perl实现多进程的操作

场景： 我们需要访问若干机器进行状态检查，文件拷贝之类的操作。

分析：我们可以使用循环的方式来进行逐个操作。如果每个操作耗时很短的话还可以接受。假如每个操作耗时很长，这样单个处理的方式就显得效率低下。因为每个节点的操作是相互独立的，我们可以使用多进程的方式并行处理。为了防止本地机器的资源耗费很大，我们又期望对并行的个数进行限制。在操作过程中，还可能出现操作卡住的情况，因此我们还需要限制操作的时间，如果超过这个限定的时间之后我们就认为操作失败，可能需要人工干预。

实现： 基于上述描述，我们可以用perl来实现上述功能。

use warnings;
use strict;
use File::Spec;
use FindBin qw($Bin);
use Net::OpenSSH;
use POSIX ":sys_wait_h";


#限制同时操作的节点数目
my $host_number_simultaneity = 6;
#设置操作的最大时间
my $install_seconds_limiation = 1800;
#机器的登陆用户名和密码
my $login_user = "root";
my $login_passwd = "312";
my $ssh_ops = {user => $login_user, password => $login_passwd, master_opts => [-o => "UserKnownHostsFile=/dev/null", -o => "StrictHostKeyChecking=no"]};

#当前目录下记录操作的日志文件
my $log_file='install.log';
open(LOG_FILENAME, '>', "$log_file") || die "\nCan't open log file $log_file to record results of opeation !! ";
select LOG_FILENAME;
$| = 1;

chomp(my $time_stamp=`date`);
print "step 0: operation begin at $time_stamp\n";

#获取操作节点的IP地址，用户这里可以自行处理
my @all_host_ip = qw/192.168.10.10 192.168.10.12 192.168.10.14/;
say LOG_FILENAME "all the hosts ip are as follows: @all_host_ip";

my $host_number_total = @all_host_ip;
my $host_number_ongoing = 0;
my $host_number_finished = 0;
my $host_number_timeout = 0;
# (key : pid, value : host ip)
my %pid_to_host = ();
# (key : pid, value : start time-seconds)
my %pid_to_start_time = ();

$SIG{CHLD} = sub{$host_number_ongoing--};

say LOG_FILENAME "there are $host_number_total hosts in all";
for (my $index=0; $index<$host_number_total;$index++) {
    my $pid = fork();
    if ( !defined($pid) ) {
        say LOG_FILENAME "Error in fork: $!. This is going to deal with host $all_host_ip[$index]";
        print "Error in fork: $!. This is going to deal with host $all_host_ip[$index]\n";
        exit 1;
    }
    if ( $pid == 0 ) {
        say LOG_FILENAME "index: $index -- This is going to begin operation on host $all_host_ip[$index]";
        print "index: $index -- This is going to begin operation on host $all_host_ip[$index]\n";
        #对每个节点进行操作处理
        &operation_host($all_host_ip[$index]);
        say LOG_FILENAME "index: $index -- This is the end of installation on host $all_host_ip[$index]";
        exit 0;
    }

    $pid_to_host{$pid} = $all_host_ip[$index];
    $pid_to_start_time{$pid} = time;
    $host_number_ongoing++;

    #如果正在操作的节点数量超过限制的数量，就等待30秒，再检查是否有操作完毕
    while ( $host_number_ongoing >= $host_number_simultaneity ) {
        sleep(30);
    }   
}

my $collect_pid;
while ( ($host_number_finished+$host_number_timeout) != $host_number_total ) {
    if ( ($collect_pid = waitpid(-1,WNOHANG)) > 0 ) {
        #操作结束之后，从哈希中将记录删除
        $host_number_finished++;
        chomp($time_stamp=`date`);
        say LOG_FILENAME "operation on host $pid_to_host{$collect_pid} finished at $time_stamp ";
        if ( exists $pid_to_host{$collect_pid} ) {
            delete $pid_to_host{$collect_pid};
        }
        if ( exists $pid_to_start_time{$collect_pid} ) {
            delete $pid_to_start_time{$collect_pid};
        }
    }

    #检查没有结束的操作是否超时
    my $current_time = time;
    $host_number_timeout = 0;
    while ( my ($key, $value) = each %pid_to_start_time ) {
        if ( ($current_time - $pid_to_start_time{$key}) >= $install_seconds_limiation ) {
            say LOG_FILENAME "operation on host $pid_to_host{$key} are time out yet";
            $host_number_timeout++;
        }
    }

    chomp($time_stamp=`date`);
    say LOG_FILENAME "sleep 30s to check again...current time: $time_stamp";
    print "sleep 30s to check again...current time: $time_stamp\n";
    sleep(30);
}

# 将超时的节点ip信息打印处理
if ( $host_number_total > 0 ) {
    while ( my ($key, $value) = each %pid_to_host ) {
        say LOG_FILENAME "operation on host $pid_to_host{$key} are time out finally!!";
        print "operation on host $pid_to_host{$key} are time out finally!!\n";
    }
}

close LOG_FILENAME;
exit 0;