Activerecord-jdbc-adapter 0.8.1 Released

Posted by Nick Sieger Wed, 04 Jun 2008 21:57:00 GMT

The long-delayed and much-awaited 0.8.1 release is here. It fixes quite a few reported bugs (but not quite all). See the full changelog below for details.

Please help me make more frequent releases of ar-jdbc by submitting patches against the trunk of activerecord-jdbc. Test cases appreciated also.

File bugs in JRuby’s JIRA. Use the “ActiveRecord-JDBC” component when filing them.

You can check out the source here:

svn co
git clone git://

Recently I started keeping a mirror of activerecord-jdbc-adapter on Github. Feel free to watch or fork and send me patches via git format-patch as well.

One of the cool new things in this release is a JDBC version of sqlite3 using the Zentus Sqlite JDBC driver. The crazy thing is how the driver is created. The original sqlite3 codebase is cross-compiled to MIPS and the resulting output coverted to Java bytecode using NestedVM! The adapter is still in its early stages, but basic stuff seems to be working. Try it out using jruby -S gem install activerecord-jdbcsqlite3-adapter.

Let me know how the release works for you!

Changes in 0.8.1

  • Now sporting a JDBC sqlite3 adapter! Thanks Joseph Athman.
  • Added support for InterSystems Cache database (Ryan Bell)
  • Fix for JRUBY-2256
  • JRUBY-1638, JRUBY-2404, JRUBY-2463: schema.table handling and Oracle NUMBER fixes (Darcy Schultz & Jesse Hu)
  • Add structure dump and other DDL-ish for DB2 (courtesy abedra and stuarthalloway)
  • Fix missing quotetablename function under Rails 1.2.6 and earlier
  • Small tweaks to jdbc.rake to select proper config
  • JRUBY-2011: Fix MSSQL string un-quoting issue (Silvio Fonseca)
  • JRUBY-1977, 17427: Fix information_schema select issue with MSSQL (Matt Burke)
  • 20479: Improve gettablename for MSSQL (Aslak Hellesøy)
  • 20243: numerics improvements for MSSQL (Aslak Hellesøy)
  • 20172: don’t quote table names for MSSQL (Thor Marius Henrichsen)
  • 19729: check for primary key existence in postgres during insert (Martin Luder)
  • JRUBY-2297, 18846: retrying failing SQL statements is harmful when not autocommitting (Craig McMillan)
  • 10021: very preliminary sybase support. (Mark Atkinson) Not usable until collision w/ sqlserver driver is resolved.
  • JRUBY-2312, JRUBY-2319, JRUBY-2322: Oracle timestamping issues (Jesse Hu & Michael König)
  • JRUBY-2422: Fix MySQL referential integrity and rollback issues
  • JRUBY-2382: mysql string quoting fails with ArrayIndexOutofBoundsException

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Introducing JRuby-Rack

Posted by Nick Sieger Thu, 08 May 2008 17:31:00 GMT

Continuing in the spirit of Conference-Driven Development, I’m happy to announce the first public release of JRuby-Rack! You can use it to run Rails, Merb, or any Rack-compatible application inside a Java application server.

Also released today is Warbler 0.9.9, which has been updated to bundle JRuby-Rack.

In addition to providing as seamless a connection as possible between the servlet environment and Rack, JRuby-Rack (along with Warbler) is also bridging the gap between Ruby and Java web development. Some of the things it does are:

  • Makes the Java servlet context and servlet request available to Ruby through special variables in the Rack environment
  • Servlet request attributes from Java are passed through and available in the Rack environment. Request attributes can override Rack variables such as PATH_INFO, QUERY_STRING etc.
  • Configures Rails deployment options such as page caching directories and session handling automatically and optimally for the servlet environment.

I’ve also included the beginnings of some extensions that should help integrate Rails with existing Java web frameworks, servlets, JSPs, and other code. For example, you can invoke a Rails request from within a JSP with a tag:

<jruby-rack:rails path="/projects/activity" params="layout=none"/>

You can set servlet and session attributes and forward to other servlets and JSPs from your Rails controllers:

class DemoController < ApplicationController
  def index
    servlet_request["hello"] = "world!"
    session["rails"] = "Visible to java!"
    forward_to "/attributes.jsp"

and read them from within the servlet or JSP:

  <dt><tt>servlet_request["hello"] | request.getAttribute("hello")</tt></dt>
  <dd><%= request.getAttribute("hello") %></dd>
  <dt><tt>session["rails"] | session.getAttribute("rails")</tt></dt>
  <dd><%= session.getAttribute("rails") %></dd>

This is just the beginning of this kind of integration, and I’m interested where people take it. I think this provides a nifty way to start integrating Rails bits into existing applications or reuse existing Java web application code.

I’ve tagged the release with an 0.9 version number. I believe the bits are ready for serious use, but could use some help pounding out a few more bugs before calling it 1.0. So jruby -S gem install warbler today, try it out, and bring plenty of feedback to the JRuby user list!

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Next performance fix: Builder::XChar

Posted by Nick Sieger Thu, 17 Jan 2008 23:48:00 GMT

Next up in our performance series: Builder::XChar. (Another fine Sam Ruby production!) While this piece of code in the Builder library strikes me as perfectly fine, it also tends to slow down quite a bit with larger documents or chunks of text.

Our path to the bottleneck is as follows: ActiveRecord::Base#to_xml => Builder::XMLMarkup#text! => String#to_xs => Fixnum#xchr. Consider:

require 'rubygems'
gem 'activesupport'
require 'active_support'
require 'benchmark'

module Benchmark
  class << self
    def report(&block)
      n = 10
      times = (1..10).map do
        bm = measure(&block)
        puts bm
      sum = times.inject(0) {|s,t| s + t.real}
      mean = sum / n
      sumsq = times.inject(0) {|s,t| s + t.real * t.real}
      sd = Math.sqrt((sumsq - (sum * sum / n)) / (n - 1))
      puts("Mean: %0.6f SDev: %0.6f" % [mean, sd])

page ="page.xml") {|f| } do
  20.times { page.to_xs }

On Ruby and JRuby, this produces:

$ ruby to_xs.rb 
 21.430000   0.400000  21.830000 ( 22.022769)
 21.530000   0.360000  21.890000 ( 22.005737)
 21.540000   0.370000  21.910000 ( 22.065165)
 21.530000   0.370000  21.900000 ( 22.028591)
 21.500000   0.350000  21.850000 ( 21.990395)
 21.550000   0.370000  21.920000 ( 22.033164)
 21.520000   0.360000  21.880000 ( 21.984129)
 21.550000   0.370000  21.920000 ( 22.116802)
 21.550000   0.370000  21.920000 ( 22.051421)
 21.520000   0.380000  21.900000 ( 22.084736)
Mean: 22.038291 SDev: 0.041985

$ jruby -J-server to_xs.rb
 79.112000   0.000000  79.112000 ( 79.112000)
 81.480000   0.000000  81.480000 ( 81.481000)
 84.745000   0.000000  84.745000 ( 84.745000)
 84.384000   0.000000  84.384000 ( 84.384000)
121.933000   0.000000 121.933000 (121.933000)
 85.533000   0.000000  85.533000 ( 85.532000)
 82.762000   0.000000  82.762000 ( 82.763000)
 82.090000   0.000000  82.090000 ( 82.090000)
 81.298000   0.000000  81.298000 ( 81.299000)
 80.774000   0.000000  80.774000 ( 80.773000)
Mean: 86.411200 SDev: 12.635700

(Hmm, I must have accidentally swapped in some large program in the middle of that JRuby run. The perils of benchmarking on a desktop machine. I don’t claim that the numbers are scientific, just illustrative!)

Fortunately, the fix again is very simple, and has previously been acknowledged. The latest (unreleased?) Hpricot has a new native extension, fast_xs, which is an almost drop-in replacement for the pure-ruby String#to_xs. (Almost, because it creates the method String#fast_xs instead of String#to_xs. ActiveSupport 2.0.2 and later take care of aliasing it for you). Unbeknownst to me, I ported fast_xs recently as part of upgrading JRuby extensions that have Java code in them. And so it happens to come in handy at this time. The patch for that is here.

I have the latest Hpricot gems on my server, so you can install it yourself (for either Ruby or JRuby):

gem install hpricot --source


jruby -S gem install hpricot --source

With that installed, the script now produces these results:

$ ruby to_xs.rb
  0.460000   0.080000   0.540000 (  0.537793)
  0.420000   0.070000   0.490000 (  0.501965)
  0.430000   0.070000   0.500000 (  0.501359)
  0.400000   0.070000   0.470000 (  0.484495)
  0.400000   0.070000   0.470000 (  0.479995)
  0.400000   0.070000   0.470000 (  0.469118)
  0.390000   0.070000   0.460000 (  0.468864)
  0.390000   0.070000   0.460000 (  0.465009)
  0.390000   0.060000   0.450000 (  0.452902)
  0.390000   0.070000   0.460000 (  0.466881)
Mean: 0.482838 SDev: 0.024926

$ jruby -J-server to_xs.rb 
  0.882000   0.000000   0.882000 (  0.883000)
  0.832000   0.000000   0.832000 (  0.832000)
  0.851000   0.000000   0.851000 (  0.850000)
  0.837000   0.000000   0.837000 (  0.837000)
  0.846000   0.000000   0.846000 (  0.846000)
  0.843000   0.000000   0.843000 (  0.843000)
  0.835000   0.000000   0.835000 (  0.835000)
  0.825000   0.000000   0.825000 (  0.826000)
  0.830000   0.000000   0.830000 (  0.830000)
  0.834000   0.000000   0.834000 (  0.833000)
Mean: 0.841500 SDev: 0.016379

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ActiveRecord-JDBC 0.6 Released!

Posted by Nick Sieger Tue, 06 Nov 2007 15:00:00 GMT

Just out is ActiveRecord-JDBC 0.6, the post-RubyConf release.

The sparkly new feature is Rails 2.0 support. In the soon-to-be-released Rails 2.0 (edge), Rails will automatically look for and load an adapter gem based on the name of the adapter you specify in database.yml. Example:

  adapter: funkdb

With this database configuration, Rails will attempt to load the activerecord-funkdb-adapter gem, require the active_record/connection_adapters/funkdb_adapter library, and call the method ActiveRecord::Base.funkdb_connection in order to obtain a connection to the database. (This is the mechanism used to off-load non-core adapters out of the Rails codebase.)

We can leverage this convention to make it easier than ever to get started using JRuby with your Rails application. So, the first thing new in the 0.6 release is the name. You now install activerecord-jdbc-adapter:

jruby -S gem install activerecord-jdbc-adapter

But wait, there’s more! We also have adapters for four open-source databases, including MySQL, PostgreSQL, and two embedded Java databases, Derby and HSQLDB. And, for your convenience, we’ve bundled the JDBC drivers in dependent gems, so you don’t have to go hunting them down if you don’t have them handy.

Check this out. Get a fresh copy of JRuby 1.0.2, unpack it, and add the bin directory to your path. Install the adapter:

$ jruby -S gem install activerecord-jdbcderby-adapter --include-dependencies
Successfully installed activerecord-jdbcderby-adapter-0.6
Successfully installed activerecord-jdbc-adapter-0.6
Successfully installed jdbc-derby-

In your Rails application, freeze to edge Rails (soon to be Rails 2.0).

rake rails:freeze:edge

Re-run the Rails command, regenerating configuration files.

jruby ./vendor/rails/railties/bin/rails .

Currently, Rails 2.0 uses openssl for the HMAC digest used in the new cookie session store, so we have to install the jruby-openssl gem:

jruby -S gem install jruby-openssl

Now, update your config/database.yml as follows:

  adapter: jdbcderby
  database: db/development

Re-run your migrations, and you should now see a Derby database footprint in the db/development directory.

$ ls -l db/development
total 24
-rw-r--r--    1 nicksieg  nicksieg    38 Nov  6 08:24 db.lck
-rw-r--r--    1 nicksieg  nicksieg     4 Nov  6 08:24 dbex.lck
drwxr-xr-x    5 nicksieg  nicksieg   170 Nov  6 08:24 log/
drwxr-xr-x   65 nicksieg  nicksieg  2210 Nov  6 08:24 seg0/
-rw-r--r--    1 nicksieg  nicksieg   882 Nov  6 08:24
drwxr-xr-x    2 nicksieg  nicksieg    68 Nov  6 08:24 tmp/

That’s it! To re-emphasize, to make your application run under JRuby, no longer will you need to a) find and download appropriate JDBC drivers, b) wonder where they should be placed so that JRuby will find them, or c) make custom changes to config/environment.rb. All that’s taken care of you if you use one of the following adapters:

  • activerecord-jdbcmysql-adapter (MySQL)
  • activerecord-jdbcpostgresql-adapter (PostgreSQL)
  • activerecord-jdbcderby-adapter (Derby)
  • activerecord-jdbchsqldb-adapter (HSQLDB)

If you need to connect to a different database, you’ll still need to place your database’s JDBC driver jar file in the appropriate place and use the straight activerecord-jdbc-adapter. Also note that in this case, and for Rails 1.2.x in general, you’ll still need to add that pesky require statement to config/environment.rb.

As always, there are bug fixes too (though we haven’t been tracking exactly which ones are fixed). We’re starting to file ActiveRecord-JDBC bugs in the JRuby JIRA now, and will be putting in future AR-JDBC versions to target soon too. So, please file new bugs in JIRA (and select component “ActiveRecord-JDBC”) rather than in the antiquated Rubyforge tracker.

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JRuby on Rails: Fast Enough

Posted by Nick Sieger Thu, 25 Oct 2007 03:36:00 GMT

People have been asking for a while how fast JRuby runs Rails. (Of course, “fast” has always been a relative term.) We haven’t been quick to answer the question, because frankly we didn’t know. We hadn’t been building real Rails applications on JRuby ourselves yet, and there was no definitive word from the crowd either.

Recently, several guys from ThoughtWorks have been working on a Rails petstore application and benchmark to get to the heart of the matter. Discussion has been heated on the JRuby mailing list, but results have not been conclusive yet.

In the project I’m working on, we’ve committed to using and deploying on JRuby. Eventually we were going to reach the point where we’d need to find out how well our application runs. So today I began running a simple single request benchmark on a relatively busy page. The numbers turned out to be rather surprising:



(The raw data is available here.)

Now, MRI (C Ruby) will always run about the same speed no matter how many runs you give it, but it’s well known that the JVM needs time to warm up. And indeed it does; after 250 iterations, Mongrel running on JRuby finally surpasses MRI. The JRuby/Goldspike/Glassfish combo comes close as well.

Some details about the setup:

  • I ran the tests on my MacBook Pro Core 2 Duo 2.4 GHz. I didn’t disable one of the cores for the tests, which means that JRuby has an advantage over MRI because it can use both (native threads at work). However, the test script ran the requests serially, which means that the advantage was minimal.
  • The application is indeed of the “hydra” variety; the setup is nearly identical to the second diagram on that page. So a single request is passing through not one, but two Rails applications in addition to touching the database. It rendered an HTML ERb view with data from an ActiveResource-accessed RESTful service. The applications are based on Rails 1.2.3.
  • MRI version is using Ruby 1.8.6 and Mongrel 1.0.1.
  • JRuby Mongrel is also version 1.0.1 (details on installing it here)
  • JRuby on Glassfish used Glassfish 2 and Goldspike 1.4, deployed in war files via Warbler.
  • The two JRuby setups used JDK 1.5 and were tweaked to disable ObjectSpace and use the “server” VM (-server argument to the JVM).

The main point I wish to make with these numbers is that JRuby performance is there today, and still has room to grow. There’s no longer any doubt in my mind. Yes, this is a simplistic application benchmark run on a developer’s machine, but it’s a real application. The test may not be exacting in precision, but I see enough in the numbers to believe that this will be replicable to production environments. The plot thickens!

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Gig: Speaking at RailsConf Europe 2007

Posted by Nick Sieger Fri, 14 Sep 2007 05:33:00 GMT

Speaking of keeping busy, I’ll be speaking alongside my colleague Craig McClanahan at RailsConf Europe in Berlin next week.

Sun is a Diamond Sponsor at RailsConf again, just like in Portland last May. Part of that sponsorship money pays for a brief keynote spot (filled by Craig) as well as a session or two. So no, I didn’t get my spot through an accepted proposal submission, but that doesn’t mean that the session is going to be a big marketing shill.

No, actually Craig and I are part of a small group at Sun that’s embracing Rails in a big way, and we’re going to be launching a site built mostly on Rails later this fall. We’re taking what we think are some novel approaches to building a Rails-based application and we thought we’d share some of those thoughts with you rather than drone on for the session about how great Sun is and what snazzy tools we make. (Although expect to see a subtle plug or two for Sun hardware and tools. Call it product placement rather than overt selling.)

I titled the session “Rails Hydra” because the central idea of the structure of our application is not one Rails app, but many. The UI and views don’t even talk to a database; instead they make use of ActiveResource and RESTful web services, talking to the models living in other Rails applications in the backend. One key point is we’re deploying .war files to JRuby running on Glassfish, thus avoiding headaches of morbidly multiplying Mongrel math. We’ll elaborate on this arrangement and talk about some of the other tools and tricks we’re using.

Also, Charlie, Tom and Ola will be there, so we’ll certainly have a JRuby summit at some point. Stop by and say hello!

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Warbler, A Little Birdie To Introduce Your Rails App To Java

Posted by Nick Sieger Tue, 04 Sep 2007 02:48:40 GMT

This week I was working on integrating the latest JRuby 1.0.1 and Goldspike 1.3 releases into our environment, when my frustration hit a fever pitch.

See, I had always thought that the .war packaging side of Goldspike was a little clunky and un-ruby-like, but I didn’t see a clear path to fixing it. I had heard little complaints about it here and there: the little configuration DSL didn’t give you enough control or wasn’t documented well enough; the fact that it downloads libraries from the internet during assembly (convenient, but not safe or reproducible for production deployments).

Also, in my own opinion it took the wrong approach to packaging Rails in a .war file. It puts the Rails application directory structure into the root of the .war file where any web server or Java application server might mistakenly serve up your code as static content. The Java .war file spec has this special directory called WEB-INF expressly for the purpose of hiding that stuff away, so why not use it?

And then, suddenly Goldspike was packaging up my entire Rails application directory, .svn directories and everything. So I set out to fix this once and for all.

And so I present Warbler. A little bird who chirpily steps up to the task of assembling your Rails application into a Java Web Archive (.war). Here, get it:

gem install warbler

And then, in the top directory of your Rails application,


Those two steps are all it takes to make a .war file, including your application and recent versions of JRuby and Goldspike, that’s deployable to your favorite Java application server.

There are a number of points about Warbler worth mentioning.

Does one thing, well

Warbler only packages, and doesn’t care about anything else, like how to dispatch servlet requests to Rails. This will allow for more runtime servlet binding mechanisms to take advantage of Warbler in the future.

Fast and lightweight

50% less code than the Goldspike packaging plugin, yet does the job quickly and efficiently.

Sane defaults

Warbler only packages code that you need to run the application, omitting database migrations and tests. If your application is self-sufficient (no external dependencies), then the out-of-the-box configuration will probably work for you. Public HTML/images/javascript/stylesheets go in the root of the webapp, where Java webservers expect them to be.

Documented, flexible configuration

Need to customize your configuration? Run warble config and edit config/warble.rb. All the options are there, commented and documented.

Need to change out the bundled JRuby/Goldspike versions? warble pluginize makes a copy of Warbler in the vendor/plugins area of your application, allowing you to change the .jar files in the vendor/plugins/warbler-0.9/lib directory. Warbler then makes his nest in your project’s list of rake tasks (as rake -T | grep war shows)

rake war            # Create trunk.war
rake war:app        # Copy all application files into the .war
rake war:clean      # Clean up the .war file and the staging area
rake war:gems       # Unpack all gems into WEB-INF/gems
rake war:jar        # Run the jar command to create the .war
rake war:java_libs  # Copy all java libraries into the .war
rake war:public     # Copy all public HTML files to the root of the .war
rake war:webxml     # Generate a web.xml file for the webapp

Warbler even omits himself in the .war file produced when running in plugin mode, since you won’t need him at runtime. It’s the little details that matter.

Give him a try and let me know if it makes your life deploying Rails applications to JRuby on Java appservers easier!

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geekSessions I: Ruby on Rails: To Scale or Not to Scale

Posted by Nick Sieger Wed, 23 May 2007 05:51:36 GMT

I was fortunate to be in town right after RailsConf and attended the inaugural geekSessions event on Rails scalibility. The event went off without a hitch: it was well attended, City Club is a classy place, and there was decent food and an open bar. I don’t know the SF geek/startup scene, but pretty much all of the few guys I know were there along with a ton of other folks. My only complaint would have been to let it run at least 30 minutes longer. Socializing was good too, but it seemed like the conversation was just getting started.

Here are some notes for you in my typical rapid-fire style -- hope they’re useful to you.

Ian McFarland

Case study: divine caroline


  • Load balancer
  • Apache + mongrel
  • MySQL
  • SOLR

Ruby is slow. Rails is slow. Unoptimized app was slow -- 7 pages/sec with ab. So how can Rails possibly be? 150 pv/s with a simple text render. This formed a sort of upper-bound, that ruled out fragment/action/partial caching, etc. This brought the throughput to 3500 pv/s. Except for page caching limitations:

  • Cache coherency
  • Writes are more expensive
  • Page caching is not applicable to as many pages as you think

But measure first. Pivotal built a drop-in page caching extension to deal with cache coherency issues (soon to be at

Jason Hoffman

Jason somehow has the distinction of the first four commits in the Rails repository. Joyent/TextDrive/Strongspace.

If your application is successful, you’re going to have a lot of machines. What happens when you have 1000s of machines, 100s of TB, 4 locations, etc. Is this really a Rails issue? In a typical Joyent setup, Rails is only one of 26+ processes on the server stack. So scaling it really doesn’t mean much more than scaling any application. Object creation in Ruby is fast, sockets and threads are slow. So forget sockets and threads.

Instead, use DNS, load balancers, evented mongrels, JRuby/Java, DBMSes (not just RDBMS; LDAP, filesystem, etc.), Rails process doing Rails only, static assets going through a static server, federate and separate as much as you can.

Jeremy LaTrasse

Jeremy’s job is about safety nets; about knowing the underlying infrastructure. Is the hardware/OS/stack important? Can you build safety nets around those so that you can spare cycles when you need to intrude into the system to troubleshoot?

Twitter is in a unique position with the volume of traffic to be able to find some pretty tough bugs, like the recent backtrace issue.

Bryan Cantrill

Measure first! Like Ian said. Is software information? Or a machine? It’s both. Nothing else in human existence can claim this. 3 weeks after Bryan joined Sun, he was working with Jeff (ZFS architect) debugging an issue when Jeff retorted, “Does it bother you that none of this exists? It’s just a representation of some plastic and metal morass in a backroom” (slightly paraphrased).

We’ve been living with bifurcated code -- “if DEBUG; print something” ad nauseum. But this has a cost. So dev code deviates from production code. But we can’t get the data we want, where it matters, in production. Bryan goes on to describe the aforementioned backtrace issue and how it saved Twitter 33% CPU. So don’t pre-optimize, but you’ve got to be prepared to go get the data. In production.

Q & A

What’s the best way to move from one database to two databases (MySQL), when you scale past the volume of reads that overwhelms one?

Jason doesn’t like the replication approach, it’s not fault tolerant. Reference to Dr Nic’s magic multi-connections gem. Reference to acts_as_readonly. Don’t rely on things that are out of your control, start reading/writing to multiple locations, at the application level. Jeremy: So do you want to be in the business of writing SQL or C extensions to Rails? What about MySQL proxy? Seems ok, but I might not trust it in production. MyTop/InnoTop will tell you about your query volume.

Virtualization: 4 virtual servers w/ web servers on top of a single physical server? Why?

Jason: Free BSD 4.9 on early pentium was the perfect balance of utilization. 18 CPUs by 64G RAM with virtual servers gets us back to that level of utilization. Bryan: Not all virtualization solutions are equivalent! (Solaris containers/zones plug.)

RDBMSes are not good for web applications? Why? Can you give some examples?

Jason: It depends on when you want to join. When people are clicking, or pre-assembled. Look at your application and put the data together before people request it. Why does YouTube need an RDBMS? It serves a file that people can comment on.

Mention of Dabble DB, ZFS, Jabber, Atom, Atom over Jabber, etc. as ways of innovative ways of storing objects, data, etc. GData/GCal most certainly does not store its Atom files in an RDBMS.

Sell Rails apps and have the customer deploy it? What options are available?

Ian: JRuby on Rails with a .war file is an interesting approach. What operational issues/ways to help with scaling remote deployments? Jeremy: Log files are the first line of defense. Jason: Corporate IT are comfortable with Java.

The pessimist in me says that my servers are going to fall over after 5 users. How can I be prepared/not be optimistic about a traffic spike?

Ian: Load test the crap out of the app. Find out the horizontal scaling point. Use solutions like S3 for images. Make sure you can scale by throwing hardware at it. Eventually single points of failure will overcome you (such as a single database), but you can wait until you get to that point before doing something about it.

Jason: You can benchmark your processes, and get an idea of what they can do. Most people that want to do something will be look at your stuff, and maybe signup. So front-load and optimize your signup process, possibly by taking it out of Rails.

Jeremy: Conversations with Zed, DHH, etc. have pointed out that sometimes “Rails isn’t good at that, take it out of Rails.” Same thing for the database. Split those things out into a different application.

Bryan: Do your dry land work, know your toolchain, so that when the moment comes, you can dive in and find the problem.

We have a migration that takes a week to run because of text processing. GC was running after every 10th DB statement. Used Rails bench GC patch to overcome the issue with the migration. Any issue running these?

Jason: We run those GC modifications and a few more in production, and they’re fine.

Most comversations revolve around items like database is slow, or Ruby is slow. How can we use DTrace to streamline the process?

Jeremy: We spent 20 minutes over lunch (plus some preparation) to find a Memcache issue. It’s worth it to spend a little time to learn the tool.

Bryan: “Awk is God’s gift to all of us.” When DTrace was being reviewed inside of Sun, folks commented “This reminds us of awk.” “Thanks!”

Jason: We’re putting a tracing plugin in Rails as a remote process to collect data from a running app. Apple has shown a commitment to get this in Leopard. Textual and graphical output are possible. I believe in DTrace a lot, and the tooling and documentation will go beyond its current state of an experts tool.

Lastly, what one closing thing would you like to say about Rails scalability?

Ian: Measure.
Jason: Don’t use relational databases.
Jeremy: I thought it was a Joyent sales pitch.
Bryan: Use DTrace (with Joyent accelerators of course).

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JRuby on Rails: Integration Plugin Goes 1.0

Posted by Nick Sieger Fri, 16 Mar 2007 16:55:00 GMT

On the heels of my last post, Robert announced the 1.0 release of Rails Integration, the bits that allow JRuby on Rails to be run out of a Java web archive (war). If you have any interest at all in trying out JRuby on Rails, do yourself a favor and try out the integration bits. Even though this is 1.0, we’re still moving rapidly and would appreciate any and all feedback. (And Robert is doing his best to keep up with changes in core.)

Related to this, Stuart Halloway recently announced his J plugin which is a drop-in collection of Rake tasks that bridge the inherent differences between Rails running on C Ruby vs. JRuby. We still have some work to do in some areas, such as database driver configuration, test database bootstrapping and launching unit tests. For example, instead of the big, ugly, database-specific case statement that’s in Rails’ databases.rake today:

desc "Recreate the test databases from the development structure"
task :clone_structure => [ "db:structure:dump", "db:test:purge" ] do
  abcs = ActiveRecord::Base.configurations
  case abcs["test"]["adapter"]
    when "mysql"
      ActiveRecord::Base.connection.execute('SET foreign_key_checks = 0')

").each do |table|
    when "postgresql"
      ENV['PGHOST']     = abcs["test"]["host"] if abcs["test"]["host"]
      ENV['PGPORT']     = abcs["test"]["port"].to_s if abcs["test"]["port"]
      ENV['PGPASSWORD'] = abcs["test"]["password"].to_s if abcs["test"]["password"]
      `psql -U "#{abcs["test"]["username"]}" -f db/#{RAILS_ENV}_structure.sql #{abcs["test"]["database"]}`
    when "sqlite", "sqlite3"
      dbfile = abcs["test"]["database"] || abcs["test"]["dbfile"]
      `#{abcs["test"]["adapter"]} #{dbfile} < db/#{RAILS_ENV}_structure.sql`
    when "sqlserver"
      `osql -E -S #{abcs["test"]["host"]} -d #{abcs["test"]["database"]} -i db\#{RAILS_ENV}_structure.sql`
    when "oci", "oracle"

").each do |ddl|
    when "firebird"
      db_string = firebird_db_string(abcs["test"])
      sh "isql -i db/#{RAILS_ENV}_structure.sql #{db_string}"
      raise "Task not supported by '#{abcs["test"]["adapter"]}'"

we can use migrations to create the test database:

desc "Recreate the test databases from migrations"
task :migrate_test_db do
  ActiveRecord::Schema.verbose = t.application.options.trace

Over time, I hope to see all these efforts coalesce and make the Rails developer experience virtually identical on either interpreter. What would be most excellent is to eventually push some of these improvements back to the Rails core.

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RSpec Autotest now a Rails Plugin

Posted by Nick Sieger Wed, 15 Nov 2006 15:46:00 GMT

Inspired by a posting on the RSpec list and recent comments stating that my Auto RSpec hack wasn’t working, I’ve bitten the bullet and upgraded to RSpec 0.7.2, and made rspec_autotest a plugin in the process. So, herewith are the necessary incantations to auto-rspec your project. If you’ve tried my hack already, please remove any bits you previously had installed.

  • Install RSpec on Rails, following the original instructions. As of RSpec 0.7.3, the specific version of ZenTest is no longer required. Also, diff-lcs is required to show unified diff output on should == failures.
gem install zentest -v 3.4.1
gem install diff-lcs
gem install rspec
script/plugin install svn://
  • Install rspec_autotest
script/plugin install
  • Start autotest
rake spec:autotest

Please let me know if you experience any problems!

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