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https://issues.apache.org/jira/browse/CASSANDRA-15350?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16971341#comment-16971341
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Yifan Cai edited comment on CASSANDRA-15350 at 11/11/19 6:56 AM:
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The change of calculating the exact size of UTF-8 string has negative
performance impact. It needs to iterate through the entire string to determine
the actual size in UTF-8.
The [benchmark
setup|https://issues.apache.org/jira/secure/attachment/12985494/Utf8StringEncodeBench.java]
and the result:
{code:java}
[java] Benchmark Mode Cnt
Score Error Units
[java] Utf8StringEncodeBench.writeLongText avgt 6
552.458 ± 9.141 ns/op
[java] Utf8StringEncodeBench.writeLongTextWithExactSize avgt 6
787.676 ± 120.057 ns/op
[java] Utf8StringEncodeBench.writeShortText avgt 6
70.311 ± 8.031 ns/op
[java] Utf8StringEncodeBench.writeShortTextWithExactSize avgt 6
71.716 ± 4.790 ns/op
{code}
I will revert the change.
was (Author: yifanc):
The change of calculating the exact size of UTF-8 string has negative
performance impact. It needs to iterate through the entire string to determine
the actual size in UTF-8.
The benchmark setup and the result:
{code:java}
[java] Benchmark Mode Cnt
Score Error Units
[java] Utf8StringEncodeBench.writeLongText avgt 6
552.458 ± 9.141 ns/op
[java] Utf8StringEncodeBench.writeLongTextWithExactSize avgt 6
787.676 ± 120.057 ns/op
[java] Utf8StringEncodeBench.writeShortText avgt 6
70.311 ± 8.031 ns/op
[java] Utf8StringEncodeBench.writeShortTextWithExactSize avgt 6
71.716 ± 4.790 ns/op
{code}
I will revert the change.
> Add CAS “uncertainty” and “contention" messages that are currently propagated
> as a WriteTimeoutException.
> ---------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-15350
> URL: https://issues.apache.org/jira/browse/CASSANDRA-15350
> Project: Cassandra
> Issue Type: Improvement
> Components: Feature/Lightweight Transactions
> Reporter: Alex Petrov
> Assignee: Yifan Cai
> Priority: Normal
> Labels: protocolv5, pull-request-available
> Attachments: Utf8StringEncodeBench.java
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Right now, CAS uncertainty introduced in
> https://issues.apache.org/jira/browse/CASSANDRA-6013 is propagating as
> WriteTimeout. One of this conditions it manifests is when there’s at least
> one acceptor that has accepted the value, which means that this value _may_
> still get accepted during the later round, despite the proposer failure.
> Similar problem happens with CAS contention, which is also indistinguishable
> from the “regular” timeout, even though it is visible in metrics correctly.
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