首页 \ 问答 \ 我如何知道Fork和Join在Java中的池大小是否足够？(How do I know if Fork and Join has enough pool size in Java?)

我如何知道Fork和Join在Java中的池大小是否足够？(How do I know if Fork and Join has enough pool size in Java?)

 我正试图对一些大数据实施分而治之的解决方案。 我使用fork和join来把事情分解成线程。 不过，我有一个关于fork机制的问题：如果我将分而治之条件设置为：  
@Override
protected SomeClass compute(){
    if (list.size()<LIMIT){
        //Do something here
        ...
    }else{
        //Divide the list and invoke sub-threads
        SomeRecursiveTaskClass subWorker1 = new SomeRecursiveTaskClass(list.subList());
        SomeRecursiveTaskClass subWorker2 = new SomeRecursiveTaskClass(list.subList());
        invokeAll(subWorker1, subWorker2);
        ...
    }
}
 
 如果没有足够的资源调用subWorker会发生什么（例如池中没有足够的线程）？ Fork / Join框架是否为可用线程维护池大小？ 还是应该将这个条件加入我的分而治之逻辑？ 

I am trying to implement a divide-and-conquer solution to some large data. I use fork and join to break down things into threads. However I have a question regarding the fork mechanism: if I set my divide and conquer condition as: 
@Override
protected SomeClass compute(){
    if (list.size()<LIMIT){
        //Do something here
        ...
    }else{
        //Divide the list and invoke sub-threads
        SomeRecursiveTaskClass subWorker1 = new SomeRecursiveTaskClass(list.subList());
        SomeRecursiveTaskClass subWorker2 = new SomeRecursiveTaskClass(list.subList());
        invokeAll(subWorker1, subWorker2);
        ...
    }
}
 
What will happen if there is not enough resource to invoke subWorker (e.g. not enough thread in pool)? Does Fork/Join framework maintains a pool size for available threads? Or should I add this condition into my divide-and-conquer logic? 

原文：https://stackoverflow.com/questions/48157596

更新时间：2023-08-17 09:08

最满意答案

 此功能已从版本5中的Rails中删除，具有以下理由：  
 
  ...根据我们的经验，应用程序不使用doc：app生成API ...如果团队绝对需要为内部目的生成应用程序文档，他们仍然可以轻松编写自己的任务...  
 
 通过在/lib/tasks/documentation.rake中创建一个文件，可以轻松恢复该功能，其中包含以下内容，取自官方任务的最新版本 ：  
# /lib/tasks/documentation.rake
require 'rdoc/task'

namespace :doc do
  RDoc::Task.new("app") { |rdoc|
    rdoc.rdoc_dir = 'doc/app'
    rdoc.template = ENV['template'] if ENV['template']
    rdoc.title = ENV['title'] || 'Rails Application Documentation'
    rdoc.options << '--line-numbers'
    rdoc.options << '--charset' << 'utf-8'
    rdoc.rdoc_files.include('README.md')
    rdoc.rdoc_files.include('app/**/*.rb')
    rdoc.rdoc_files.include('lib/**/*.rb')
  }
  Rake::Task['doc:app'].comment = "Generate docs for the app -- also available doc:rails, doc:guides (options: TEMPLATE=/rdoc-template.rb, TITLE=\"Custom Title\")"
end
 
 虽然，在这一点上，从命令行运行这样的东西似乎更容易：  
rdoc --main README.md --title 'My Fancy Title' README.md app/**/*.rb lib/**/*.rb 

This functionality was removed from Rails in version 5 with the following justification: 
 
 ...In our experience applications do not generate APIs using doc:app...If a team absolutely needs to generate application documentation for internal purposes, they can still easily write their own task... 
 
The functionality can be easily restored by creating a file at /lib/tasks/documentation.rake with the following contents, taken from the last version of the official task: 
# /lib/tasks/documentation.rake
require 'rdoc/task'

namespace :doc do
  RDoc::Task.new("app") { |rdoc|
    rdoc.rdoc_dir = 'doc/app'
    rdoc.template = ENV['template'] if ENV['template']
    rdoc.title = ENV['title'] || 'Rails Application Documentation'
    rdoc.options << '--line-numbers'
    rdoc.options << '--charset' << 'utf-8'
    rdoc.rdoc_files.include('README.md')
    rdoc.rdoc_files.include('app/**/*.rb')
    rdoc.rdoc_files.include('lib/**/*.rb')
  }
  Rake::Task['doc:app'].comment = "Generate docs for the app -- also available doc:rails, doc:guides (options: TEMPLATE=/rdoc-template.rb, TITLE=\"Custom Title\")"
end
 
Although, at this point it almost seems easier to just run something like this, from the command line: 
rdoc --main README.md --title 'My Fancy Title' README.md app/**/*.rb lib/**/*.rb

我如何知道Fork和Join在Java中的池大小是否足够？(How do I know if Fork and Join has enough pool size in Java?)

最满意答案

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