fabianishere / hugetable Goto Github PK

Use gRPC for defining the services.

This issue is concerned with implementing group membership: keeping track of the active members in the HugeTable fleet and having the master reap group members that have lost connection.

Starting point: https://github.com/apache/curator/blob/master/curator-recipes/src/main/java/org/apache/curator/framework/recipes/nodes/GroupMember.java

Relevant literature:

Bigtable uses Chubby to keep track of tablet servers. When a tablet server starts, it creates, and acquires an exclusive lock on, a uniquely-named file in a specific Chubby directory. The master monitors this directory (the servers directory) to discover tablet servers. A tablet server stops serving its tablets if it loses its exclusive lock: e.g., due to a network partition that caused the server to lose its Chubby session. (Chubby provides an efficient mechanism that allows a tablet server to check whether it still holds its lock without incurring network traffic.)
The master is responsible for detecting when a tablet server is no longer serving its tablets, and for reassign- ing those tablets as soon as possible. To detect when a tablet server is no longer serving its tablets, the master periodically asks each tablet server for the status of its lock. If a tablet server reports that it has lost its lock, or if the master was unable to reach a server during its last several attempts, the master attempts to acquire an exclusive lock on the server’s file. If the master is able to acquire the lock, then Chubby is live and the tablet server is either dead or having trouble reaching Chubby, so the master ensures that the tablet server can never serve again by deleting its server file. Once a server’s file has been deleted, the master can move all the tablets that were previously assigned to that server into the set of unassigned tablets