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From "Josh Elser (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-4328) Run multiple tablet servers on a single host
Date Mon, 06 Jun 2016 14:56:21 GMT


Josh Elser commented on ACCUMULO-4328:

The big question that I have is, even if you could do this, would you want to? Are there any
performance improvements running multiple tservers vs increasing thread counts and memory
on a single tserver? I don't think we are normally CPU bound, and multiple tservers are going
to be contending for the same IO bandwidth. If we had a benchmark where this did show substantial
improvement, then maybe its okay for the 1.6 line. If we don't have that or the time to evaluate
it, then 1.7+ may be a better option so that we don't get into a case where - sure its possible
- but don't ever do that because A, B ... Z in 1.6.6, use 1.7.x where we fixed that...

I think [~afuchs] did some sort of benchmark a while back which showed some promise, but that
was, IIRC, related to contention in rolling WALs -- something that [~ecn] made better with
ACCUMULO-3423 in 1.8. Good benchmarks to understand the cases when this would have performance
benefits would be great documentation to include.

bq. I agree that random ports may be an issue, but its an issue that predates this JIRA.

Yes and no, IMO. This is formalizing the ability to run multiple TServers as a "feature" which
means it needs to be figured out.

bq. Would re-basing this PR against 1.7 be a sufficient compromise?

I'm a little less worried against 1.7, but am still not be in favor of it. I'd like to hear
what others have to say before I blindly -1 it. The only difference with my complaints with
it landing in 1.7 instead of 1.6 is that we have 4 fewer point-releases on 1.7 than 1.6, but
that's still two releases which would have different semantics. [~kturner], [~busbey], you
both often have good strong opinions on compatibility -- a bit of your time to provide some
opinions would be appreciated.

> Run multiple tablet servers on a single host
> --------------------------------------------
>                 Key: ACCUMULO-4328
>                 URL:
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: scripts, tserver
>            Reporter: Dave Marion
>            Assignee: Dave Marion
>          Time Spent: 10m
>  Remaining Estimate: 0h
> Modify scripts and necessary code to run multiple tablet servers on a single host.

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