Service:" + CustomThreadLocal.threadLocal.get());    //new Dao().call();    new Thread(new Runnable() {      @Override      public void run() {        new Dao().call();      }    }).start();  }}class Dao {  public void call() {    System.out.println("==========================");    System.out.println("Dao:" + Thread.currentThread().getName());    System.out.println("Dao:" + CustomThreadLocal.threadLocal.get());  }}

static ThreadLocal<String> threadLocal = new InheritableThreadLocal<>();

public class Thread implements Runnable {  ThreadLocal.ThreadLocalMap threadLocals = null;}

public void set(T value) {  Thread t = Thread.currentThread();  ThreadLocalMap map = getMap(t);  if (map != null)    map.set(this, value);  else    createMap(t, value);}

public T get() {  Thread t = Thread.currentThread();  ThreadLocalMap map = getMap(t);  if (map != null) {    ThreadLocalMap.Entry e = map.getEntry(this);    if (e != null) {       @SuppressWarnings("unchecked")       T result = (T)e.value;       return result;    }  }  return setInitialValue();}

public class InheritableThreadLocal<T> extends ThreadLocal<T> {  /**   * Computes the child's initial value for this inheritable thread-local   * variable as a function of the parent's value at the time the child   * thread is created. This method is called from within the parent   * thread before the child is started.   * <p>   * This method merely returns its input argument, and should be overridden   * if a different behavior is desired.   *   * @param parentValue the parent thread's value   * @return the child thread's initial value   */  protected T childValue(T parentValue) {    return parentValue;  }  /**   * Get the map associated with a ThreadLocal.   *   * @param t the current thread   */  ThreadLocalMap getMap(Thread t) {    return t.inheritableThreadLocals;  }  /**   * Create the map associated with a ThreadLocal.   *   * @param t the current thread   * @param firstValue value for the initial entry of the table.   */  void createMap(Thread t, T firstValue) {    t.inheritableThreadLocals = new ThreadLocalMap(this, firstValue);  }}

if (parent.inheritableThreadLocals != null)  this.inheritableThreadLocals =        ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);

static ThreadLocalMap createInheritedMap(ThreadLocalMap parentMap) {    return new ThreadLocalMap(parentMap);  }

 private ThreadLocalMap(ThreadLocalMap parentMap) {   Entry[] parentTable = parentMap.table;   int len = parentTable.length;   setThreshold(len);   table = new Entry[len];   for (int j = 0; j < len; j++) {      Entry e = parentTable[j];      if (e != null) {        @SuppressWarnings("unchecked")        ThreadLocal<Object> key = (ThreadLocal<Object>) e.get();        if (key != null) {          Object value = key.childValue(e.value);          Entry c = new Entry(key, value);          int h = key.threadLocalHashCode & (len - 1);          while (table[h] != null)            h = nextIndex(h, len);          table[h] = c;          size++;        }      }    }}

public class CustomThreadLocal {  static ThreadLocal<String> threadLocal = new InheritableThreadLocal<>();  static ExecutorService pool = Executors.newFixedThreadPool(2);  public static void main(String[] args) {    for(int i=0;i<100;i++) {       int j = i;      pool.execute(new Thread(new Runnable() {        @Override        public void run() {          CustomThreadLocal.threadLocal.set("猿天地"+j);          new Service().call();        }      }));    }  }}class Service {  public void call() {    CustomThreadLocal.pool.execute(new Runnable() {      @Override      public void run() {        new Dao().call();      }    });  }}class Dao {  public void call() {     System.out.println("Dao:" + CustomThreadLocal.threadLocal.get());  }}

<dependency>  <groupId>com.alibaba</groupId>  <artifactId>transmittable-thread-local</artifactId>  <version>2.2.0</version></dependency>

static TransmittableThreadLocal<String> threadLocal = new TransmittableThreadLocal<>();static ExecutorService pool = TtlExecutors.getTtlExecutorService(Executors.newFixedThreadPool(2));