Now for a storm cluster with 40 hosts [with 32 cores/128G memory] and hundreds of topologies, nimbus submission and killing will take about minutes to finish. For example, for a cluster with 300 hundred of topologies，it will take about 8 minutes to submit a topology, this affect our efficiency seriously.
So, i check out the nimbus code and find two factor that will effect nimbus submission/killing time for a scheduling round:
- read existing-assignments from zookeeper for every topology [will take about 4 seconds for a 300 topologies cluster]
- read all the workers heartbeats and update the state to nimbus cache [will take about 30 seconds for a 300 topologies cluster]
the key here is that Storm now use zookeeper to collect heartbeats [not RPC], and also keep physical plan [assignments] using zookeeper which can be totally local in nimbus.
So, i think we should make some changes to storm's heartbeats and assignments management.
For assignment promotion:
1. nimbus will put the assignments in local disk
2. when restart or HA leader trigger nimbus will recover assignments from zk to local disk
3. nimbus will tell supervisor its assignment every time through RPC every scheduling round
4. supervisor will sync assignments at fixed time
For heartbeats promotion:
1. workers will report executors ok or wrong to supervisor at fixed time
2. supervisor will report workers heartbeats to nimbus at fixed time
3. if supervisor die, it will tell nimbus through runtime hook
or let nimbus find it through aware supervisor if is survive
4. let supervisor decide if worker is running ok or invalid , supervisor will tell nimbus which executors of every topology are ok