Deciphering Apache error messages and other pleasant pastimes

There comes a dreaded time in every developer’s life when the inevitable happens – you are forced to switch to a new machine, and re-configure the entire dev environment you spent months (or years, in my case) tweaking and perfecting.  For me, that time unexpectedly came last week when the hard disk on my laptop decided it was time for a winter holiday.

Armed with a reimaged laptop and Redfin’s internal developer machine setup guide, I was making decent progress until I hit a stumbling block: Apache was crashing. No matter what I did – on the first browser hit, I was greeted with a friendly error:

The Event Log had a slightly more descriptive message:

Faulting application Apache.exe, version 2.0.63.200, faulting module ntdll.dll, version 5.1.2600.2180, fault address 0x00011e58.

Apache’s error log was mysterious in its own way:

[notice]  Parent: child process exited with status 3221225477 -- Restarting.

To save you hours of debugging, hair pulling, reinstalling, and commenting out of httpd.conf that I went through, I’ll just point you directly to the root cause of the problem:  https://issues.apache.org/bugzilla/show_bug.cgi?id=44338: mod_deflate crashes and does not return response.  If you have Apache 2.0.63 on Windows, are loading the mod_deflate.so module, and are using it by including AddOutputFilterByType/SetOutputFilter directives in your httpd.conf – Apache will crash.  Currently there is no fix for this (although the bug above may be updated with a fix in the future) – you have a choice of taking out mod_deflate out of your Apache config, or upgrading to Apache 2.2.

Since mod_deflate is not essential in our developer setup, I happily chose the former option and got my Apache up and running.

A Virtual Earth to Google Maps Transition: From Idea to Deployment In a Few Weeks

Whenever I out myself as a member of the Redfin search team to someone who has used Redfin, one of the first questions I get is, “so why do you guys use the Microsoft Map?  Why didn’t you choose Google?”.  The full answer is a bit long, but the short answer is easy: speed.

Every few months, we’ve tested Google Maps against Virtual Earth, and the result was always the same: Google’s script and tiles loaded considerably faster, but Virtual Earth was as much as four times faster at adding a ton of items to the map.  Since our user interface can add up to 500 houses at a time to a map, we just felt like Google wasn’t able to give us the performance we needed.  To be fair, part of VE’s speed was due to a bulk add feature that we had lobbied for them to put in, but it worked well, and so we put Google aside, wistfully looking at those speedy script and tile load times.

A few months ago, though, we started contract renegotiations with Microsoft, and we decided to give Google Maps a closer look.  One of my colleagues, the brilliant Dan Fabulich of Selenium fame, figured out that we could code our own custom GOverlay to make Google Maps display items much faster than it had previously.  The question then became: how hard would it be to port our site from one platform to the other?  And would it be worth it to do so? Read the rest of this entry »