Hi,
In reply to Dikang Gu:
For the run where we incorporated the change from CASSANDRA-11571 the
stack trace was like this (from JMC):
*Stack Trace* *Sample Count* *Percentage(%)*
org.apache.cassandra.db.compaction.LeveledCompactionStrategy.getNextBackgroundTask(int)
229 11.983
-org.apach
On Sat, Nov 26, 2016 at 6:30 PM, Dikang Gu wrote:
> Hi Marcus,
>
> Do you have some stack trace to show that which function in the `
> getNextBackgroundTask` is most expensive?
>
> Yeah, I think having 15-20K sstables in L0 is very bad, in our heavy-write
> cluster, I try my best to reduce the imp
Hi Marcus,
Do you have some stack trace to show that which function in the `
getNextBackgroundTask` is most expensive?
Yeah, I think having 15-20K sstables in L0 is very bad, in our heavy-write
cluster, I try my best to reduce the impact of repair, and keep number of
sstables in L0 < 100.
Thanks
> The reason is described here:
https://issues.apache.org/jira/browse/CASSANDRA-5371?focusedCommentId=13621679&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13621679
>
> /Marcus
"...a lot of the work you've done you will redo when you compact your now
bigger L0 ssta
me, though –
> Carl / Marcus, any insight into why it’s within the loop instead of before
> it?
>
>
>
>
>
> *From: *Marcus Olsson
> *Organization: *Ericsson AB
> *Reply-To: *"dev@cassandra.apache.org"
> *Date: *Wednesday, November 23, 2016 at 7:52 AM
>
into why it’s
within the loop instead of before it?
From: Marcus Olsson
Organization: Ericsson AB
Reply-To: "dev@cassandra.apache.org"
Date: Wednesday, November 23, 2016 at 7:52 AM
To: "dev@cassandra.apache.org"
Subject: STCS in L0 behaviour
Hi everyone,
Without yet reading the code, what you describe sounds like a reasonable
optimization / fix, suitable for 3.0+ (probably not 2.2, definitely not 2.1)
--
Jeff Jirsa
> On Nov 23, 2016, at 7:52 AM, Marcus Olsson wrote:
>
> Hi everyone,
>
> TL;DR
> Should LCS be changed to always prefer an STCS
Hi everyone,
TL;DR
Should LCS be changed to always prefer an STCS compaction in L0 if it's
falling behind? Assuming that STCS in L0 is enabled.
Currently LCS seems to check if there is a possible L0->L1 compaction
before checking if it's falling behind, which in our case used between
15-30% of
