home_run is an implementation of ruby’s Date/DateTime classes in C,
with much better performance (20-200x) than the version in the
standard library, while being almost completely compatible.
== Performance increase (microbenchmarks)
The speedup you’ll get depends mostly on your version of ruby, but
also on your operating system, platform, and compiler. Here are
some comparative results for common methods:
| i386 | i386 | i386 | i386 | amd64 |
|Windows| Linux | Linux | Linux |OpenBSD|
| 1.8.6 | 1.8.7 | 1.9.1 | 1.9.2 | 1.9.2 |
Date.civil | 82x | 66x | 27x | 21x | 14x |
Date.parse | 56x | 56x | 33x | 30x | 25x |
Date.today | 17x | 6x | 2x | 2x | 2x |
Date.strptime | 43x | 62x | 63x | 37x | 23x |
DateTime.civil | 252x | 146x | 52x | 41x | 17x |
DateTime.parse | 52x | 54x | 32x | 27x | 20x |
DateTime.now | 78x | 35x | 11x | 8x | 4x |
DateTime.strptime | 63x | 71x | 58x | 35x | 23x |
Date#strftime | 156x | 104x | 110x | 70x | 62x |
Date#+ | 34x | 32x | 5x | 5x | 4x |
Date#<< | 177x | 220x | 86x | 72x | 40x |
Date#to_s | 15x | 6x | 5x | 4x | 2x |
DateTime#strftime | 146x | 107x | 114x | 71x | 60x |
DateTime#+ | 34x | 37x | 8x | 6x | 3x |
DateTime#<< | 88x | 106x | 40x | 33x | 16x |
DateTime#to_s | 144x | 47x | 54x | 29x | 24x |
== Real world difference
The standard library Date class is slow enough to be the
bottleneck in much (if not most) of code that uses it.
Here’s a real world benchmark showing the retrieval of
data from a database (using Sequel), first without home_run,
and then with home_run.
$ script/console production
Loading production environment (Rails 2.3.5)
0.270000 0.020000 0.290000 ( 0.460604)
2.510000 0.050000 2.560000 ( 2.967896)
$ home_run script/console production
Loading production environment (Rails 2.3.5)
0.100000 0.000000 0.100000 ( 0.114747)
0.860000 0.010000 0.870000 ( 0.939594)
Without changing any application code, there’s a 4x
increase when retrieving all employees, and a 3x
increase when retrieving all notifications. The
main reason for the performance difference between
these two models is that Employee has 5 date columns,
while Notification only has 3.
== Installing the gem
gem install home_run
The standard gem requires compiling from source, so you need a working
compiler toolchain. Since few Windows users have a working compiler
toolchain, a windows binary gem is available that works on both 1.8
== Installing into site_ruby
This is only necessary on ruby 1.8, as on ruby 1.9, gem directories
come before the standard library directories in the load path.
After installing the gem:
Installing into site_ruby means that ruby will always use home_run’s
Date/DateTime classes instead of the ones in the standard library.
If you ever want to uninstall from site_ruby:
== Running without installing into site_ruby
Just like installing into site_ruby, this should only be necessary
on ruby 1.8.
If you don’t want to install into site_ruby, you can use home_run’s
Date/DateTime classes for specific programs by running your script
home_run ruby …
home_run irb …
home_run unicorn …
home_run rake …
This manipulates the RUBYLIB and RUBYOPT environment variables so
that home_run’s Date/DateTime classes will be used.
You can also just require the library:
This should only be used as a last resort. Because rubygems requires
date, you can end up with situations where the Date instances created
before the require use the standard library version of Date, while the
Date instances created after the require use this library’s version.
However, in some cases (such as on Heroku), this is the only way to
easily use this library.
== Running the specs
You can run the rubyspec based specs after installing the gem, if
you have MSpec installed (gem install mspec):
If there are any failures, please report them as a bug.
== Running comparative benchmarks
You can run the benchmarks after installing the gem:
The benchmarks compare home_run’s Date/DateTime classes to the
standard library ones, showing you the amount of time an average
call to each method takes for both the standard library and
home_run, and the number of times home_run is faster or slower.
Output is in CSV, so an entry like this:
- The standard library’s Date._parse averaged 362,562 nanoseconds
- home_run’s Date._parse averaged 10,235 nanoseconds per call.
- Therefore, home_run’s Date._parse method is 35.42 times faster
The bench task tries to be fair by ensuring that it runs the
benchmark for at least two seconds for both the standard
library and home_run’s versions.
home_run aims to be compatible with the standard library, except
for differences mentioned below. So you can use it the same way
you use the standard library.
== Differences from standard library
- Written in C (mostly) instead of ruby. Stores information in a
C structure, and therefore has a range limitation. home_run
cannot handle dates after 5874773-08-15 or before -5877752-05-08
on 32-bit platforms (with larger limits for 64-bit platforms).
- The Date class does not store fractional days (e.g. hours, minutes),
or offsets. The DateTime class does handle fractional days and
- The DateTime class stores fractional days as the number of
nanoseconds since midnight, so it cannot deal with differences
less than a nanosecond.
- Neither Date nor DateTime uses rational. Places where the standard
library returns rationals, home_run returns integers or floats.
- Because rational is not used, it is not required. This can break
other libraries that use rational without directly requiring it.
- There is no support for modifying the date of calendar reform, the
sg arguments are ignored and the Gregorian calendar is always used.
This means that julian day 0 is -4173-11-24, instead of -4712-01-01.
- The undocumented Date#strftime format modifiers are not supported.
- The DateTime offset is checked for reasonableness. home_run
does not support offsets with an absolute difference of more than
14 hours from UTC.
- DateTime offsets are stored in minutes, so it will round offsets
with fractional minutes to the nearest minute.
- All public class and instance methods for both Date and DateTime
are implemented, except that the allocate class method is not
available and on 1.9, _dump and _load are used instead of
marshal_dump and marshal_load.
- Only the public API is compatible, the private methods in the
standard library are not implemented.
- The marshalling format differs from the one used by the standard
library. Note that the 1.8 and 1.9 standard library date
marshalling formats differ from each other.
- Date#step treats the step value as an integer, so it cannot handle
steps of fractional days. DateTime#step can handle fractional
day steps, though.
- When parsing the %Q modifier in _strptime, the hash returned
includes an Integer :seconds value and a Float :sec_fraction
value instead of a single rational :seconds value.
- The string returned by #inspect has a different format, since it
doesn’t use rational.
- The conversion of 2-digit years to 4-digit years in Date._parse
is set to true by default. On ruby 1.8, the standard library
has it set to false by default.
- You can use the Date::Format::STYLE hash to change how to parse
DD/DD/DD and DD.DD.DD date formats, allowing you to get ruby 1.9
behavior on 1.8 or vice-versa. This is probably the only new
feature in that isn’t in the standard library.
Any other differences will either be documented here or considered
bugs, so please report any other differences you find.
== Known incompatibilities
Some other libraries are known to be incompatible with this
extension due to the above differences:
- Date::Performance - Date#<=> assumes @ajd instance variable
(unnecessary anyway, as home_run is faster)
- ruby-ole - Depends on DateTime.allocate/#initialize
== Reporting issues/bugs
home_run uses GitHub Issues for tracking issues/bugs:
The source code is on GitHub:
To get a copy:
git clone git://github.com/jeremyevans/home_run.git
There are a few requirements:
- MSpec (not RSpec) for running the specs. The specs are based on
the rubyspec specs, which is why they use MSpec.
- RDoc 2.5.10+ if you want to build the documentation.
- Ragel 6.5+ if you want to modify the ragel parser.
To compile the library from a git checkout, after installing the
The default rake task runs the specs, so just run:
You need to compile the library and install MSpec before running the
To see the speedup that home_run gives you over the standard library:
To see how much less memory home_run uses compared to the standard
To see how much less garbage is created when instantiating objects
with home_run compared to the standard library:
If you want to run all three benchmarks at once:
== Platforms Supported
home_run has been tested on the following:
=== Operating Systems/Platforms
- Linux (x86_64, i386)
- Mac OS X 10.6 (x86_64, i386), 10.5 (i386)
- OpenBSD (amd64, i386)
- Solaris 10 (sparc)
- Windows XP (i386)
- Windows 7 (x64)
=== Compiler Versions
- gcc (3.3.5, 4.0.1, 4.2.1, 4.4.3, 4.5.0)
- Sun Studio Compiler (5.9)
=== Ruby Versions
- jruby cext branch (as of commit 1969c504229bfd6f2de1, 2010-08-23,
compiles and runs specs correctly, segfaults on benchmarks)
- rbx head (as of commit 0e265b92727cf3536053, 2010-08-16)
- ruby 1.8.6 (p0, p110, p398, p399)
- ruby 1.8.7 (p174, p248, p299, p302)
- ruby 1.9.1 (p243, p378, p429, p430)
- ruby 1.9.2 (p0)
- ruby head
If your platform, compiler version, or ruby version is not listed
above, please test and send me a report including:
- Your operating system and platform (e.g. i386, x86_64/amd64)
- Your compiler
- Your ruby version
- The output of home_run --spec
- The output of home_run --bench
Jeremy E. [email protected]