等待兩個子進程完成但不一定先等待

Question

我正在編寫一個程序，該程序創建兩個新進程，並且必須等待它們完成後才能繼續。如何啓動這兩個進程並讓程序等待兩者退出？考慮僞代碼：

我目前有：

create_process("program1.exe").wait() 
create_process("program2.exe").wait() 

這enificent作爲程序2可與程序1 concurently運行。

create_process("program1.exe") 
create_process("program2.exe").wait() 

這可能是錯誤的，因爲program1可能需要比program2更長的時間。

我對一個通用解決方案感興趣，我敢打賭有算法或設計模式發明處理這個東西。但是爲了給這個問題添加上下文，我正在編寫一個Python腳本，它會調用pgsql2shp.exe兩次，將兩個表從數據庫導出到本地機器，然後執行一個交集。這個腳本是用Python 2.7編寫的並且使用subprocess.popen

Answer 1

如何使用線程？ 如果啓動一對線程，每個線程都可以獨立運行，並且可以在線程完成時加入。

嘗試一些像這樣的代碼：（此代碼是大量註釋，這樣你可以遵循這是怎麼回事）

# Import threading 
import threading 

# Create a handler class. 
# Each instance will run in it's own independent thread 
class ThreadedHandler (threading.Thread): 

    # This method is called when you call threadInstance.start() 
    def run(self): 

     # Run your sub process and wait for it 
     # How you run your process is up to you 
     create_process(self.programName).wait() 

# Create a new thread object 
thread1 = ThreadedHandler() 

# Set your program name so that when the thread is started 
# the correct process is run 
thread1.programName = 'program1.exe' 

# Start the thread 
thread1.start() 

# Again, create a new thread object for the 2nd program 
thread2 = ThreadedHandler() 

# Set the program name 
thread2.programName = 'program2.exe' 

# Start the thread 
thread2.start() 

# At this point, each program is running independently in separate threads 
# Each thread will wait for their respective sub process to complete 

# Here, we join both threads. (Wait for both threads to complete) 
thread1.join() 
thread2.join() 

# When we get here, both of our programs are finished and they both ran in parallel