線程的參數

Question

我想傳遞值的列表，讓每個人通過了作爲一個獨立的線程列表上：

例如：

import time 
import threading 

list_args = [arg1, arg2, arg3, ...., argn] 

# Code to execute in an independent thread 
import time 
def countdown(n): 
    while n > 0: 
     print('T-minus', n) 
     n -= 1 
     time.sleep(0.5) 


# Create and launch a thread 
t1 = threading.Thread(target=countdown, args=(arg1,)) 
t2 = threading.Thread(target=countdown, args=(arg2,)) 
. 
. 
. 
tn = threading.Thread(target=countdown, args=(argn,)) 
t1.start(); t2.start(); tn.start() 

Answer 1

快速修復

致電.join()對您的每個t1，t2等線程結束。

詳細

我懷疑你的真正的問題是「爲什麼不countdown被稱爲？」 Thread.join()方法會導致主線程在繼續之前等待其他線程完成執行。沒有它，一旦主線程完成，它就會終止整個過程。

在你的程序中，當主線程完成執行時，在進程調用它們的countdown函數之前，進程將與其所有線程一起被終止。

其他問題：

1. 它最好包括minimum working example。你的代碼不能像寫入那樣執行。

2. 通常使用某種數據結構來管理線程。這很好，因爲它使得代碼更加緊湊，通用且可重用。

3. 您無需兩次導入time。

這可能是接近你想要什麼：

import time 
import threading 

list_args = [1,2,3] 

def countdown(n): 
    while n > 0: 
     print('T-minus', n) 
     n -= 1 
     time.sleep(0.5) 


# Create and launch a thread 
threads = [] 
for arg in list_args: 
    t = threading.Thread(target=countdown,args=(arg,)) 
    t.start() 
    threads.append(t) 

for thread in threads: 
    thread.join() 

Answer 2

import time 
import threading 

list_args = [10, 9, 8, 7, 6, 5, 4, 3, 2, 1] 

# Code to execute in an independent thread 
def countdown(n): 
    while n > 0: 
     print('T-minus', n) 
     n -= 1 
     time.sleep(0.5) 


# Create and launch a thread 
for item in list_args: 
    thread = threading.Thread(target=countdown, args=(item,)) 
    thread.start() 

Answer 3

我認爲這會做你描述：

for a in list_args: 
    threading.Thread(target=countdown, args=(a,)).start() 

Answer 4

可以將所有的線程添加到列表與參數的數量無關。在主程序結束時，您必須加入所有主題。否則主線程退出並終止所有其他線程。

工作代碼：

import time 
import threading 

# create list [0, 1, ..., 9] as argument list 
list_args = range(10) 

# Code to execute in an independent thread 
def countdown(n): 
    while n > 0: 
     print('T-minus', n) 
     n -= 1 
     time.sleep(0.5) 

if __name__ == '__main__': 
    threads = [] 

    # create threads 
    for arg in list_args: 
     threads.append(threading.Thread(target=countdown, args=(arg,))) 

    # start threads 
    for thread in threads: 
     print("start") 
     thread.start() 

    # join threads (let main thread wait until all other threads ended) 
    for thread in threads: 
     thread.join() 

    print("finished!")