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List:       cassandra-commits
Subject:    [jira] [Commented] (CASSANDRA-18766) high speculative retries on v4.1.3
From:       "Stefan Miklosovic (Jira)" <jira () apache ! org>
Date:       2024-03-30 11:47:00
Message-ID: JIRA.13547569.1692194914000.100226.1711799220030 () Atlassian ! JIRA
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Stefan Miklosovic commented on CASSANDRA-18766:
-----------------------------------------------

[~ivnovi] [~nicolas.henneaux] this one is interesting CASSANDRA-18766 It is there \
from times of 4.1-alpha1 ... What that patch seems to solve is that previously it was \
sending speculative retries but it should not. But if that ticket introduced the \
performance regression you see, then it might be actually other way around?

Another possibility is that the patch indeed fixes the discrepancy around units and \
it started to speculate just right and you see this in your tests as it was not \
speculating before but it should. 

[~jonmeredith] what do you think?

> high speculative retries on v4.1.3
> ----------------------------------
> 
> Key: CASSANDRA-18766
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18766
> Project: Cassandra
> Issue Type: Bug
> Components: Consistency/Coordination
> Reporter: Ivans Novikovs
> Priority: Normal
> Fix For: 4.1.x
> 
> Attachments: signature.asc
> 
> 
> There are up to 10+ times higher speculative retries for reads on 4.1.3 comparing \
> to 4.0.7 and 4.1.2 when using QUORUM and default setting of 99p. On 4.1.3 after \
> upgrade I see speculative retries for up to 35% of all reads for specific table. \
> Latency for reads is stable around 500 microseconds. java 1.8.0_382 is used



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