仅当n个线程正在运行时才停止线程

import threading
import time

# 计数器
counter = 0
# 锁
lock = threading.Lock()
# 条件变量
condition = threading.Condition(lock)

def worker():
    global counter
    with lock:
        counter += 1
        print(f"Thread {threading.current_thread().name} started. Counter: {counter}")
    
    # 模拟工作
    time.sleep(2)
    
    with lock:
        counter -= 1
        print(f"Thread {threading.current_thread().name} finished. Counter: {counter}")
        condition.notify_all()

def main():
    n = 5  # 需要运行的线程数量
    threads = []
    
    for i in range(n):
        t = threading.Thread(target=worker)
        threads.append(t)
        t.start()
    
    with lock:
        while counter < n:
            condition.wait()
    
    print("All threads have started and finished.")

if __name__ == "__main__":
    main()