python線程中的全域變數與局部變數

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在python多線程開發中，全域變數是多個線程共用的資料，局部變數是各自線程的，非共用的。

 如下幾種寫法都是可以的：

第一種：將列表當成參數傳遞給線程

from threading import Threadimport timedef work1(nums):    nums.append(44)    print("----in work1---",nums)def work2(nums):    #延時一會，保證t1線程中的事情做完    time.sleep(1)    print("----in work2---",nums)if __name__==‘__main__‘:    g_nums = [11, 22, 33]    t1 = Thread(target=work1, args=(g_nums,)) #這種寫法是將列表當成參數傳遞    t1.start()    t2 = Thread(target=work2, args=(g_nums,))    t2.start()

第二種：不傳遞，直接用

from threading import Threadimport timedef work1():    nums.append(44)    print("----in work1---",nums)def work2():    #延時一會，保證t1線程中的事情做完    time.sleep(1)    print("----in work2---",nums)if __name__==‘__main__‘:    nums = [11, 22, 33]    t1 = Thread(target=work1)    t1.start()    t2 = Thread(target=work2)    t2.start()

 

結果都一樣：

 

 對於參數是字串，數字這種不可變類型的變數

 

，改變變數的值的時候，要用上global，否則程式報錯。

from threading import Threadimport timedef work1():    global nums    nums+1    print("----in work1---",nums)def work2():    #延時一會，保證t1線程中的事情做完    time.sleep(1)    print("----in work2---",nums)if __name__==‘__main__‘:    nums = 12    t1 = Thread(target=work1)    t1.start()    t2 = Thread(target=work2)    t2.start()

結果：

 

from threading import Threadimport timedef work1(nums):    nums=nums+1    print("----in work1---",nums)def work2(nums):    #延時一會，保證t1線程中的事情做完    time.sleep(1)    print("----in work2---",nums)if __name__==‘__main__‘:    g_nums = 11    t1 = Thread(target=work1, args=(g_nums,))     t1.start()    t2 = Thread(target=work2, args=(g_nums,))    t2.start()

結果：

 

 

 

from threading import Threadimport timedef work1(nums):    nums+1    print("----in work1---",nums)def work2(nums):    #延時一會，保證t1線程中的事情做完    time.sleep(1)    print("----in work2---",nums)if __name__==‘__main__‘:    g_nums = 11    t1 = Thread(target=work1, args=(g_nums,))     t1.start()    t2 = Thread(target=work2, args=(g_nums,))    t2.start()

結果：

 

python線程中的全域變數與局部變數