第一次运行Rails应用程序时抛出数据库错误，重新加载时可以正常运行

Question

I think this all started around the time my host (Bluehost) upgraded their RoR to version 3.

The first time I run my app after a hours of it not being accessed it throws an error (see below). If I reload, the error goes away and the database access works as expected.

I thought it might be the version of ActiveRecord, but it looks as if the Bluehost is using its own version (3.2.13) and not the version I installed in my config (4.2.1).

I suspect it might be something to do with Phusion Passenger and caching connections, but I'm not sure how to diagnose or fix that.

Any pointers greatly appreciated.

According to command line:

Ruby version: 1.9.3p429 Rails version: 3.2.13

Connecting to database specified by database.yml
Started GET "/" for xx.xx.xx.xxx at 2015-04-30 17:00:52 -0600

TypeError (can't convert nil into String):
  mysql2 (0.3.11) lib/mysql2/client.rb:20:in `init_connection'
  mysql2 (0.3.11) lib/mysql2/client.rb:20:in `initialize'
  activerecord (3.2.13) lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `new'
  activerecord (3.2.13) lib/active_record/connection_adapters/mysql2_adapter.rb:16:in `mysql2_connection'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:315:in `new_connection'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:325:in `checkout_new_connection'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:247:in `block (2 levels) in checkout'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `loop'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:242:in `block in checkout'
  /usr/lib64/ruby/1.9.3/monitor.rb:211:in `mon_synchronize'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:239:in `checkout'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:102:in `block in connection'
  /usr/lib64/ruby/1.9.3/monitor.rb:211:in `mon_synchronize'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:101:in `connection'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:410:in `retrieve_connection'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_specification.rb:171:in `retrieve_connection'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in `connection'
  activerecord (3.2.13) lib/active_record/query_cache.rb:61:in `call'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
  activesupport (3.2.13) lib/active_support/callbacks.rb:405:in `_run__3881617127537431469__call__281038867919454016__callbacks'
  activesupport (3.2.13) lib/active_support/callbacks.rb:405:in `__run_callback'
  activesupport (3.2.13) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
  activesupport (3.2.13) lib/active_support/callbacks.rb:81:in `run_callbacks'
  actionpack (3.2.13) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
  railties (3.2.13) lib/rails/rack/logger.rb:32:in `call_app'
  railties (3.2.13) lib/rails/rack/logger.rb:16:in `block in call'
  activesupport (3.2.13) lib/active_support/tagged_logging.rb:22:in `tagged'
  railties (3.2.13) lib/rails/rack/logger.rb:16:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/request_id.rb:22:in `call'
  rack (1.4.5) lib/rack/methodoverride.rb:21:in `call'
  rack (1.4.5) lib/rack/runtime.rb:17:in `call'
  activesupport (3.2.13) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
  rack (1.4.5) lib/rack/lock.rb:15:in `call'
  rack-cache (1.2) lib/rack/cache/context.rb:136:in `forward'
  rack-cache (1.2) lib/rack/cache/context.rb:245:in `fetch'
  rack-cache (1.2) lib/rack/cache/context.rb:185:in `lookup'
  rack-cache (1.2) lib/rack/cache/context.rb:66:in `call!'
  rack-cache (1.2) lib/rack/cache/context.rb:51:in `call'
  railties (3.2.13) lib/rails/engine.rb:479:in `call'
  railties (3.2.13) lib/rails/application.rb:223:in `call'
  railties (3.2.13) lib/rails/railtie/configurable.rb:30:in `method_missing'
  /etc/httpd/modules/passenger/lib/phusion_passenger/rack/request_handler.rb:97:in `process_request'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_request_handler.rb:520:in `accept_and_process_next_request'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_request_handler.rb:274:in `main_loop'
  /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb:206:in `start_request_handler'
  /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb:171:in `block in handle_spawn_application'
  /etc/httpd/modules/passenger/lib/phusion_passenger/utils.rb:470:in `safe_fork'
  /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb:166:in `handle_spawn_application'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb:357:in `server_main_loop'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb:206:in `start_synchronously'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb:180:in `start'
  /etc/httpd/modules/passenger/lib/phusion_passenger/rack/application_spawner.rb:129:in `start'
  /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb:253:in `block (2 levels) in spawn_rack_application'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server_collection.rb:132:in `lookup_or_add'
  /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb:246:in `block in spawn_rack_application'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server_collection.rb:82:in `block in synchronize'
  <internal:prelude>:10:in `synchronize'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server_collection.rb:79:in `synchronize'
  /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb:244:in `spawn_rack_application'
  /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb:137:in `spawn_application'
  /etc/httpd/modules/passenger/lib/phusion_passenger/spawn_manager.rb:275:in `handle_spawn_application'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb:357:in `server_main_loop'
  /etc/httpd/modules/passenger/lib/phusion_passenger/abstract_server.rb:206:in `start_synchronously'
  /etc/httpd/modules/passenger/helper-scripts/passenger-spawn-server:99:in `<main>'

Answer 1

it looks as if the Bluehost is using its own version (3.2.13) and not the version I installed in my config (4.2.1)

If this is really the case, that your hosting provider is using Rails 3.2.13 when you've specified 4.2.1 in your Gemfile / Gemfile.lock then get a new hosting provider, and for two reasons.

First, obviously, you need to be able to ship the version of the app that you know works locally.

Second, any hosting provider who has 3.2.13 as the default Rails version should go out of business immediately. There are security issues fixed in the patches up to 3.2.21 and the whole 3.2 series is no longer supported for any fixes except the most severe security issues.

In summary - I suspect that your problem is being caused by the hosting provider's configuration. Maybe talk to them to see if there's some mis-configuration for your app/server, otherwise move to someone else.