[ruby-core:86756] Re: [Ruby trunk Feature#14723] [WIP] sleepy GC

Could you give us more detail algorithm?

2018/04/29 12:57、[e-mail]のメール:

> Issue #14723 has been reported by normalperson (Eric Wong).
> 
> ----------------------------------------
> Feature #14723: [WIP] sleepy GC
> https://bugs.ruby-lang.org/issues/14723
> 
> * Author: normalperson (Eric Wong)
> * Status: Open
> * Priority: Normal
> * Assignee: 
> * Target version: 
> ----------------------------------------
> The idea is to use "idle time" when process is otherwise sleeping
> and using no CPU time to perform GC.  It makes sense because real
> world traffic sees idle time due to network latency and waiting
> for user input.
> 
> Right now, it's Linux-only.  Future patches will affect other sleeping
> functions:
> 
>  IO.select, Kernel#sleep, Thread#join, Process.waitpid, etc...
> 
> I don't know if this patch can be implemented for win32, right
> now it's just dummy functions and that will be somebody elses
> job.  But all pthreads platforms should eventually benefit.
> 
> 
> Before this patch, the entropy-dependent script below takes 95MB
> consistently on my system.  Now, depending on the amount of
> entropy on my system, it takes anywhere from 43MB to 75MB.
> 
> I'm using /dev/urandom to simulate real-world network latency
> variations.  There is no improvement when using /dev/zero
> because the process is never idle.
> 
>  require 'net/http'
>  require 'digest/md5'
>  Thread.abort_on_exception = true
>  s = TCPServer.new('127.0.0.1', 0)
>  len = 1024 * 1024 * 1024
>  th = Thread.new do
>    c = s.accept
>    c.readpartial(16384)
>    c.write("HTTP/1.0 200 OK\r\nContent-Length: #{len}\r\n\r\n")
>    IO.copy_stream('/dev/urandom', c, len)
>    c.close
>  end
> 
>  addr = s.addr
>  Net::HTTP.start(addr[3], addr[1]) do |http|
>    http.request_get('/') do |res|
>      dig = Digest::MD5.new
>      res.read_body { |buf|
>        dig.update(buf)
>      }
>      puts dig.hexdigest
>    end
>  end
> 
> The above script is also dependent on net/protocol using
> read_nonblock.  Ordinary IO objects will need IO#nonblock=true
> to see benefits (because they never hit rb_wait_for_single_fd)
> 
> * gc.c (rb_gc_inprogress): new function
>  (rb_gc_step): ditto
> * internal.h: declare prototypes for new gc.c functions
> * thread_pthread.c (gvl_contended_p): new function
> * thread_win32.c (gvl_contended_p): ditto (dummy)
> * thread.c (rb_wait_for_single_fd w/ ppoll):
>  use new functions to perform GC while GVL is uncontended
>  and GC is lazy sweeping or incremental marking
>  [ruby-core:86265]
> ```
> 
> 2 part patch broken out
> https://80x24.org/spew/[e-mail]/raw
> https://80x24.org/spew/[e-mail]/raw
> 
> Also on my "sleepy-gc" git branch @ git://80x24.org/ruby.git
> 
> 
> ---Files--------------------------------
> sleepy-gc-wip-v1.diff (5.37 KB)
> 
> 
> -- 
> https://bugs.ruby-lang.org/
> 
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