I'm neutral (at least no against it). __send__ in general has other usages than to reroute method visibilities. Optimising it could benefit good wills.

I found that rspec-core redefines __send__.

https://.com/rspec/rspec-mocks/blob/461d7f6f7f688f69154e410dcd9c7690120e7dbf/lib/rspec/mocks/verifying_double.rb#L45-L53

It seems this s memory?

`nproc --all`.to_i.times.map do |i|
  Ractor.new :"#{i}_0" do |sym|
    while true do
      __send__(sym = sym.succ) rescue nil 
    end
  end
end

while true do
  sleep 1
  GC.start
  p GC.stat(:heap_live_slots)
end

I see very different output comparing the proposed implementation versus master.

Yeah I don't think a warning is good enough to prevent people overriding it.
It should be an exception if the goal is to prevent overriding it.

I think we should not compromise semantics for optimizations, that usually leads to more complicated semantics that alternative Ruby implementations have to replicate (which is nonsense if those implementations would check it correctly if redefined).
As an example, the optimization for Hash#each_pair led to very confusing semantics where lambdas/Method#to_proc appear to unsplat/destructure arguments (they do not, it's just a side effect of the incorrect optimization).

shyouhei (Shyouhei Urabe) wrote in #note-4:

It seems this s memory?

`nproc --all`.to_i.times.map do |i|
  Ractor.new :"#{i}_0" do |sym|
    while true do
      __send__(sym = sym.succ) rescue nil 
    end
  end
end

while true do
  sleep 1
  GC.start
  p GC.stat(:heap_live_slots)
end

I see very different output comparing the proposed implementation versus master.

I used SYM2ID in compile_call function and sendsym and opt_sendsym_without_block instructions. This SYM2ID makes dynamic symbols permanent, so many symbols remained in the heap. This is the reason for the observed phenomenon.

I added a commit to fix this bug.

The new benchmark result is below:

# Iteration per second (i/s)

|                     |compare-ruby|built-ruby|
|:--------------------|-----------:|---------:|
|vm_send_sym          |     18.265M|  113.593M|
|                     |           -|     6.22x|
|vm_send_var          |     17.750M|   31.974M|
|                     |           -|     1.80x|
|vm_send_var_alt      |      3.955M|    7.499M|
|                     |           -|     1.90x|
|vm_send_sym_missing  |      7.135M|    8.982M|
|                     |           -|     1.26x|
|vm_send_var_missing  |      7.271M|    7.454M|
|                     |           -|     1.03x|

mrkn (Kenta Murata) wrote in #note-3:

I found that rspec-core redefines __send__.

https://.com/rspec/rspec-mocks/blob/461d7f6f7f688f69154e410dcd9c7690120e7dbf/lib/rspec/mocks/verifying_double.rb#L45-L53

This redefinition is used to distinguish the form of the method call in a mock object.
rspec-mocks recognizes that the form of recv.__send__(:meth) is used when __send__ is called before method_missing is called, or the form of recv.meth is used when otherwise.

The feature to distinguish method calling form is necessary to keep the compatibility if we employ this optimization of __send__ call.