Issue #6694 has been updated by headius (Charles Nutter).


I will comment on stack sizing on the other issue.

As far as passing params and not starting the thread, it doesn't seem like a bad API. There are other thread characteristics that could be passed at construction time like abort_on_exception, priority, and potentially things like "start" (to autostart as the current API), "daemon" to create threads that will keep the VM alive after main thread exits, and so on.

FWIW, JVM threads do not run until explicitly started. The start of the actual native thread is deferred until Thread#start is called. Thread-runtime operations raise exceptions if called before the thread is started. Simple enough.


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Feature #6694: Thread.new without block.
https://bugs.ruby-lang.org/issues/6694#change-28238

Author: ko1 (Koichi Sasada)
Status: Assigned
Priority: Normal
Assignee: ko1 (Koichi Sasada)
Category: core
Target version: 2.0.0


=begin
= Abstract

Support Thread.new() without block.

Before: Thread.new(params...){|thread_local_params| ...}

After: Thread.new(proc: lambda{|tl_params...| ...}, args: params..., other_thread_config...)

= Background

Thread.new creates new Thread object and run passed block in another thread immediately.  Thread.new can receive parameters and pass all parameters to block.

  Thread.new(a, b, c) do |ta, tb, tc|
    # ta, tb, tc is thread local
  }

There are some request to specify thread configurations such as stack size described in [Ruby 1.9 - Feature #3187] (in this case, stack size for Fiber.new).  However, we have no way to pass such thread configuration on the Thread.new().

= Proposal

Allow Thread.new() without block.  A block will be passed with proc parameter.  Passed arguments will be passed with args parameter.

  # ex1
  Thread.new(){...}
  #=>
  Thread.new(proc: -> {...})
  
  # ex2
  Thread.new(a, b, c){|ta, tb, tc| ...}
  #=>
  Thread.new(proc: ->(ta, tb, tc){ ... }, params: [a, b, c])

If you want to specify stack size, then:

  Thread.new(stack_size: 4096, proc: proc{...}, args: [a, b, c])

Note that I'll make another ticket for thread (and fiber) creation parameters.

This change can be described with the following pseudo code:

  def Thread.new(*args, &block)
    if block
      Thread.new_orig(*args, &block)
    else
      config = args[0] || raise ArgumentError
      stack_size = config[:stack_size]
      # ... and process another parameters 
      Thread.new_orig(*config[:args], &config[:proc])
    end
  end

= Another proposal

On the [ruby-core:43385], Nahi-san proposed that if no block given on Thread.new(), then create "waiting" thread.  Thread#run kicks waiting thread with parameters.

  th = Thread.new(thread_config_params)
  ...
  th.run(params){|thread_local_params|
    ...
  }

We can combine with proc: parameter and this proposal.  If Thread.new() doesn't have block and proc: parameter, then making a waiting thread.

NOTE: Because we have already Thread#run, Thread#start is better than Thread#run?


= Note

I don't make any survey on other languages.  Please give us your comments.

=end



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