如何使 Perl 的 File::Find 更快?

问题描述：

我有一个名为 Lib 的文件夹，我正在使用 File::Find 模块在整个目录中搜索该文件夹，例如 D:\.搜索需要很长时间，如果驱动器有很多子目录，甚至需要 5 分钟.如何更快地搜索该 Lib，以便在几秒钟内完成?

I have a folder named Lib and I am using the File::Find module to search that folder in whole dir say, D:\. It's taking a long time to search, say even 5 mins if the drive has a lot of subdirectories. How can I search that Lib faster so it will be done in seconds?

我的代码如下所示:

    find( \&Lib_files, $dir);
    sub Lib_files
    {
       return unless -d;
      if ($_=~m/^([L|l]ib(.*))/)
      {
          print"$_";
      }
      return;
    }

答

在没有预先存在的索引的情况下搜索文件系统是 IO 绑定的.否则，产品范围从 locate 到 Windows 桌面搜索将不存在.

Searching the file system without a preexisting index is IO bound. Otherwise, products ranging from locate to Windows Desktop Search would not exist.

输入 D:\>目录/b/s >directory.lst 并观察该命令运行所需的时间.如果不首先索引文件，您不应该期望击败它.

Type D:\> dir /b/s > directory.lst and observe how long it takes for that command to run. You should not expect to beat that without indexing files first.

您可以做出的一项重大改进是减少打印频率.一个小改进是，如果您不打算捕获，则不要使用捕获括号:

One major improvement you can make is to print less often. A minor improvement is not to use capturing parentheses if you are not going to capture:

my @dirs;

sub Lib_files {
   return unless -d $File::Find::name; 
   if ( /^[Ll]ib/ ) {
        push @dirs, $File::Find::name;
   }
   return;
}

在我的系统上，一个简单的脚本使用 File::Find 打印我的主目录下所有子目录的名称，大约有 150,000 个文件，与 dir % 相比，运行需要几分钟时间首页%/ad/b/s >dir.lst 在大约 20 秒内完成.

On my system, a simple script using File::Find to print the names of all subdirectories under my home directory with about 150,000 files takes a few minutes to run compared to dir %HOME% /ad/b/s > dir.lst which completes in about 20 seconds.

我倾向于使用:

use File::Basename;

my @dirs = grep { fileparse($_) =~ /^[Ll]ib/ }
           split /\n/,  `dir %HOME% /ad/b/s`;

在我的系统上在 15 秒内完成.

which completed in under 15 seconds on my system.

如果%PATH%中还有其他dir.exe，cmd.exe的内置dir 不会被调用.您可以使用 qx!cmd.exe/c dir %HOME%/ad/b/s ! 以确保调用正确的 dir.

If there is a chance there is some other dir.exe in %PATH%, cmd.exe's built-in dir will not be invoked. You can use qx! cmd.exe /c dir %HOME% /ad/b/s ! to make sure that the right dir is invoked.

如何使 Perl 的 File::Find 更快?

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