Handoffs are too slow after netsplit

Douglas Rohrer drohrer at basho.com
Thu Feb 23 07:14:50 EST 2017


Andrey:

It's waiting for 60 seconds, literally...

See
https://github.com/basho/riak_core/search?utf8=%E2%9C%93&q=vnode_inactivity_timeout
-
handoff is not initiated until a vnode has been inactive for the specified
inactivity period.

For demonstration purposes, if you want to reduce this time, you could set
the riak_core.vnode_inactivity_timeout period lower ,which can be set in
advanced.config. Also note that, depending on the backend you use, it's
possible to have other settings set lower than the vnode inactivity
timeout, you can actually prevent handoff completely - see
http://docs.basho.com/riak/kv/2.2.0/setup/planning/backend/bitcask/#sync-strategy,
for examnple.

Hope this helps.

Doug

On Thu, Feb 23, 2017 at 6:40 AM Andrey Ershov <andrershov at gmail.com> wrote:

Hi, guys!

I'd like to follow up on handoffs behaviour after netsplit. The problem is
that right after network partition is healed, "riak-admin transfers"
command says that there are X partitions waiting transfer from one node to
another, and Y partitions waiting transfer in the opposite direction. What
are they waiting for? Active transfers section is always empty. It takes
about 1 minute for transfer to occur. I've increased transfer_limit to 100
and it does not help.
Also I've tried to attach to Erlang VM and execute
riak_core_vnode_manager:force_handoff() on each node. This command returns
'ok'. But seems that it does not work right after network is healed. After
some time 30-60 s, force_handoff() works as expected, but actually it's the
same latency as in auto handoff case.

So what is it waiting for? Any ideas?

I'm preparing real-time coding demo to be shown on the conference. So it's
too much time to wait for 1 minute for handoff to occur just for a couple
of keys...
-- 
Thanks,
Andrey
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