[Feature] ThreadlessExecutor waitAndDrain method seems to not match its annotation.

[CycleMaker]

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Apache Dubbo Component

Java SDK (apache/dubbo)

Descriptions

This is the source code of the ThreadlessExecutor waitAndDrain method:

dubbo/dubbo-common/src/main/java/org/apache/dubbo/common/threadpool/ThreadlessExecutor.java

Lines 52 to 80 in ca7151e

	/**
	* Waits until there is a task, executes the task and all queued tasks (if there're any). The task is either a normal
	* response or a timeout response.
	*/
	public void waitAndDrain(long deadline) throws InterruptedException {
	throwIfInterrupted();
	Runnable runnable = queue.poll();
	if (runnable == null) {
	if (waiter.compareAndSet(null, Thread.currentThread())) {
	try {
	while ((runnable = queue.poll()) == null && waiter.get() == Thread.currentThread()) {
	long restTime = deadline - System.nanoTime();
	if (restTime <= 0) {
	return;
	}
	LockSupport.parkNanos(this, restTime);
	throwIfInterrupted();
	}
	} finally {
	waiter.compareAndSet(Thread.currentThread(), null);
	}
	}
	}
	do {
	if (runnable != null) {
	runnable.run();
	}
	} while ((runnable = queue.poll()) != null);
	}

It seems that if waitAndDrain is called twice in a multi-threaded scenario, there will be no wait on the second execution because if the cas fails, it will return. Here is my test code:

@test
void testV2() throws InterruptedException {
new Thread(()->{
try {
executor.waitAndDrain(Long.MAX_VALUE);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}).start();
executor.waitAndDrain(Long.MAX_VALUE);
System.out.println("wait not worked");
}

There is no example in Dubbo where waitAndDrain is executed through the same threadlessExecutor across multiple threads, so there shouldn't be any issues. I don't know if this is a bug.

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[AlbumenJ]

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