Parallel::ForkManage: 一个简单的并行进程用于fork管理:

Parallel::ForkManage: 一个简单的并行进程用于fork管理:  use Parallel::ForkManager;  my $pm = Parallel::ForkManager->new($MAX_PROCESSES);  DATA_LOOP:  foreach my $data (@all_data) {    # Forks and returns the pid for the child:    my $pid = $pm->start and next DATA_LOOP;    ... do some work with $data in the child process ...    $pm->finish; # Terminates the child process  }描述:这个模块是用于使用在并行操作中进行操作, 被fork的进程数量应该被限制。典型的使用是下载器从数百 数千个文件中检索代码用于下载器应该是这样的:  use LWP::Simple;  use Parallel::ForkManager;  ...  my @links=(    ["http://www.foo.bar/rulez.data","rulez_data.txt"],    ["http://new.host/more_data.doc","more_data.doc"],    ...  );  ...  # Max 30 processes for parallel download  my $pm = Parallel::ForkManager->new(30);  LINKS:  foreach my $linkarray (@links) {    $pm->start and next LINKS; # do the fork    my ($link, $fn) = @$linkarray;    warn "Cannot get $fn from $link"      if getstore($link, $fn) != RC_OK;    $pm->finish; # do the exit in the child process  }  $pm->wait_all_children;DESCRIPTION ：这个模块用于在并行操作中进程操作,fork的进程数应该被限制。典型的使用一个下载器来检索成百/上千个文件。  use LWP::Simple;  use Parallel::ForkManager;  ...  my @links=(    ["http://www.foo.bar/rulez.data","rulez_data.txt"],    ["http://new.host/more_data.doc","more_data.doc"],    ...  );  ...  # Max 30 processes for parallel download  my $pm = Parallel::ForkManager->new(30);  LINKS:  foreach my $linkarray (@links) {    $pm->start and next LINKS; # do the fork    my ($link, $fn) = @$linkarray;    warn "Cannot get $fn from $link"      if getstore($link, $fn) != RC_OK;    $pm->finish; # do the exit in the child process  }  $pm->wait_all_children;首先你需要实例化ForkManager  使用"new"构造器。你必须指定创建的最大进程数。 如果你指定为0,然后不进行fork，这对调试是有好处下一步,使用$pm->start  来fork.$pm 返回0对于child process, 和child pid 对于parent process "and next" 跳过内部循环在parent process.  NOTE: $pm->start dies if the fork fails.  $pm->finish 中断child process  注意:你不能使用$pm->start  如果你已经在child process里。  如果你需要管理另外的子进程集在child process,  你必须实例化另外一个 Parallel::ForkManager对象。   METHODS :  注释的字母表明方法允许在哪里 P对于parent C对child   new $processes： 实例化一个新的 Parallel::ForkManager object.你必须指定0（zero), 然后no children 会被forked.这是用于调试目的。第2个参数,$tempdir, 是只能用于如果你要children 发回一个引用到一些数据。如果没有提供,它是设置通过调用 File::Temp::tempdir().new方法会die如果 temporary directory 不存在或者它不是一个目录start [ $process_identifier ]这个方法开始fork, 它返回child process的pid 对于父进程0对于子进程。如果$processes 参数对于构造器是0,那么假设你是在child process,$pm->start simply returns 0.一个可选的$process_identifier 可以被提供用于这个方法,它是通过run_on_finish使用finish [ $exit_code [, $data_structure_reference] ] 关闭 child 进程通过退出和接收一个可选的exit code（默认code是0）可以通过回调在父进程中检索如果第2个参数提供,child 尝试发送它的内容到parent.set_max_procs $processes允许你设置一个新的最大的children数量wait_all_children:你可以调用这个方法来等待所有的被fork的进程,这是一个堵塞等待:reap_finished_children:这是一个非堵塞请求来收割children，执行回调独立于调用"start"或者"wait_all_children". is_parent返回真如果在parent里 返回false在child里:  $pm->wait_all_children;  print "22222222222222222222222222\n";  print $pm->is_parent;  print "\n";  print "22222222222222222222222222\n";22222222222222222222222222122222222222222222222222222[oracle@node01 bb]$ max_procs：返回奖fork的最大进程数  $pm->wait_all_children;  print "22222222222222222222222222\n";  print $pm->is_parent;  print "\n";  print $pm->max_procs;  print "\n";  print "22222222222222222222222222\n";2222222222222222222222222213022222222222222222222222222running_procs返回 forked 进程pids 当前被Parallel::ForkManager监控的。注意 children 是仍旧被汇报为运行的直到 fork manager收割它们，通过next call 来start或者wait_all_children。[oracle@node01 bb]$ ps -ef | grep t1.ploracle   11066  1970  3 06:42 pts/0    00:00:00 perl t1.ploracle   11068 11066  0 06:42 pts/0    00:00:00 perl t1.ploracle   11069 11066  0 06:42 pts/0    00:00:00 perl t1.ploracle   11070 11066  0 06:42 pts/0    00:00:00 perl t1.ploracle   11071 11066  0 06:42 pts/0    00:00:00 perl t1.ploracle   11072 11066  0 06:42 pts/0    00:00:00 perl t1.ploracle   11074  2278  0 06:42 pts/1    00:00:00 grep t1.pl1106711068110711107011069$a====8wait_for_available_procs( $n ):等待直到$n 可用进程sots 是可用的,如果$n 没有给定 默认是1CALLBACKS   回调:你可以定义回调在代码里, 被调用在事件像 开始一个进程或者当finish的时候。调用可以定义下面的方法:run_on_finish $code [, $pid ]你可以定义一个子例程, 当一个child 是被终止时被调用 它是在父进程中调用:$code 的参数如下: - pid of the process, which is terminated  - exit code of the program  - identification of the process (if provided in the "start" method)  - exit signal (0-127: signal name)  - core dump (1 if there was core dump at exit)  - datastructure reference or undef (see RETRIEVING DATASTRUCTURES)run_on_start $code你可以定义一个子例程当一个child 启动时调用,它调用在一个child 的成功启动在parent 进程$code的参数如下:这个$code的参数如下:  - pid of the process which has been started  - identification of the process (if provided in the "start" method)你可以定义一个子例程,当child process 需要等待startup时被调用。如果 $period没有被定义,然后一个调用时完成对于每个child.如果 $period是被定义,然后$code 是被周期性的调用。module 等待$period 数秒在两个请求之间,BLOCKING CALLS当它等待child processes终止,Parallel::ForkManager 是在一个fork和一个hard place(如果你excuse the terrible pun)底层Perl waitpid 函数 模块依赖可以堵塞直到任何一个指定的或者任何child process 终止这意味着module 可以做两件事情中的一个 当它等待其中一个child processes终止:只等待它自己的child processes:并行get:这个小的例子可以用于get URLs并行的:[oracle@node01 cc]$ time perl a1.pl $c====Parallel::ForkManager$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/1 5.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/5 9.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/4 8.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/3 7.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/2757485/3 3.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/2757485/1 1.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/7 11.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/8 12.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/9 13.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/6 10.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/1756685/2 6.txt$linkarray=== http://blog.csdn.net/zhaoyangjian724/article/category/2757485/2 2.txtreal0m8.121suser0m0.939ssys0m0.452s use LWP::Simple; use Parallel::ForkManager;  my @links=(    ["http://blog.csdn.net/zhaoyangjian724/article/category/2757485/1","1.txt"],    ["http://blog.csdn.net/zhaoyangjian724/article/category/2757485/2","2.txt"],    ["http://blog.csdn.net/zhaoyangjian724/article/category/2757485/3","3.txt"],    ["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/1","5.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/2","6.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/3","7.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/4","8.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/5","9.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/6","10.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/7","11.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/8","12.txt"],["http://blog.csdn.net/zhaoyangjian724/article/category/1756685/9","13.txt"]  );sub getsrore{  my $link=shift;  my $fn=shift;  open fh1,">$fn" || die "open csdn file failed:$!";   my $ua = LWP::UserAgent->new;  $ua->timeout(10);  $ua->env_proxy;  $ua->agent("Mozilla/8.0");  my $response = $ua->get("$link");  print fh1  $response->content;    close fh1;    };    # Max 30 processes for parallel download  my $pm = Parallel::ForkManager->new(30);  LINKS:  foreach my $linkarray (@links) {    $pm->start and next LINKS; # do the fork    print "\$linkarray=== @$linkarray\n";    my ($link, $fn) = @$linkarray;      &getstore($link, $fn);     $pm->finish; # do the exit in the child process  }  $pm->wait_all_children;Callbacks：使用回调程序的例子得到child exit codes： use strict;  use Parallel::ForkManager;  my $max_procs = 5;  my @names = qw( Fred Jim Lily Steve Jessica Bob Dave Christine Rico Sara );  # hash to resolve PID's back to child specific information  my $pm = Parallel::ForkManager->new($max_procs);  # Setup a callback for when a child finishes up so we can  # get it's exit code  $pm->run_on_finish( sub {      my ($pid, $exit_code, $ident) = @_;      print "** $ident just got out of the pool ".        "with PID $pid and exit code: $exit_code\n";  });  $pm->run_on_start( sub {      my ($pid, $ident)=@_;      print "** $ident started, pid: $pid\n";  });  $pm->run_on_wait( sub {      print "** Have to wait for one children ...\n"    },    0.5  );  NAMES:  foreach my $child ( 0 .. $#names ) {    my $pid = $pm->start($names[$child]) and next NAMES;    # This code is the child process    print "This is $names[$child], Child number $child\n";    sleep ( 2 * $child );    print "$names[$child], Child $child is about to get out...\n";    sleep 1;    $pm->finish($child); # pass an exit code to finish  }  print "Waiting for Children...\n";  $pm->wait_all_children;  print "Everybody is out of the pool!\n";