初学者提问：多进程的问题，谢谢高手解答~~~

honckly

是么。。。
为啥我这里不退出呢。。。
光标一直闪。。。

dahe_1984

#!/usr/bin/perl
# test_proc_3.pl
# test multi process
# create by lianming: 2009-08-12
use strict;
use warnings;
use POSIX ":sys_wait_h";
## == number of proc ==
my $num_proc = 0;
my @proc;
## == number of collected ==
my $num_collect = 0;
my $collect;
## == get the child signal ==
$SIG{CHLD} = sub { $num_proc-- };
for (my $i = 0; $i < 10; $i ++) {
    ## == fork a new process ==
    my $pid = fork();
    if (!defined($pid)) {
        print "Error in fork: $!";
        exit 1;
    }
    if ($pid == 0) {
        ## == child proc ==
        print "Child $i : My pid = $$\n";
        sleep(5);
        print "Child $i : end\n";
        exit 0;
    } else {
#
# 父进程和子进程是一起生成的
#
        push(@proc, $pid);  
    }

#
#    注释的部分你知道在做什么呢？
#
#    $num_proc ++;
#    ## == if need to collect zombies ==
#    if (($i-$num_proc-$num_collect) > 0) {
#        while (($collect = waitpid(-1, WNOHANG)) > 0) {
#            $num_collect ++;
#        }
#    }
#    do {
#        sleep(1);
#    } until ($num_proc < 3);
}

#
# 先fork，让所有的子进程全部启动，然后在等所有的进程全部结束
#
foreach (@proc) {
    waitpid($_, 0);
}
   
exit 0;



------------------------注意看时间---------------------------------------------------------------
time perl test.pl
Child 0 : My pid = 21331
Child 1 : My pid = 21333
Child 2 : My pid = 21334
Child 3 : My pid = 21335
Child 4 : My pid = 21336
Child 5 : My pid = 21337
Child 6 : My pid = 21338
Child 7 : My pid = 21339
Child 8 : My pid = 21340
Child 9 : My pid = 21341
Child 0 : end
Child 1 : end
Child 3 : end
Child 2 : end
Child 4 : end
Child 5 : end
Child 6 : end
Child 7 : end
Child 9 : end
Child 8 : end

real    0m5.027s
user    0m0.015s
sys     0m0.012s
--------------------------------------------------------

--------------------以前的版本没有达到多进程节省时间的效果---------------------------------------
time perl test.pl
Child 0 : My pid = 21411
Child 1 : My pid = 21412
Child 2 : My pid = 21413
Child 0 : end
Child 3 : My pid = 21418
Child 1 : end
Child 4 : My pid = 21419
Child 2 : end
Child 5 : My pid = 21420
Child 3 : end
Child 6 : My pid = 21421
Child 4 : end
Child 7 : My pid = 21422
Child 5 : end
Child 8 : My pid = 21423
Child 6 : end
Child 9 : My pid = 21428
Child 7 : end
Child 8 : end
Child 9 : end

real    0m20.029s
user    0m0.016s
sys     0m0.012s
------------------------------------------------------------------------------

toniz

大丈夫当持三尺剑，杀尽天下贪官八百万，流血三千里，奈何在写perl