Speeding Ducks Avi Bryant Meta Heckling welcomed. Ruby is slow - PowerPoint PPT Presentation

Speeding Ducks Avi Bryant

Meta Heckling welcomed.

Ruby is slow “So what?” “Of course!”

So what? “The Ruby language may be slow, but my app runs plenty fast” True.

Ruby ary.pop C VALUE rb_ary_pop(ary) VALUE ary; { rb_ary_modify_check(ary); if (RARRAY(ary)->len == 0) return Qnil; if (!FL_TEST(ary, ELTS_SHARED) && � RARRAY(ary)->len * 2 < RARRAY(ary)->aux.capa && � RARRAY(ary)->aux.capa > ARY_DEFAULT_SIZE) { � RARRAY(ary)->aux.capa = RARRAY(ary)->len * 2; � REALLOC_N(RARRAY(ary)->ptr, VALUE, RARRAY(ary)->aux.capa); } return RARRAY(ary)->ptr[--RARRAY(ary)->len]; }

ary.pop Java /** rb_ary_pop * */ public IRubyObject pop() { modify(); if (getLength() == 0) { return getRuntime().getNil(); } return (IRubyObject) list.remove(getLength() - 1); }

ary.pop Smalltalk

Ruby �� def pop () ���� return nil if empty? � ���� @total -= 1 ���� index = @start + @total � ���� elem = @tuple . at(index) ���� @tuple . put(index, nil ) � ���� reallocate_shrink() � ���� elem �� end C | Java | Smalltalk | ...

VALUE rb_ary_pop(ary) VALUE ary; { rb_ary_modify_check(ary); if (RARRAY(ary)->len == 0) return Qnil; if (!FL_TEST(ary, ELTS_SHARED) && � RARRAY(ary)->len * 2 < RARRAY(ary)->aux.capa && � RARRAY(ary)->aux.capa > ARY_DEFAULT_SIZE) { � RARRAY(ary)->aux.capa = RARRAY(ary)->len * 2; � REALLOC_N(RARRAY(ary)->ptr, VALUE, RARRAY(ary)->aux.capa); } return RARRAY(ary)->ptr[--RARRAY(ary)->len]; } vs �� def pop () ���� return nil if empty? � ���� @total -= 1 ���� index = @start + @total � ���� elem = @tuple . at(index) ���� @tuple . put(index, nil ) � ���� reallocate_shrink() � ���� elem �� end

Of course! “Ruby is inherently slow because it is so dynamic.” False.

Smalltalk-80

Efficient Implentation of the Smalltalk-80 System L. Peter Deutsch Alan M. Schiffman 1984

Deutsch, 1984 - Native Code cache �� def foo (duck) mov ... ���� duck.waddle cmp ... �� end

Deutsch, 1984 - Native Code invalid �� def foo (duck) mov ... ���� duck.quack! cmp ... �� end

Deutsch, 1984 - Inline Caching 0xDECAF address = lookup(duck, :quack!) �� def foo (duck) push duck ���� duck.quack! jump(address) �� end 0xBEEF �� def quack! ... ���� puts “quack” �� end

Deutsch, 1984 - Inline Caching 0xDECAF �� def foo (duck) push duck ���� duck.quack! jump(0xBEEF) �� end 0xBEEF �� def quack! ... ���� puts “quack” �� end

Deutsch, 1984 - Inline Caching 0xDECAF �� def foo (duck) push duck ���� duck.quack! jump(0xBEEF) �� end 0xBEEF unless self.class == Duck �� def quack! jump(lookup(self.class, :quack!) ���� puts “quack” end �� end ...

Deutsch, 1984 - Inline Caching 0xDECAF �� def foo (duck) push duck ���� duck.quack! jump(0xBEEF) �� end 0xBEEF unless self.class == Duck �� def quack! jump(lookup(self.class, :quack!) � play “q.wav” end �� end ...

Deutsch, 1984 - Inline Caching 0xDECAF address = �� def foo (duck) push duck duck.vtable[3] ���� duck.quack! jump(0xBEEF) jump address �� end 0xBEEF unless self.class == Duck �� def quack! jump(lookup(self.class, :quack!) ���� puts “quack” end �� end ...

SOAR: Smalltalk without Bytecodes David Ungar Dain Samples Paul Hilfinger 1986

Self

Customization: Optimizing Compiler Technology for Self David Ungar Craig Chambers 1989

Optimizing Dynamically-Dispatched Calls with Run-Time Type Feedback David Ungar Urs Hölzle 1994

Self - Polymorphic Inline Caches Duck: 42 �� def foo (duck) Goose: 7 ���� duck.waddle Doctor: 1 �� end

Self - Type feedback inlining �� def foo (duck) if duck.class == Duck ���� duck.quack! puts “quack” �� end else ... end �� def quack! puts “quack” �� end

Self - Type feedback inlining �� def foo (range) ���� range.collect{|x| x * 2} �� end �� def foo (range) result = [] ���� range.each do |x| result.push(x * 2) end result �� end

Self - Type feedback inlining �� def foo (range) ���� range.collect{|x| x * 2} �� end �� def foo (range) result = [] i = range.first while(i <= range.last) result.push(i * 2) i += 1 end result �� end

Self - Type feedback inlining �� def foo (range) ���� range.collect{|x| x * 2} �� end �� def foo (range) result = [] i = range.first while(i <= range.last) result.push(i << 1) i = i + 1 end result �� end

Strongtalk Ungar, Hölzle, Lars Bak, et al

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