在Perl中，如何阻止一堆系统调用才能完成? [英] In Perl, how can I block for a bunch of system calls to finish?

问题描述

我正在做一堆我想并行运行的系统调用:

I'm doing a bunch of system calls that I want to run in parallel:

system(" sleep 5 && echo step 1 done &");
system(" sleep 3 && echo step 2 done &");
system(" sleep 7 && echo step 3 done &");

// block here

如何阻止程序流，直到所有系统调用完成?

How can I block the program flow until all the system calls are finished?

推荐答案

最简单的方法可能是为每个系统调用fork一个新的子进程，然后等待它们完成.这是一个简化的示例:

The easiest way to do this is probably to fork a new child process for each system call, and then wait for them to finish. Here's a simplified example:

my @commands = ( "sleep 5 && echo step 1 done",
                 "sleep 3 && echo step 2 done",
                 "sleep 7 && echo step 3 done" );

my @pids;
foreach my $cmd( @commands ) {
    my $pid = fork;
    if ( $pid ) {
        # parent process
        push @pids, $pid;
        next;
    }

    # now we're in the child
    system( $cmd );
    exit;            # terminate the child
}

wait for @pids;   # wait for each child to terminate

print "all done.\n";

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