from multiprocessing import Event,Process
from time import sleep

def wait_event1():
    print("1想操作臨界區資源")
    e.wait()
    print("1開始操作臨界區資源",e.is_set())
    with open("file") as f:
        print(f.read())
def wait_event2():
    print("2也想操作臨界區資源")
    # 超時3秒檢測
    e.wait(3)
    # 判斷是否被設定
    if e.is_set():
        
 
print("2開始操作臨界區資源",e.is_set())
        with open("file") as f:
            print(f.read())
    else:
        print("2不能操作")       

# 建立事件物件
e = Event()
p1 = Process(target = wait_event1)
p2 = Process(target = wait_event2)
p1.start()
p2.start()
print("主程序操作")
with open("file",'w') as f:
    f.write(
 
"HELLO WORD")

# 延遲4秒釋放臨界區
sleep(4)
# 釋放臨界區資源
e.set()
print("釋放臨界區")
p1.join()
p2.join()