cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Christopher Smith (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6106) QueryState.getTimestamp() & FBUtilities.timestampMicros() reads current timestamp with System.currentTimeMillis() * 1000 instead of System.nanoTime() / 1000
Date Tue, 01 Apr 2014 13:40:19 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13956496#comment-13956496
] 

Christopher Smith commented on CASSANDRA-6106:
----------------------------------------------

So, looking at JNA, it seems like shared memory/NIO buffer logic could be done with it as
much as it could be done with JNI. Is it possible what I'm talking about could be done through
JNA as much as with JNI?

> QueryState.getTimestamp() & FBUtilities.timestampMicros() reads current timestamp
with System.currentTimeMillis() * 1000 instead of System.nanoTime() / 1000
> ------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6106
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6106
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>         Environment: DSE Cassandra 3.1, but also HEAD
>            Reporter: Christopher Smith
>            Assignee: Benedict
>            Priority: Minor
>              Labels: timestamps
>             Fix For: 2.1 beta2
>
>         Attachments: microtimstamp.patch, microtimstamp_random.patch, microtimstamp_random_rev2.patch
>
>
> I noticed this blog post: http://aphyr.com/posts/294-call-me-maybe-cassandra mentioned
issues with millisecond rounding in timestamps and was able to reproduce the issue. If I specify
a timestamp in a mutating query, I get microsecond precision, but if I don't, I get timestamps
rounded to the nearest millisecond, at least for my first query on a given connection, which
substantially increases the possibilities of collision.
> I believe I found the offending code, though I am by no means sure this is comprehensive.
I think we probably need a fairly comprehensive replacement of all uses of System.currentTimeMillis()
with System.nanoTime().



--
This message was sent by Atlassian JIRA
(v6.2#6252)

Mime
View raw message