Todd Huss

My hosted Linux server runs Debian Sarge 3.1 with Apache 2. As most Ruby users have heard Apache 2 is rumored to be problematic with FastCGI. This evening I’ve been working on putting up a new Ruby on Rails site and the deployment aspect had me a little worried. I already host a bunch of sites on the box (Java and PHP) and moving them all to Apache 1, Lighttpd, or Mongrel and then thoroughly testing them was a depressing prospect.
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I’ve often written scripts only to discover once added to crontab that it relies on an environment setting such as having the java command in the PATH or having CVSROOT set. To avoid this I now run scripts I’m developing for cron with env -i to simulate the script running without an environment as follows:

env -i somescript.sh

This has greatly increased my success rate of adding a script to cron and having it work from the get go.

In general when trying to write portable scripts don’t start them with #!/bin/bash, instead start them with #!/usr/bin/env bash. The only caveat is that you DO NOT want to do this for critical security scripts because it opens you up to path based exploits.
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My buddy Mike at UrbanaSoft is looking for an experienced full-time Unix and Windows sysadmin in downtown San Francisco. Pay is between $80-$100k depending on experience plus benefits and all that good stuff. If you’re qualified and interested or know someone that is email your resume to mike at urbanasoft dot com and mention that you learned about the job from my blog.

The biggest challege to moving large amounts of data into production with (almost) zero downtime with MySQL is that the old table will be dropped and the new table locked while you’re loading the data. If you try that while serving a lot of traffic you’ll get into trouble as the database connections start stacking up waiting for the lock to free on that table and then you’ll hit max connections giving most of your users a 500 error.

If you need to move big tables live you basically have 2 options: (more…)

When monitoring a production website (especially with a dozen or so application servers) you don’t want to rely on combining the logs and reviewing them manually for exceptions, you want the servers to notify you when there’s a problem. There are really 3 pieces to doing this properly and they are:
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I had quite a scare today when my new MacBook Pro wouldn’t boot. It would turn on, the screen would go white, and after about 20 seconds it flashed a question mark in a box on the screen. I thought it might have been related to a very minor drink spill incident (which resulted in my purchase of an iCurve stand) but it worked after the spill so I was a bit perplexed. I was not looking forward to going to the Apple store and parting with the laptop and getting charged a bundle so I opted for a little DIY troubleshooting.
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After upgrading Lighttpd to 1.4.11 from 1.4.8 it was no longer working with my Ruby on Rails project saying it couldn’t find public/dispatch.fcgi. Well, it turns out they made this security fix which breaks relative paths typically used in lighttpd.conf: (more…)

Eric Hodel posted their production website server setup over at the Robot Coop that handled 2.5M page views in a day not too long ago. I love this kind of information because it helps me get a feel for how we’re doing. At GreatSchools we serve around 900,000-980,000 page views on an average weekday, our record day was a bit above 3M page views, and siege load testing puts our cap around 4400 page views per minute.

The great thing about using siege is that we extract the load test from our access logs so that we can simulate real conditions. We size the hardware based on running at around 25% of our capacity on an average weekday which usually gives us just enough breathing room to handle a front page feature on Yahoo or AOL when those happen. (more…)

Is it just me or do you agree that we should be able to easily apply regular expression constraints to a column in a table without writing a stored procedure? For example if I want to guarantee that a varchar only contains alpha numeric characters with no spaces in most databases I currently have to write a stored procedure and use a trigger to call it on insert and update. Too much work for something that should be so simple!

Postgres is one of the few databases I’m aware of that currently solves the problem. You can see an example at Joseph Scott’s Blog of using a regex in a check constraint.

Sure, with Active Record in Ruby I can easily do this in code or in Java using the Hibernate validator but it’s a different story when you’ve got a database with multiple legacy applications and data loading systems running against it. In those cases the database if the final line of defense!

This is just a rant but I’m shocked that this situation hasn’t markedly improved over the past 10 years!