{"action":"closed","issue":{"url":"https://api.github.com/repos/Blizzard/node-rdkafka/issues/140","repository_url":"https://api.github.com/repos/Blizzard/node-rdkafka","labels_url":"https://api.github.com/repos/Blizzard/node-rdkafka/issues/140/labels{/name}","comments_url":"https://api.github.com/repos/Blizzard/node-rdkafka/issues/140/comments","events_url":"https://api.github.com/repos/Blizzard/node-rdkafka/issues/140/events","html_url":"https://github.com/Blizzard/node-rdkafka/issues/140","id":212844359,"number":140,"title":"Subscribing to unknown topic","user":{"login":"Pchelolo","id":814754,"avatar_url":"https://avatars0.githubusercontent.com/u/814754?v=3","gravatar_id":"","url":"https://api.github.com/users/Pchelolo","html_url":"https://github.com/Pchelolo","followers_url":"https://api.github.com/users/Pchelolo/followers","following_url":"https://api.github.com/users/Pchelolo/following{/other_user}","gists_url":"https://api.github.com/users/Pchelolo/gists{/gist_id}","starred_url":"https://api.github.com/users/Pchelolo/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Pchelolo/subscriptions","organizations_url":"https://api.github.com/users/Pchelolo/orgs","repos_url":"https://api.github.com/users/Pchelolo/repos","events_url":"https://api.github.com/users/Pchelolo/events{/privacy}","received_events_url":"https://api.github.com/users/Pchelolo/received_events","type":"User","site_admin":false},"labels":[],"state":"closed","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":5,"created_at":"2017-03-08T20:16:38Z","updated_at":"2017-03-16T16:54:37Z","closed_at":"2017-03-16T16:54:37Z","body":"In case the topic doesn't exist and a consumer subscribes to it, there's no easy way to find out that the topic is not there except making a call to fetch the metadata before attempting to subscribe.\r\n\r\nFurthermore, consuming from such a consumer returns ERR_TIMEOUT as if the topic existed, but there were no activity in there. \r\n\r\nBut the biggest problem is that when the topic gets created and message start flowing there, the consumer that's subscribed before topic creation will never receive these messages nor would it indicate any issue.\r\n\r\nI'm not quite sure how to deal with this. Creating the topic by default with default parameters seem dangerous since it can easily go unnoticed, throwing an error on attempt to subscribe/consume might be a nice feature, `kafkacat` does that for example. Tracking whether the topic existence have changed and re-subscribing to start receiving messages once the topic was created could also be an option. Not sure which option is better, but silently ignoring the error is definitely worse then any of them. \r\n\r\nWould be nice know your opinion on this before deciding how to deal with topic creation in our environment."}}
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