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https://issues.apache.org/jira/browse/CASSANDRA-2893?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13174558#comment-13174558
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Brandon Williams commented on CASSANDRA-2893:
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Maybe a chart isn't the best way to look at this. First, let me note that I
mislabeled the X axis, this is _micro_seconds since I measured from
cfhistograms to avoid any network interference, so the differences are smaller
than I originally implied (and may explain the throughput similarity since
network latency would dominate.)
Let's look at this statistically (as derived from the histogram data) instead.
h4. Non-contended
||type||trunk||2893||
|Mean|9.0105|9.0113|
|SD|7.5795|7.6782|
|10th %|5|5|
|25th %|6|7|
|50th %|8|8|
|75th %|10|10|
|95th %|42|42|
|99th %|103|103|
h4. Contended
||type||trunk||2893||
|Mean|10.2212|10.2820|
|SD|8.1631|12.6250|
|10th %|6|8|
|25th %|7|10|
|50th %|8|12|
|75th %|12|17|
|95th %|42|72|
|99th %|103|124|
Non-contended is almost exactly the same in every way. Things begin to differ
with a contended row, but nothing I would call twice as bad.
> Add row-level isolation
> -----------------------
>
> Key: CASSANDRA-2893
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2893
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Jonathan Ellis
> Assignee: Sylvain Lebresne
> Priority: Minor
> Fix For: 1.1
>
> Attachments: 0001-Move-deletion-infos-into-ISortedColumns-v2.patch,
> 0001-Move-deletion-infos-into-ISortedColumns.patch,
> 0002-Make-memtable-use-CF.addAll-v2.patch,
> 0002-Make-memtable-use-CF.addAll.patch,
> 0003-Add-AtomicSortedColumn-and-snapTree-v2.patch,
> 0003-Add-AtomicSortedColumn-and-snapTree.patch, latency-plain.svg,
> latency.svg, snaptree-0.1-SNAPSHOT.jar
>
>
> This could be done using an the atomic ConcurrentMap operations from the
> Memtable and something like http://code.google.com/p/pcollections/ to replace
> the ConcurrentSkipListMap in ThreadSafeSortedColumns. The trick is that
> pcollections does not provide a SortedMap, so we probably need to write our
> own.
> Googling [persistent sortedmap] I found
> http://code.google.com/p/actord/source/browse/trunk/actord/src/main/scala/ff/collection
> (in scala) and http://clojure.org/data_structures#Data Structures-Maps.
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