| title | expires_at | tags | ||
|---|---|---|---|---|
Understanding Locks and Presences |
never |
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There are to types of entities that are managed by Locket:
-
Locks - only one lock can be acquired by the lock name at a time. The component that is holding the lock is considered an active component. Then it starts it tries to acquire the lock before serving any request or performing periodic operations. The following components are using Locket to acquire the lock in order to pick an active component:
- BBS (retry interval: 5s, ttl: 15s)
- Auctioneer (retry interval: 5s, ttl: 15s)
-
Presences - updated periodically to register component as active and being able to serve requests. Each Diego rep component is updating its presence with Locket. Retry interval: 5s TTL: 15s. Auctioneer will use the information provided by presences (by querying the database) to determine which Rep components are available to run the LRP/Task. When Rep does not update, it looses its presence and its LRPs are marked as suspect by BBS and they will start to be rescheduled to run on active Reps. If the Rep becomes active again all suspect LRPs will become active again and rescheduled LRPs will be deleted.