Rails 3.1: Intermittent 500 Internal Server Error when serving uncompressed assets

I'm upgrading an app to Rails 3.1. Quote often, Firebug will complain about some assets. Here are some errors pasted from Firebug:

"NetworkError: 500 Internal Server Error - http://unstilted.dev/assets/jquery-ui.js?body=1"
jquery...?body=1
"NetworkError: 500 Internal Server Error - http://unstilted.dev/assets/admin/pages/file_attachments.js"
file_a...ents.js
"NetworkError: 500 Internal Server Error - http://unstilted.dev/assets/admin/file_attachments/sortable.js?body=1"
sortab...?body=1
"NetworkError: 500 Internal Server Error - http://unstilted.dev/assets/jquery.js?body=1"

Refreshing the page would yield different assets showing the same error. When I copy and paste the URL I see the files just fine.

I'm using:

• Ubuntu 11.04
• Apache+Passenger 3.0.9

How do I fix this?

UPDATE: Log file

In this particular instance, jquery-ui.js was showing an error in Firebug. My log file looked like this:

Started GET "/assets/jquery.js?body=1" for 127.0.0.1 at Tue Sep 06 22:24:39 +0800 2011
Served asset /jquery.js - 304 Not Modified (0ms)


Started GET "/assets/jquery_ujs.js?body=1" for 127.0.0.1 at Tue Sep 06 22:24:39 +0800 2011


Started GET "/admin/site/sites/storage.js" for 127.0.0.1 at Tue Sep 06 22:24:39 +0800 2011
Served asset /jquery_ujs.js - 304 Not Modified (0ms)


Started GET "/assets/application.js?body=1" for 127.0.0.1 at Tue Sep 06 22:24:39 +0800 2011
  Processing by Admin::Site::SitesController#storage as JS
Served asset /application.js - 304 Not Modified (3ms)
  ...
Rendered admin/site/sites/storage.js.erb (0.1ms)
Completed 200 OK in 58ms (Views: 5.1ms | ActiveRecord: 21.1ms)


Started GET "/assets/admin/logo.png" for 127.0.0.1 at Tue Sep 06 22:24:39 +0800 2011
Served asset /admin/logo.png - 304 Not Modified (0ms)

It seems to have skipped jquery-ui.js!

UPDATE Oct 1, 2011:

I tried it out with the standalone passenger (passenger start) as it seems to give a more descriptive error. This is what happens when I try to load just the jquery.js file and press CTRL-R repeatedly to refresh my browser and load that asset repeatedly.

Started GET "/assets/jquery.js?body=1" for 127.0.0.1 at 2011-10-01 21:40:18 +0800
[ pid=29485 thr=3066030960 file=ext/nginx/HelperAgent.cpp:931 time=2011-10-01 21:40:18.691 ]: Uncaught exception in PassengerServer client thread:
   exception: Cannot read response from backend process: Connection reset by peer (104)
   backtrace:
     in 'void Client::forwardResponse(Passenger::SessionPtr&, Passenger::FileDescriptor&, const Passenger::AnalyticsLogPtr&)' (HelperAgent.cpp:603)
     in 'void Client::handleRequest(Passenger::FileDescriptor&)' (HelperAgent.cpp:857)
     in 'void Client::threadMain()' (HelperAgent.cpp:950)

2011/10/01 21:40:18 [error] 29522#0: *16 upstream prematurely closed connection while reading response header from upstream, client: 127.0.0.1, server: _, request: "GET /assets/jquery.js?body=1 HTTP/1.1", upstream: "passenger:unix:/passenger_helper_server:", host: "get.unstilted.dev:3000"
[ pid=29674 thr=78131090 file=utils.rb:176 time=2011-10-01 21:40:18.699 ]: *** Exception PGError in application (server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.
) (process 29674, thread #<Thread:0x9505f24>):
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:276:in `exec'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:276:in `block in clear_cache!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:275:in `each_value'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:275:in `clear_cache!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/postgresql_adapter.rb:303:in `disconnect!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:202:in `block in disconnect!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:201:in `each'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:201:in `disconnect!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activesupport-3.1.0/lib/active_support/core_ext/module/synchronization.rb:35:in `block in disconnect_with_synchronization!'
        from /home/ramon/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/monitor.rb:201:in `mon_synchronize'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activesupport-3.1.0/lib/active_support/core_ext/module/synchronization.rb:34:in `disconnect_with_synchronization!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:395:in `block in clear_all_connections!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:395:in `each_value'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:395:in `clear_all_connections!'
        from /home/ramon/.rvm/gems/ruby-1.9.2-p290@unstilted/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_specification.rb:123:in `clear_all_connections!'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/utils.rb:398:in `before_handling_requests'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/rack/application_spawner.rb:204:in `start_request_handler'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/rack/application_spawner.rb:170:in `block in handle_spawn_application'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/utils.rb:479:in `safe_fork'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/rack/application_spawner.rb:165:in `handle_spawn_application'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/abstract_server.rb:357:in `server_main_loop'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/abstract_server.rb:206:in `start_synchronously'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/abstract_server.rb:180:in `start'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/rack/application_spawner.rb:128:in `start'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/spawn_manager.rb:253:in `block (2 levels) in spawn_rack_application'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/abstract_server_collection.rb:132:in `lookup_or_add'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/spawn_manager.rb:246:in `block in spawn_rack_application'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/abstract_server_collection.rb:82:in `block in synchronize'
        from <internal:prelude>:10:in `synchronize'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/abstract_server_collection.rb:79:in `synchronize'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/spawn_manager.rb:244:in `spawn_rack_application'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/spawn_manager.rb:137:in `spawn_application'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/spawn_manager.rb:275:in `handle_spawn_application'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/lib/phusion_passenger/abstract_server.rb:357:in `server_main_loop'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/l开发者_开发技巧ib/phusion_passenger/abstract_server.rb:206:in `start_synchronously'
        from /home/ramon/.passenger/standalone/3.0.9-x86-ruby1.9.2-linux-gcc4.5.2-1002/support/helper-scripts/passenger-spawn-server:99:in `<main>'
Served asset /jquery.js - 304 Not Modified (0ms)
cache: [GET /assets/jquery.js?body=1] stale, valid, store
[ pid=29485 thr=3064224624 file=ext/nginx/HelperAgent.cpp:921 time=2011-10-01 21:40:18.734 ]: Couldn't forward the HTTP response back to the HTTP client: It seems the user clicked on the 'Stop' button in his browser.

The problem is in the middle of Passenger and Rails 3.1 PostgreSQL adapter. According to this issue https://github.com/rails/rails/issues/1339 Rails 3.1.1.rc1 should have this issue fixed.

Also stop using PassengerSpawnMethod conservative because it makes Passenger & eventually REE performance optimizations useless - it spawns separate Rails instances - no sharing of common code.

I had the same issue. For me I think it was some cached assets or something.

I ran

rake assets:clean 

and then requested the page again. This generated real error messages I could use to debug.

It turned out that one of my JS files still had the old require syntax with <>s.

Hope this solves your problem too, I know it was frustrating!

The quick fix is to tell passenger to use the 'conservative' spawn method.

in your apache2.conf

PassengerSpawnMethod conservative