{"action":"opened","issue":{"url":"https://api.github.com/repos/goldshtn/msos/issues/11","labels_url":"https://api.github.com/repos/goldshtn/msos/issues/11/labels{/name}","comments_url":"https://api.github.com/repos/goldshtn/msos/issues/11/comments","events_url":"https://api.github.com/repos/goldshtn/msos/issues/11/events","html_url":"https://github.com/goldshtn/msos/issues/11","id":93762219,"number":11,"title":"Heap indexing","user":{"login":"goldshtn","id":1685437,"avatar_url":"https://avatars.githubusercontent.com/u/1685437?v=3","gravatar_id":"","url":"https://api.github.com/users/goldshtn","html_url":"https://github.com/goldshtn","followers_url":"https://api.github.com/users/goldshtn/followers","following_url":"https://api.github.com/users/goldshtn/following{/other_user}","gists_url":"https://api.github.com/users/goldshtn/gists{/gist_id}","starred_url":"https://api.github.com/users/goldshtn/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/goldshtn/subscriptions","organizations_url":"https://api.github.com/users/goldshtn/orgs","repos_url":"https://api.github.com/users/goldshtn/repos","events_url":"https://api.github.com/users/goldshtn/events{/privacy}","received_events_url":"https://api.github.com/users/goldshtn/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/goldshtn/msos/labels/new%20feature","name":"new feature","color":"84b6eb"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-07-08T10:58:05Z","updated_at":"2015-07-08T10:58:05Z","closed_at":null,"body":"Build a heap index so that for each object we know which other objects point to it. This allows a very efficient implementation of ```!gcroot```, and also something like SOSEX's ```!refs``` command that displays all references to and from an object. It also has potential to help with other heap walking algorithms.\r\n\r\nWe can't afford the memory to build a full index, so we need a card table instead. For each range of (say) 1KB objects, store the indices of the 1KB ranges that point to that range. This makes lookup slower by a constant factor, but decreases memory usage considerably for large heaps."}}