From: chopraanmol1@...
Date: 2018-08-21T04:46:04+00:00
Subject: [ruby-core:88585] [Ruby trunk Feature#15010] Reduce allocation for	rest parameters

Issue #15010 has been updated by chopraanmol1 (Anmol Chopra).


normalperson (Eric Wong) wrote:
>  
>  New functions prototypes should go into internal.h, though.
>  ruby/intern.h ended up being part of the public API and external
>  libraries depend on it :<
>  
>  There's no reason for arg_rest_dup to be a macro instead of a
>  static inline function.  Static inlines are preferred because
>  they make life easier for the compiler and debugger.
>  

Updated.



mame (Yusuke Endoh) wrote:
>
> First, the prefix `_m` is often used for an entry function of Ruby-level method that is passed to `rb_define_method`.  Though it is just an internal function, it would be better to avoid the prefix.  How about `rb_ary_remove_first`?
> 

For now, I'm renaming the method to rb_ary_behead (suggested by nobu)




----------------------------------------
Feature #15010: Reduce allocation for rest parameters
https://bugs.ruby-lang.org/issues/15010#change-73642

* Author: chopraanmol1 (Anmol Chopra)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
Currently multiple arrays are allocated while making a call to method with rest parameter.

E.g.
~~~
def rest_method(*args) #-> This will create 2 arrays
end

def post_method(*args,last) #-> This will create 3 arrays
end
~~~

Applying following set of changes will reduce creation of array to 1

https://github.com/ruby/ruby/pull/1935

Benchmark Result:

trunk
~~~
                                  user     system      total        real
benchmark_method              0.340000   0.000000   0.340000 (  0.337035)
rest_method                   0.964000   0.000000   0.964000 (  0.964660)
lead_method                   0.976000   0.000000   0.976000 (  0.976011)
post_method                   2.424000   0.000000   2.424000 (  2.421732)
lead_post_method              1.800000   0.000000   1.800000 (  1.799500)
rest_with_named_parameter     2.040000   0.000000   2.040000 (  2.040323)
lead_proc underflow_args      1.224000   0.000000   1.224000 (  1.225237)
opt_post_proc overflow_args   1.056000   0.000000   1.056000 (  1.057402)
~~~

modified
~~~
                                  user     system      total        real
benchmark_method              0.336000   0.000000   0.336000 (  0.336911)
rest_method                   0.708000   0.000000   0.708000 (  0.706142)
lead_method                   0.720000   0.000000   0.720000 (  0.717971)
post_method                   1.896000   0.000000   1.896000 (  1.894426)
lead_post_method              1.560000   0.000000   1.560000 (  1.560495)
rest_with_named_parameter     1.464000   0.000000   1.464000 (  1.467313)
lead_proc underflow_args      0.864000   0.000000   0.864000 (  0.863980)
opt_post_proc overflow_args   0.772000   0.000000   0.772000 (  0.770364)
~~~

---Files--------------------------------
bench_method_arg.rb (1.32 KB)
0001-Reduce-allocation-for-rest-parameters.patch (7.71 KB)


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