Threading issues with Puma

Started seeing these:

```#
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/aws-xray-sdk-0.11.2/lib/aws-xray-sdk/sampling/default_sampler.rb:85:in `process_matched_rule'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/aws-xray-sdk-0.11.2/lib/aws-xray-sdk/sampling/default_sampler.rb:54:in `sample_request?'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/aws-xray-sdk-0.11.2/lib/aws-xray-sdk/facets/helper.rb:36:in `should_sample?'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/aws-xray-sdk-0.11.2/lib/aws-xray-sdk/facets/rack.rb:30:in `call'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/puma-4.0.1/lib/puma/configuration.rb:228:in `call'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/puma-4.0.1/lib/puma/server.rb:657:in `handle_request'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/puma-4.0.1/lib/puma/server.rb:467:in `process_client'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/puma-4.0.1/lib/puma/server.rb:328:in `block in run'
/usr/local/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/puma-4.0.1/lib/puma/thread_pool.rb:135:in `block in spawn_thread'```

However we aren't using sampling so I'm not sure whats up.