MRI: Difference between revisions

From Rosetta Code
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(Describe Global VM Lock, core library, YARV and such.)
(Describe advantages and disadvantages.)
 
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{{implementation|Ruby}}
{{implementation|Ruby}}
{{infobox begin}}<lang ruby>if RUBY_VERSION >= "1.9"
{{infobox begin}}<lang ruby>RUBY_ENGINE == "ruby"</lang>{{infobox end}}
p RUBY_ENGINE
# => "ruby"
end</lang>{{infobox end}}


''Matz's Ruby Implementation'' or ''MRI'' refers to the original [[Ruby]] interpreter by Yukihiro Matsumoto, the inventor of Ruby. Matz and contributors wrote the interpreter in [[implemented in language::C|C language]]; MRI is also known as ''C Ruby'' or ''CRuby'', by analogy with [[CPython]].
''Matz's Ruby Implementation'' or ''MRI'' refers to the original [[Ruby]] interpreter by Yukihiro Matsumoto, the inventor of Ruby. Matz and contributors wrote the interpreter in [[implemented in language::C|C language]]; MRI is also known as ''C Ruby'' or ''CRuby'', by analogy with [[CPython]].


The term "MRI" excludes other Ruby engines (such as [[JRuby]] or [[Rubinius]]). For example, one can say that Ruby has Array#sort method, and MRI uses [[Sorting algorithms/Quicksort|quicksort]]; other Ruby engines might use different sorting algorithm.
⚫
Other implementations of Ruby follow MRI. When an example on Rosetta Code works with Ruby 1.8.7, this can be MRI 1.8.7, or anything else that implements the same language.


⚫
When code works with Ruby 1.8.7, this can be MRI 1.8.7, or anything else that implements the same language.
* Ruby 1.8.7 adds Array#permutation method. This means that MRI 1.8.7 has Array#permutation, and other implementations of Ruby 1.9.2 must also have Array#permutation.
* MRI implements Array#sort with [[Sorting algorithms/Quicksort|quicksort]]. Other implementations of Ruby might use different sorting algorithm.


== Advantages ==
⚫
MRI has the ''Global VM Lock'', alias ''Giant VM Lock'' or ''GVL''. Each thread that runs Ruby code must hold this exclusive lock; therefore, multiple threads can use only CPU. (Contrast [[JRuby]], where multiple threads might use multiple CPUs.)
* MRI is the [[reference implementation]], and the first implementation of every new Ruby version.
* MRI can fork, though only for [[Unix]] clones (not for [[Windows]]).
* MRI can save and restore [[:Category:continuation|continuations]], though the implementation is slow because it copies the call stack.

== Disadvantages ==
⚫
* MRI has the ''Global VM Lock'', alias ''Giant VM Lock'' or ''GVL''. A thread, to run Ruby code, must hold this exclusive lock. Only one thread can hold the GVL; therefore, multiple threads can use only one CPU. (Contrast [[JRuby]], where multiple threads can use multiple CPUs.)
* MRI 1.8 is slow. Programs for Ruby 1.8 often run faster in [[JRuby]] or [[Rubinius]].


== Features ==
== Features ==
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# the core and standard libraries.
# the core and standard libraries.


The entire core library is in C. The standard library is a mix of Ruby code and C extensions.
Most of the core library is in C. The standard library is a mix of Ruby code and C extensions.


MRI 1.8 has a somewhat slow interpreter. MRI 1.9 has a new interpreter called Yet Another Ruby VM (YARV); it translates Ruby source code to an internal [[bytecode]], then interprets the bytecode. Ruby code can run a few times faster in MRI 1.9 than in MRI 1.8. Ruby code remains slower than C code. For example, MRI 1.9.3 changes its 'date' package from Ruby code to a C extension; this gives better performance.
MRI 1.8 has a somewhat slow interpreter. MRI 1.9 has a new interpreter called Yet Another Ruby VM (YARV); it translates Ruby source code to an internal [[bytecode]], then interprets the bytecode. Ruby code can run a few times faster in MRI 1.9 than in MRI 1.8. Ruby code remains slower than C code. For example, MRI 1.9.3 changes its 'date' package from Ruby code to a C extension; this gives better performance.

Latest revision as of 03:09, 21 February 2012

MRI is an implementation of Ruby. Other implementations of Ruby.
<lang ruby>RUBY_ENGINE == "ruby"</lang>

Matz's Ruby Implementation or MRI refers to the original Ruby interpreter by Yukihiro Matsumoto, the inventor of Ruby. Matz and contributors wrote the interpreter in C language; MRI is also known as C Ruby or CRuby, by analogy with CPython.

The term "MRI" excludes other Ruby engines (such as JRuby or Rubinius). For example, one can say that Ruby has Array#sort method, and MRI uses quicksort; other Ruby engines might use different sorting algorithm.

When code works with Ruby 1.8.7, this can be MRI 1.8.7, or anything else that implements the same language.

Advantages

  • MRI is the reference implementation, and the first implementation of every new Ruby version.
  • MRI can fork, though only for Unix clones (not for Windows).
  • MRI can save and restore continuations, though the implementation is slow because it copies the call stack.

Disadvantages

  • MRI has the Global VM Lock, alias Giant VM Lock or GVL. A thread, to run Ruby code, must hold this exclusive lock. Only one thread can hold the GVL; therefore, multiple threads can use only one CPU. (Contrast JRuby, where multiple threads can use multiple CPUs.)
  • MRI 1.8 is slow. Programs for Ruby 1.8 often run faster in JRuby or Rubinius.

Features

MRI has

  1. an interpreter,
  2. a mark-and-sweep garbage collector, and
  3. the core and standard libraries.

Most of the core library is in C. The standard library is a mix of Ruby code and C extensions.

MRI 1.8 has a somewhat slow interpreter. MRI 1.9 has a new interpreter called Yet Another Ruby VM (YARV); it translates Ruby source code to an internal bytecode, then interprets the bytecode. Ruby code can run a few times faster in MRI 1.9 than in MRI 1.8. Ruby code remains slower than C code. For example, MRI 1.9.3 changes its 'date' package from Ruby code to a C extension; this gives better performance.

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