[PerlChina] Re: 父子进程间变量共享

之前一直没有用过DB_File,不太熟。用多线程的策略写了一段代码。所有线程结束后，打印%hash,仍然为空。请帮我看看，问题出在那？

=========================================================================

[linhy@genome2 BatchPrimer3.extension]$ less multithread.pl

#! /usr/bin/perl
use warnings;
use strict;
use Thread qw(:DEFAULT );

 

my @task = (1..8) ; #8个任务

 

my (%hash1 , %hash2);
my @threadArray ;

 

foreach my $thread (@task){
  sleep 1;

  

 # 同时最多有3个线程
  if (@threadArray >= 3){
    my $oldestThread = shift @threadArray ;
    $oldestThread->join() ;
  }

 

  #新线程由此开始
  my $newThread = Thread->new(\&start_thread,  $thread);
  push (@threadArray, $newThread);
}

 

#等待所有线程结束

while (my $livethread = shift @threadArray){
  $livethread->join();
}

 

#打印hash
print "===hash 1====\n";
while (my ($key, $value) = each %hash1){
  print "hash1: $key\t$value\n";
}
print "===hash 2====\n";
while (my ($key, $value) = each %hash2){
  print "hash1: $key\t$value\n";
}

exit;

 

sub start_thread{

 

  my ( $thread) = @_ ;
  print "Start Thread for $thread\n";
  $hash1{$thread} = 'a'.$thread ;
  $hash2{$thread} = 'b'.$thread ;
  sleep 5 ;
  return;
}

=======================================================================

 

运行显示：

 

[linhy@genome2 BatchPrimer3.extension]$ perl multithread.pl
Start Thread for 1
Start Thread for 2
Start Thread for 3
Start Thread for 4
Start Thread for 5
Start Thread for 6
Start Thread for 7
Start Thread for 8
===hash 1====
===hash 2====
[linhy@genome2 BatchPrimer3.extension]$ less multithread.pl

 

----- Original Message -----

From: "Yonghua (Jeff)" <yonghua.peng@gmail.com>

To: <perlchina@googlegroups.com>

Sent: Wednesday, August 19, 2009 2:26 PM

Subject: [PerlChina] Re: 父子进程间变量共享

> 2009/8/19 liseen <liseen.wan@gmail.com>:
>> fork 之后各个进程的内存并不是共享的， 怎么能用这个方法呢， 呵呵。
>>
>>
>> 2009/8/19 Haiyan Lin <linhy0120@gmail.com>
>>>
>>> 能不能具体一点，在楼顶的代码中加点示例代码。谢谢。
>>>
>
>
> 其实看看模块的文档很容易搞的。
> 简单写个测试脚本仅供参考：
>
> use strict;
> use warnings;
> use DB_File;
>
>
> if ( fork ) {  # in parent
>    for (1..30) {
>         increase();
>         sleep 1;
>     }
>
> } else { # in child
>    for (1..30) {
>         sleep 1;
>         my %hash;
>         tie %hash, "DB_File", "a.db", O_RDONLY, 0444, $DB_HASH
>             or die "tie dbfile failed: $!\n";
>         print $hash{'test'},"\n";
>         untie %hash;
>     }
> }
>
> sub increase {
>    my %hash;
>
>    tie %hash, "DB_File", "a.db", O_RDWR|O_CREAT, 0666, $DB_HASH
>        or die "tie dbfile failed: $!\n";
>
>    $hash{'test'} ++;
>    untie %hash;
> }
>
>
>
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