Srikanth Kandula created YARN-4088:
Summary: RM should be able to process heartbeats from NM
Project: Hadoop YARN
Issue Type: Improvement
Components: resourcemanager, scheduler
Reporter: Srikanth Kandula
Today, the RM sequentially processes one heartbeat after another.
Imagine a 3000 server cluster with each server heart-beating every 3s. This
gives the RM 1ms on average to process each NM heartbeat. That is tough.
It is true that there are several underlying datastructures that will be
touched during heartbeat processing. So, it is non-trivial to parallelize the
NM heartbeat. Yet, it is quite doable...
Parallelizing the NM heartbeat would substantially improve the scalability of
the RM, allowing it to either
a) run larger clusters or
b) support faster heartbeats or dynamic scaling of heartbeats
c) take more asks from each application or
c) use cleverer/ more expensive algorithms such as node labels or better
packing or ...
Indeed the RM's scalability limit has been cited as the motivating reason for a
variety of efforts which will become less needed if this can be solved. Ditto
for slow heartbeats. See Sparrow and Mercury papers for example.
Can we take a shot at this?
If not, could we discuss why.
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