Enabling ttyO1 on BeagleBone | Tenderlove Making
I’m really just making this post because I will eventually forget how to do this, and maybe it will come in handy to others as well. Hardware I’ve got an MSP430 reading temperature and humidity information from an RHT03 sensor. It sends the data over a serial port, and I’d like to read that data on my BeagleBone. I have P1.1 and P1.2 on the launchpad connected to pin 24 and 26 on the BeagleBone. P
Inline caching in MRI | Tenderlove Making
Inline Caching Every time you call a method, Ruby must look up the method you want to call before actually calling that method. Trying to figure out what method needs to be called can be a costly operation. So one thing that virtual machine authors try to do is to speed up that process by caching the method lookup. MRI (and most other Ruby virtual machines) store this cache “inline”. Most of us kn
Tenderlove Making - Speeding up Ruby with Shared Strings
It’s not often I am able to write a patch that not only reduces memory usage, but increases speed as well. Usually I find myself trading memory for speed, so it’s a real treat when I can improve both in one patch. Today I want to talk about the patch I submitted to Ruby in this ticket. It decreases “after boot” memory usage of a Rails application by 4% and speeds up require by about 35%. When I wa
Object ID in MRI | Tenderlove Making
Objects in Ruby are 40 bytes. Objects are allocated in to pages (or arenas) that are 2^14 (2 to the 14th power) bytes. Pages are allocated with an aligned malloc where the divisor is the size of a page. The first object is allocated at the first address inside the page that is divisible by 40 (or page_start + (40 - page_start % 40) % 40). This means all Ruby object addresses are divisible by 40, a
Tenderlove Making | tenderlovemaking.com
Lately I’ve been messing around with writing a GraphQL parser called TinyGQL. I wanted to see how fast I could make a GraphQL parser without writing any C extensions. I think I did pretty well, but I’ve learned some tricks for speeding up parsers and I want to share them. Today we’re going to specifically look at the lexing part of parsing. Lexing is just breaking down an input string in to a seri
Reducing Memory Usage in Ruby | Tenderlove Making
I’ve been working on building a compacting garbage collector in Ruby for a while now, and one of the biggest hurdles for implementing a compacting GC is updating references. For example, if Object A points to Object B, but the compacting GC moves Object B, how do we make sure that Object A points to the new location? Solving this problem has been fairly straight forward for most objects. Ruby’s ga
Reducing Memory Usage in Ruby | Tenderlove Making
I’ve been working on building a compacting garbage collector in Ruby for a while now, and one of the biggest hurdles for implementing a compacting GC is updating references. For example, if Object A points to Object B, but the compacting GC moves Object B, how do we make sure that Object A points to the new location? Solving this problem has been fairly straight forward for most objects. Ruby’s ga
Tenderlove Making - Visualizing Your Ruby Heap
In a previous post, I wrote a bit about how Ruby objects are laid out in memory. Today we’ll use that information to write a program that will allow us to take a Ruby heap dump and visualize the layout and fragmentation of that heap. Ruby Object Layout Recap Just as a recap, Ruby objects are fixed width. That is, every Ruby object is the same size: 40 bytes. Objects are not really allocated with m
Removing config.threadsafe! | Tenderlove Making
TL;DR: config.threadsafe! can be removed, but for Rails 4.0 we should just enable it by default. A while back a ticket was filed on the Rails tracker to turn on config.threadsafe! mode by default in production. Unfortunately, this change was met with some resistance. Rather than make resistance to change a negative thing, I would like to make it a positive thing by talking about exactly what confi
Tenderlove Making - Object ID in MRI
Objects in Ruby are 40 bytes. Objects are allocated in to pages (or arenas) that are 2^14 (2 to the 14th power) bytes. Pages are allocated with an aligned malloc where the divisor is the size of a page. The first object is allocated at the first address inside the page that is divisible by 40 (or page_start + (40 - page_start % 40) % 40). This means all Ruby object addresses are divisible by 40, a
Tenderlove Making - Evented GPIO on Raspberry PI with Ruby
I need to know when my cats are pooping so over the weekend I hooked up a motion sensor to my Raspberry PI. This is the code I used to get an interrupt when the motion sensor turns on or off: require 'epoll' def watch pin, on: # Export the pin we want to watch File.binwrite "/sys/class/gpio/export", pin.to_s # It takes time for the pin support files to appear, so retry a few times retries = 0 begi
Profiling Rails startup with DTrace | Tenderlove Making
TL;DR: I’m adding DTrace probes to Ruby, and I used those to make a 6% performance improvement to rake environment. Lately I've been working on adding DTrace probes to Ruby 2.0. I am interested in using them to profile and improve rails startup time. Today I want to look at building a profiler with DTrace, finding slow method calls, and making some incremental improvements. The examples I'm going
Tenderlove Making - Connection Management in ActiveRecord
File.open('somefile.txt', 'wb') do |fh| # Open the file fh.write "hello world" # Do some work with the file end # Close file when block returns ActiveRecord::Base.establish_connection( :adapter => "sqlite", :database => "path/to/dbfile") connection_handle = ActiveRecord::Base.connection def retrieve_connection_pool(klass) pool = @connection_pools[klass.name] return pool if pool return nil if Activ
Tenderlove Making - I am a puts debuggerer
Update (2023-06-28): Added “I required a file, but I want to know what files were actually loaded” I love puts debugging I am a puts debuggerer. I don’t say this to disparage people that use a Real Debugger. I think Real Debuggers are great, I’ve just never taken the time to learn one well. Every time I try to lean one, I end up not using it for a while and have to re-learn how to use it. Anyway,
Tenderlove Making - Inline caching in MRI
Inline Caching Every time you call a method, Ruby must look up the method you want to call before actually calling that method. Trying to figure out what method needs to be called can be a costly operation. So one thing that virtual machine authors try to do is to speed up that process by caching the method lookup. MRI (and most other Ruby virtual machines) store this cache “inline”. Most of us kn
Tenderlove Making - Rack API is awkward
TL;DR: Rack API is poor when you consider streaming response bodies. class FooApplication class ErbPage def to_a head = "the head tag" sleep(2) body = "the body tag" sleep(2) [head, body] end end def call(env) [200, {}, ErbPage.new.to_a] end end class FakeRack def serve(application) status, headers, body = application.call({}) p :status => status p :headers => headers body.each do |string| p strin
String Encoding in Ruby 1.9 C extensions | Tenderlove Making
One of the challenges of developing nokogiri has been dealing with String encodings in C. I would like to present one of the problems encountered, along with a solution. I will be using RubyInline in the examples below, but the C code presented should be easy to port to your own C extensions. Examining the Encoding If you’ve developed a C extension before, you’re probably familiar with rb_str_new2
johnson – Tender Lovemaking
The other day at LA RubyConf during the Johnson presentation, I showed a few slides which I don’t think were given the time that they deserve. Not that we didn’t have enough time, I just don’t think I made as big a deal about them as I should have. Those particular slides demonstrated HTML Document Object manipulation executed in JavaScript outside any web browser. Those particular slides, and tha
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Tenderlove Making - Visualizing Your Ruby Heap
http://tenderlovemaking.com/entries/eckbert-master/