{"action":"created","issue":{"url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/issues/227","labels_url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/issues/227/labels{/name}","comments_url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/issues/227/comments","events_url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/issues/227/events","html_url":"https://github.com/rabbitmq/rabbitmq-server/issues/227","id":96349947,"number":227,"title":"rabbit_queue_index:maybe_flush_journal/2 significantly reduces performance when called.","user":{"login":"videlalvaro","id":30834,"avatar_url":"https://avatars.githubusercontent.com/u/30834?v=3","gravatar_id":"","url":"https://api.github.com/users/videlalvaro","html_url":"https://github.com/videlalvaro","followers_url":"https://api.github.com/users/videlalvaro/followers","following_url":"https://api.github.com/users/videlalvaro/following{/other_user}","gists_url":"https://api.github.com/users/videlalvaro/gists{/gist_id}","starred_url":"https://api.github.com/users/videlalvaro/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/videlalvaro/subscriptions","organizations_url":"https://api.github.com/users/videlalvaro/orgs","repos_url":"https://api.github.com/users/videlalvaro/repos","events_url":"https://api.github.com/users/videlalvaro/events{/privacy}","received_events_url":"https://api.github.com/users/videlalvaro/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/labels/bug","name":"bug","color":"fc2929"},{"url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/labels/effort-medium","name":"effort-medium","color":"5080b8"},{"url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/labels/enhancement","name":"enhancement","color":"009800"}],"state":"open","locked":false,"assignee":{"login":"michaelklishin","id":1090,"avatar_url":"https://avatars.githubusercontent.com/u/1090?v=3","gravatar_id":"","url":"https://api.github.com/users/michaelklishin","html_url":"https://github.com/michaelklishin","followers_url":"https://api.github.com/users/michaelklishin/followers","following_url":"https://api.github.com/users/michaelklishin/following{/other_user}","gists_url":"https://api.github.com/users/michaelklishin/gists{/gist_id}","starred_url":"https://api.github.com/users/michaelklishin/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/michaelklishin/subscriptions","organizations_url":"https://api.github.com/users/michaelklishin/orgs","repos_url":"https://api.github.com/users/michaelklishin/repos","events_url":"https://api.github.com/users/michaelklishin/events{/privacy}","received_events_url":"https://api.github.com/users/michaelklishin/received_events","type":"User","site_admin":false},"milestone":null,"comments":2,"created_at":"2015-07-21T15:44:08Z","updated_at":"2015-08-14T20:06:46Z","closed_at":null,"body":"See this thread for more details: https://groups.google.com/forum/#!searchin/rabbitmq-users/raymond/rabbitmq-users/HHrH4I2bVjs/N7IoYB9G4oMJ"},"comment":{"url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/issues/comments/131224146","html_url":"https://github.com/rabbitmq/rabbitmq-server/issues/227#issuecomment-131224146","issue_url":"https://api.github.com/repos/rabbitmq/rabbitmq-server/issues/227","id":131224146,"user":{"login":"gmr","id":49469,"avatar_url":"https://avatars.githubusercontent.com/u/49469?v=3","gravatar_id":"","url":"https://api.github.com/users/gmr","html_url":"https://github.com/gmr","followers_url":"https://api.github.com/users/gmr/followers","following_url":"https://api.github.com/users/gmr/following{/other_user}","gists_url":"https://api.github.com/users/gmr/gists{/gist_id}","starred_url":"https://api.github.com/users/gmr/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/gmr/subscriptions","organizations_url":"https://api.github.com/users/gmr/orgs","repos_url":"https://api.github.com/users/gmr/repos","events_url":"https://api.github.com/users/gmr/events{/privacy}","received_events_url":"https://api.github.com/users/gmr/received_events","type":"User","site_admin":false},"created_at":"2015-08-14T20:06:46Z","updated_at":"2015-08-14T20:06:46Z","body":"I'm thinking this might be even more significant the larger the amount of data. In my production issue today my consumers could not keep up with the publishing velocity. Messages are generally >50KB, but can be larger. Consumers would only be delivered at a rate that was roughly the disk read rate, *but* there was no IOWait on any node in the cluster. So where I might be able to go @1k per sec, when it was ~20GB in size on disk, it was in the 10s per second. When it was ~1GB on disk, it started to go back to normal speeds\r\n\r\nAnother way to state it was the disk read rate was disproportionately slow, the larger the transient message store became, without any indicators in the OS as to why (other than RAM usage?).\r\n\r\n![Big data, slow performance](http://i.imgur.com/z50UcxV.png)"}}