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From "Gopal V (JIRA)" <>
Subject [jira] [Updated] (HIVE-10474) LLAP: investigate why TPCH Q1 1k is slow
Date Fri, 24 Apr 2015 15:34:39 GMT


Gopal V updated HIVE-10474:
    Attachment: llap-gc-pauses.png

I restored the HADOOP-11772 fix on the cluster and re-ran this.

The GC pressure has gone way up since I tested this last - 20-25 full collections every minute.


something's changed that made the tenured generation huge recently - the daemon slows down
as you keep using it. This looks like a recent regression in perf.

> LLAP: investigate why TPCH Q1 1k is slow
> ----------------------------------------
>                 Key: HIVE-10474
>                 URL:
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Sergey Shelukhin
>         Attachments: llap-gc-pauses.png
> While most queries run faster in LLAP than just Tez with container reuse, TPCH Q1 is
much slower.
> On my run, on tez with container reuse (current default LLAP configuration but mode ==
container and no daemons running)  runs 2-6 (out of 6 consecutive runs in the same session)
finished in 25.5sec average; with 16 LLAP daemons in default config the average was 35.5sec;
same w/o IO elevator (to rule out its impact) it took 59.7sec w/strange distribution (later
runs were slower than earlier runs, still, fastest run was 49.5sec).
> So excluding IO elevator it's more than 2x degradation.
> We need to figure out why this is happening. Is it just slot discrepancy? Regardless,
this needs to be addressed.

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