Question

我需要执行只能由主进程执行的操作。奴隶们无法做任何事情，只能等待主人完成。因此，我做了以下（伪代码，我包装了大多数例程，所以我很难想出实际的MPI代码。我希望这些评论在解释我在做什么时已经足够清楚了）

def routine():

    if not isMaster(): 
        # I am a slave. I just sit here, waiting for the master to finish.
        # wait for a string from the master explaining the state
        string = MPI_Bcast("whatever", 0) 
        return (string == "SUCCESS")

    <master does its long running business>

    string = MPI_Bcast("SUCCESS", 0) # tell the slaves it worked fine.

    return True

这是否有效，还是我滥用广播？

Answer 1

如果你制作那个伪代码：

def routine():

    if not isMaster(): 
        # I am a slave. I just sit here, waiting for the master to finish.
        # wait for a string from the master explaining the state
        string = MPI_Bcast("whatever", 0) 
        return (string == "SUCCESS")

    else:
        <master does its long running business>
        string = MPI_Bcast("SUCCESS", 0) # tell the slaves it worked fine.

    return True

然后你应该没事。（当然，您需要确保为您的语言提供特定的MPI API。）通常，对于广播或任何集体操作，通信器中的每个等级都需要执行相同数量的呼叫。为了理解，以一种无条件地在同一源代码行上为每个等级执行Bcast的方式重构程序可能是有益的，例如。

def routine():
    status_code = UNKNOWN
    if isMaster(): 
        #do stuff
        status_code = OK

    MPI_Bcast(&status_code, 0)
    #check status_code on each rank

我可以使用MPI_Bcast进行同步吗？

1 个答案: