Resque 工作人员中的间歇性“Moped::Protocol::Command failed with error nil”错误

Question

我正在使用 Rails 3.2、Mongoid 3.1.7、Moped 1.5.3 和 Resque 1.24.1

我的 Resque 工作人员反复收到“Moped::Protocol::Command failed with error nil”[1] 错误。

Moped 存储库中的This issue 和 this one 让我认为这可能是由于 Resque 分叉，但它们都是关于旧版本的 Moped，我一直无法找到任何特定于配置 Resque 以与 Mongoid 完美配合的特定信息。

如何解决我的 Resque 工作人员中的错误？

[1] 完全错误： Exception: Moped::Errors::OperationFailure Error: The operation: #<Moped::Protocol::Command @length=58 @request_id=3 @response_to=0 @op_code=2004 @flags=[] @full_collection_name="admin.$cmd" @skip=0 @limit=-1 @selector={:ismaster=>1} @fields=nil> failed with error nil /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:99:in `block in command' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:600:in `[]' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:600:in `block (3 levels) in flush' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:599:in `map' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:599:in `block (2 levels) in flush' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:150:in `ensure_connected' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:595:in `block in flush' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:610:in `logging' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:594:in `flush' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:583:in `process' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:92:in `command' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/node.rb:409:in `refresh' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/cluster.rb:171:in `block in refresh' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/cluster.rb:185:in `each' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/cluster.rb:185:in `refresh' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/cluster.rb:135:in `nodes' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/cluster.rb:206:in `with_primary' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/session/context.rb:108:in `with_node' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/cursor.rb:137:in `load_docs' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/cursor.rb:25:in `each' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/query.rb:76:in `each' /shared/bundle/ruby/2.2.0/gems/moped-1.5.3/lib/moped/query.rb:76:in `each' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/contextual/mongo.rb:423:in `entries' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/contextual/mongo.rb:423:in `check_existence' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/contextual/mongo.rb:146:in `exists?' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/contextual.rb:19:in `exists?' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/validations/uniqueness.rb:273:in `validate_root' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/validations/uniqueness.rb:52:in `block in validate_each' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/validations/queryable.rb:23:in `with_query' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/validations/uniqueness.rb:46:in `validate_each' /shared/bundle/ruby/2.2.0/gems/activemodel-3.2.22/lib/active_model/validator.rb:153:in `block in validate' /shared/bundle/ruby/2.2.0/gems/activemodel-3.2.22/lib/active_model/validator.rb:150:in `each' /shared/bundle/ruby/2.2.0/gems/activemodel-3.2.22/lib/active_model/validator.rb:150:in `validate' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:310:in `_callback_before_265' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:418:in `_run__123721054543109017__validate__3207805434451540367__callbacks' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:405:in `__run_callback' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:385:in `_run_validate_callbacks' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:81:in `run_callbacks' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/callbacks.rb:130:in `run_callbacks' /shared/bundle/ruby/2.2.0/gems/activemodel-3.2.22/lib/active_model/validations.rb:228:in `run_validations!' /shared/bundle/ruby/2.2.0/gems/activemodel-3.2.22/lib/active_model/validations/callbacks.rb:53:in `block in run_validations!' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:403:in `_run__123721054543109017__validation__3207805434451540367__callbacks' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:405:in `__run_callback' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:385:in `_run_validation_callbacks' /shared/bundle/ruby/2.2.0/gems/activesupport-3.2.22/lib/active_support/callbacks.rb:81:in `run_callbacks' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/callbacks.rb:130:in `run_callbacks' /shared/bundle/ruby/2.2.0/gems/activemodel-3.2.22/lib/active_model/validations/callbacks.rb:53:in `run_validations!' /shared/bundle/ruby/2.2.0/gems/activemodel-3.2.22/lib/active_model/validations.rb:195:in `valid?' /shared/bundle/ruby/2.2.0/gems/mongoid-3.1.7/lib/mongoid/validations.rb:84:in `valid?' /releases/20160315172839/app/performers/garmin_receive_push.rb:11:in `block in perform' /releases/20160315172839/app/performers/garmin_receive_push.rb:9:in `map' /releases/20160315172839/app/performers/garmin_receive_push.rb:9:in `perform'

Answer 1

这似乎奏效了。在过去 18 小时内，我的 Resque 工作人员中的错误从昨天的 30 多个变为 0。

添加到我的 Resque 配置中：

Resque.before_fork do
    ::Mongoid.default_session.disconnect
end

我对这里出了什么问题没有一个非常连贯的描述。 Resque Workers fork 一个子进程，然后子进程处理作业，所以我目前的操作假设是，这类似于链接问题中描述的 Unicorn 和Passenger forking 的问题。