并发附加到使用Perl的同一个文件

下面是一个示例程序,从典型的前沿开始：

#! /usr/bin/perl

use warnings;
use strict;

use Fcntl qw/ :flock /;

然后我们指定日志的路径和将运行的客户端的数量：

my $log = "/tmp/my.log";
my $clients = 10;

要记录消息,请以附加模式打开文件,以便所有写入都会自动结束.然后调用鸡群等待我们的独家访问日志.一旦我们起床,写信息并关闭手柄,自动释放锁.

sub log_step {
  my($msg) = @_;

  open my $fh,">>",$log or die  "$0 [$$]: open: $!";
  flock $fh,LOCK_EX      or die  "$0 [$$]: flock: $!";
  print $fh "$msgn"      or die  "$0 [$$]: write: $!";
  close $fh               or warn "$0 [$$]: close: $!";
}

现在fork $客户端子进程通过三个步骤之间的随机间隔：

my %kids;
my $id = "A";
for (1 .. $clients) {
  my $pid = fork;
  die "$0: fork: $!" unless defined $pid;

  if ($pid) {
    ++$kids{$pid};
    print "$0: forked $pidn";
  }
  else {
    my $user = "User" . $id;
    log_step "$user: Step 1";
    sleep rand 3;
    log_step "$user: Step 2";
    sleep rand 3;
    log_step "$user: Step 3";
    exit 0;
  }

  ++$id;
}

不要忘记等待所有的孩子退出：

print "$0: reaping children...n";
while (keys %kids) {
  my $pid = waitpid -1,0;
  last if $pid == -1;

  warn "$0: unexpected kid $pid" unless $kids{$pid};
  delete $kids{$pid};
}

warn "$0: still running: ",join("," => keys %kids),"n"
  if keys %kids;

print "$0: done!n",`cat $log`;

样品输出：

[...]
./prog.pl: reaping children...
./prog.pl: done!
UserA: Step 1
UserB: Step 1
UserC: Step 1
UserC: Step 2
UserC: Step 3
UserD: Step 1
UserE: Step 1
UserF: Step 1
UserG: Step 1
UserH: Step 1
UserI: Step 1
UserJ: Step 1
UserD: Step 2
UserD: Step 3
UserF: Step 2
UserG: Step 2
UserH: Step 2
UserI: Step 2
UserI: Step 3
UserB: Step 2
UserA: Step 2
UserA: Step 3
UserE: Step 2
UserF: Step 3
UserG: Step 3
UserJ: Step 2
UserJ: Step 3
UserE: Step 3
UserH: Step 3
UserB: Step 3

请记住,订单将与运行不同.