Ruby Interpreters By Katlyn Parvin 01001000 01100101 01101100 01101100 01101 

MRI Matz’s Ruby Interpreter JRuby In particular... & 

But before we get to tonight’s main event... 

Interpreters Let’s learn a little about them! ● Why do we need an interpreter? ● How do they work? ? 

Interpreter A computer program that interprets and translates source code into a format that the computer can understand. 

To start at the beginning... we will have to travel back in time to the early 1940s ● Before the first interpreter in 1958 programs were written in assembly ● Assembly languages required a lot of knowledge about the hardware and were very error-prone ● Programs needed to be written in a way that the processor could understand 

Ex. MIPS Assembly Language Load the data at location 32($s3) in memory to the local register $t0 Perform the addition of $t0 and $s2 and store the result in register $t0 Store the value of register $t0 to location 48($s3) in memory Ruby Program my_array[12] = 10 + my_array[8] Equivalent MIPS Program 

High-level Languages Strongly abstracted from the implementation details of the computer C Java C++ Ruby 

● Scans the entire program and translates it as a whole ● Fast execution time ● Compile once -> run many times Compiler ● Translates the program one statement at a time ● Slower execution time ● Faster analysis of the program ● Translates the source code every time it is run Interpreter Converting from high-level language or 

Cool but, how do interpreters work? 

Let’s see how things work inside of MRI 

Example Code # Ruby Example x = 10 y = 5 puts x + y 

Step 1 Tokenize Breakdown the ruby code into structured data # Ruby Example x = 10 y = 5 puts x + y 

Step 2 Lexical Analysis Tagging each token as an identifier, operator or integer # Ruby Example x = 10 y = 5 puts x + y 

Step 3 Build a Abstract Syntax Tree Representation of your program in memory # Ruby Example x = 10 y = 5 puts x + y 

Step 4 Compile to Bytecode Run in YARV the ruby VM (Ruby 1.9+) # Ruby Example x = 10 y = 5 puts x + y 

If you want to learn more about interpreters... I would highly recommend this talk by Ryan Davis From the 2013 Golden Gate Ruby Conf https://youtu.be/RPxvx9OkNic 

But back to MRI and JRuby... 

MRI Matz’s Ruby Interpreter - Written in C by the core Ruby team - Sets the standard for the Ruby Language - Well maintained with more paid core team members than any other Ruby Implementation - Consistent release cycle - Most likely what you are using to interpret Ruby 

JRuby - Written in primarily java - Implemented on top of the JVM - Which means you can run Ruby code anywhere Java can run. - Ruby 2.3 Compatible - Actively being maintained - Supports true parallel multi-threading - Not all gems work with JRuby 

Cool things about JRuby ● Use Java libraries ○ Great for companies that maintain Java codebases ○ Utilize 3rd party Java Libraries ■ Ex. Android development (ruboto) ● Use ruby in your Java files ○ Ex. utilize a ruby codebase within an existing Java app ● Allows for a lot more performance optimizations options ○ Tuning the JIT compiler ○ Threading 

True Multi-Threading ● Ruby 1.8.7 the GIL (Global Interpreter Lock) prevent more than 1 thread of Ruby code to run at any time. ● Ruby 1.9+ can use multiple OS threads for I/O bound operations, but we cannot have parallel ruby processes ● JRuby can use true OS threads allowing us to utilize multiple CPUs http://www.restlessprogrammer.com/2013/02/multi-threading-in-jruby.html 

Other interpreters to keep an eye on... Designed by Matz to be an embeddable implementation of Ruby Ruby interpreter written in RPython Implementation of Ruby that implements a generic runtime for dynamic languages on top of a Low Level Virtual Machine (LLVM) mRuby Topaz Rubinius Many more... 

MRI Matz’s Ruby Interpreter JRuby In conclusion... & 

Thank you! Katlyn Parvin Director of Engineering @ Mavenlink We are hiring! www.mavenlink.com/careers @KatlynParvin [email protected]