-Re: Regarding QoS for Handlers
Stack 2013-10-14, 17:06
On Sun, Oct 13, 2013 at 1:36 PM, Varun Sharma <[EMAIL PROTECTED]> wrote:
> I am wondering if QoS on handler threads is being looked at by someone ?
What Devaraj said plus, trunk has HBASE-8884 "Pluggable RpcScheduler"
committed w/ two implementations currently -- our current coarse QoS that
works off method annotations and target region name and a new FIFO schedule
for the master RPCs. The authors, like yourselves, were motivated by
desire for a treatment that was other than our default prioritization
wanting to demark on whether the incoming RPC was a read or a write
(Beware, backport would be messy -- there was a few follow-on patches after
the initial commit).
> The issue with this could be that what happens when the user ends up
> directing most of their load to the high priority pool which has fewer
> threads. We could do something simple like having a tight upper bound on
> the call queue length and if a new high priority call is rejected from this
> pool, just enqueue it to the regular pool of requests.
> Thoughts ?
All sounds good to me Varun.
+ At a minimum we need a means of second-classing mapreduce workload.
+ Naive is fine. Beyond this, the problem gets complicated fast (LarsG and
AndrewWang talk at HBaseCon)
+ We just added 'priority' to the RPC header so client can say what
priority they want (Server can do what it likes with it).