如何通过@TraceCrossThread注解解决多线程丢失traceId的问题？

可以通过创建自定义的TraceableRunnable和TraceableCallable类，并在这些类上使用@TraceCrossThread注解。这两个类分别包装了原始的Runnable和Callable对象，并在它们的run()和call()方法中调用原始对象的相应方法。当这些包装类被提交到线程池执行时，Skywalking会自动增强它们，确保traceId能够跨线程传递。
示例代码如下：

// TraceableRunnable 示例 
@TraceCrossThread 
public class TraceableRunnable implements Runnable { 
private final Runnable runnable; 

public TraceableRunnable(final Runnable runnable) { 
this.runnable = runnable; 
} 

@Override 
public void run() { 
runnable.run(); 
} 
} 

// TraceableCallable 示例 
@TraceCrossThread 
public class TraceableCallable<T> implements Callable<T> { 
private final Callable<T> callable; 

public TraceableCallable(final Callable<T> callable) { 
this.callable = callable; 
} 

@Override 
public T call() throws Exception { 
return callable.call(); 
} 
}