CLONE - autoload not threadsafe

The fix for #3194 appears to be incomplete. I have updated to 1.6.7.2, and received the following greeting upon entering the threaded part of my application:

ArgumentError: While processing family 49: ServiceBilling is not missing constant IndividualBilling!
load_missing_constant at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:417

Note that I was just as often seeing the error that Yehuda reported as this one on jruby versions through 1.6.5.

This may or may not be related to autoload thread-safety. Rails uses several interesting mechanisms for loading, autoloading, and reloading code.

I'm fairly confident that the autoload logic in 1.6.7 is thread-safe, in that two threads will never autoload, and if two attempt the same autoload at the same time the second will block until the first completes. That doesn't necessarily mean that all loading concurrency issues are solved, especially if Rails is routing around autoload in some scenarios. For example, concurrent requires are still as risky as ever.

Could you try passing -Xglobal.require.lock=true to JRuby, either at command line or via JRUBY_OPTS env var?

We need more digging to figure out whether there's something we can fix.

RAILS_ENV=production jruby -J-Xmx10240m -Xglobal.require.lock=true -rconfig/boot -rcommands/runner -e production "Physical::Utility ...

Took a couple of tries, but got a good pair:

LoadError: While processing family 23: Expected /var/www/apps/bpm_service/releases/20120329205747/lib/service_billing/individual_primary_care_service_billing_info.rb to define Se
rviceBilling::IndividualPrimaryCareServiceBillingInfo load_missing_constant at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:426
const_missing_with_dependencies at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:80 load_missing_constant at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:437
const_missing at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:96
...

From a separate thread:
ArgumentError: While processing family 56: ServiceBilling is not missing constant PossibleEndDate!
load_missing_constant at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:417
const_missing_with_dependencies at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:80
send at org/jruby/RubyKernel.java:2080
const_missing at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:98
const_missing at /var/www/apps/bpm_service/shared/bundle/jruby/1.8/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:96

Unless I didn't pass the option in properly.

Note: adding lib to config.eager_load_paths takes care of the problem.

Charles mentioned concurrent requires being risky, and I think that's the bottom line here. load_missing_constant calls require_or_load, which definitely can lead to a concurrent require. Not sure about the performance hit of mutexing that method.

Nathan: Sorry we didn't circle back to this before 1.7 final.

It looks like your command line is correct, but I still think this is a Rails problem. They do not use autoload to trigger the require_or_load, and it still seems like this is a case where Rails is failing to properly load these libraries safely. I want to help you but I think we might want to spin this back toward the Rails folks.