将Phusion Passenger从3.0.11更新到4.0.10会导致ActiveRecord :: StatementInvalid查询期间与MySQL服务器的连接断开

Question

I'm trying to update a rails application on our production server to ruby 1.9. We have several production sites, some of which have more critical uptime requirements so it would be really beneficial to update each site one at a time to ensure the least amount of downtime on the more critical sites.

Phusion Passenger 4 allows to easily run sites using different ruby versions which would be great functionality for ensuring a staggered transition to 1.9 (and later 2.0). Currently the server is working under Apache module Passenger 3.0.11 and using the system ruby-1.8.7-352.

To start the update I have installed rvm and ruby-1.9.2-p320. Using the new ruby I install passenger 4.0.10. I then updated the httpd.conf with:

LoadModule passenger_module /path/to/mod_passenger.so
PassengerRoot /path/to/gems/passenger-4.0.10
PassengerDefaultRuby /path/to/ruby-1.9.2-p320/ruby

Then in the site.conf

PassengerRuby /path/to/old/ruby

This means that the sites should be using the system ruby, just as before, and the only thing to be updated is Phusion Passenger. The result is that the production applications have started throwing ActiveRecord::StatementInvalid exceptions maybe once every 3000 requests. The exception rate is obviously higher during high traffic periods. The error is as follows:

Exception Class: ActiveRecord::StatementInvalid
Message: Mysql2::Error: Lost connection to MySQL server during query: SELECT ...

I have example of the error on several pages but mostly on those with "large" sql queries (maybe up to 0.4 second query, 1.7 sec request).

I have since restored the httpd.conf with the old passenger and the errors have ceased.

Can anyone help diagnose the source of the query deaths?

Thanks.

=== Edit 1 ===

I've tried adding PassengerSpawnMethod direct to httpd.conf so it now reads:

LoadModule passenger_module /path/to/mod_passenger.so
PassengerRoot /path/to/gems/passenger-4.0.10
PassengerDefaultRuby /path/to/ruby-1.9.2-p320/ruby
PassengerSpawnMethod direct

but still have the same error occurring with seemingly the same frequency.

=== Edit 2 ===

I've also tried out of desperation installing passenger 4.0.10 under the system 1.8 ruby with the same results. Is there anything more I can do or should I just assume passenger isn't ready to be updated? Is there anything I can look for in my code that could be causing this? I've checked mysql error logs and there's nothing. Can anyone suggest anything else worth looking at? As for moving forward I'm not planning to spend much more time on this, I'll be testing the production site under ruby 1.9 over weekends and just bite the bullet and move them all over under passenger 3.

=== Edit 3 ===

I've now setup passenger so there is only one passenger process for each application under passenger 4. There are still these errors! So not a spawning/multiple access problem. I can't see passenger messing with the application connection to the db but passenger is the only thing I'm changing. I'm using the standard msyql2 gem for my rails app. The requests that are failing are largish select queries (on the order of a second to complete).

Answer 1

Having updated my apps to ruby 1.9 the errors have ceased. I never found out what was causing them but I wanted to answer here in case anyone else runs into the same problem.

Answer 2

I had the same issue, but not with phusion. Turned out these "larger" queries were being killed by the ActiveRecord connection pool reaper ( reaping_frequency config). See: https://stackoverflow.com/a/22423893/72176

Not sure if this is your issue as it seems yours fixed itself, but if others have this error message – that is definitely one avenue to check.