{"action":"opened","issue":{"url":"https://api.github.com/repos/intel-hadoop/gearpump/issues/1231","labels_url":"https://api.github.com/repos/intel-hadoop/gearpump/issues/1231/labels{/name}","comments_url":"https://api.github.com/repos/intel-hadoop/gearpump/issues/1231/comments","events_url":"https://api.github.com/repos/intel-hadoop/gearpump/issues/1231/events","html_url":"https://github.com/intel-hadoop/gearpump/issues/1231","id":97471210,"number":1231,"title":"[Discussion] Support DAG with loops","user":{"login":"clockfly","id":2595532,"avatar_url":"https://avatars.githubusercontent.com/u/2595532?v=3","gravatar_id":"","url":"https://api.github.com/users/clockfly","html_url":"https://github.com/clockfly","followers_url":"https://api.github.com/users/clockfly/followers","following_url":"https://api.github.com/users/clockfly/following{/other_user}","gists_url":"https://api.github.com/users/clockfly/gists{/gist_id}","starred_url":"https://api.github.com/users/clockfly/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/clockfly/subscriptions","organizations_url":"https://api.github.com/users/clockfly/orgs","repos_url":"https://api.github.com/users/clockfly/repos","events_url":"https://api.github.com/users/clockfly/events{/privacy}","received_events_url":"https://api.github.com/users/clockfly/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-07-27T14:05:47Z","updated_at":"2015-07-27T14:05:47Z","closed_at":null,"body":"DAG with loop should not be called DAG :)\r\n\r\nWe see use cases that require a feedback channel. \r\nThe challengues will be:\r\n1. how to support the low watermark clock? As the clock is defined recursively?\r\n2. How to support back-pressure. DAG with loop can possiblely create a live-lock issue. With each processor wait for acks from other processor before sending acks."}}