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https://issues.apache.org/jira/browse/CASSANDRA-8457?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15863758#comment-15863758
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Jason Brown commented on CASSANDRA-8457:
----------------------------------------
OK, so I've been performance load testing the snot of this code for the last
several weeks, with help from netty committers, flight recorder, and flame
graphs. As a result, I've made some major and some minor tweaks, and now I'm
slightly faster than trunk with slightly better throughput. I have some
optimizations in my back pocket that will increase even more, but as Sylvain
has stated before, we'll save those for follow up tickets.
trunk
{code}
id, type total ops, op/s, pk/s, row/s, mean,
med, .95, .99, .999, max, time, stderr, errors, gc: #, max
ms, sum ms, sdv ms, mb
4 threadCount, total, 233344, 3889, 3889, 3889, 1.0,
1.0, 1.2, 1.3, 1.5, 68.2, 60.0, 0.01549, 0, 9,
538, 538, 4, 5381
8 threadCount, total, 544637, 9076, 9076, 9076, 0.8,
0.8, 1.0, 1.1, 1.4, 73.8, 60.0, 0.00978, 0, 20,
1267, 1267, 5, 11848
16 threadCount, total, 1126627, 18774, 18774, 18774, 0.8,
0.8, 0.9, 1.0, 5.5, 78.2, 60.0, 0.01882, 0, 40,
2665, 2665, 6, 23666
24 threadCount, total, 1562460, 26036, 26036, 26036, 0.9,
0.8, 1.0, 1.1, 9.1, 81.3, 60.0, 0.00837, 0, 55,
3543, 3543, 9, 32619
36 threadCount, total, 2098097, 34962, 34962, 34962, 1.0,
0.9, 1.1, 1.3, 60.9, 83.0, 60.0, 0.00793, 0, 73,
4665, 4665, 7, 43144
54 threadCount, total, 2741814, 45686, 45686, 45686, 1.1,
1.0, 1.4, 1.7, 62.2, 131.7, 60.0, 0.01321, 0, 93,
5748, 5748, 7, 55097
81 threadCount, total, 3851131, 64166, 64166, 64166, 1.2,
1.0, 1.6, 2.6, 62.3, 151.7, 60.0, 0.01152, 0, 159,
8190, 8521, 14, 106805
121 threadCount, total, 4798169, 79947, 79947, 79947, 1.5,
1.1, 2.0, 3.0, 63.5, 117.8, 60.0, 0.05689, 0, 165,
9323, 9439, 5, 97536
181 threadCount, total, 5647043, 94088, 94088, 94088, 1.9,
1.4, 2.6, 4.9, 68.5, 169.2, 60.0, 0.01639, 0, 195,
10106, 11011, 11, 126422
271 threadCount, total, 6450510, 107461, 107461, 107461, 2.5,
1.8, 3.7, 12.0, 75.4, 155.8, 60.0, 0.01542, 0, 228,
10304, 12789, 9, 143857
406 threadCount, total, 6700764, 111635, 111635, 111635, 3.6,
2.5, 5.3, 55.8, 75.6, 196.5, 60.0, 0.01800, 0, 243,
9995, 13170, 7, 144166
609 threadCount, total, 7119535, 118477, 118477, 118477, 5.1,
3.5, 7.9, 62.8, 85.1, 170.0, 60.1, 0.01775, 0, 250,
10149, 13781, 7, 148118
913 threadCount, total, 7093347, 117981, 117981, 117981, 7.7,
4.9, 15.7, 71.3, 101.1, 173.4, 60.1, 0.02780, 0, 246,
10327, 13859, 8, 155896
{code}
8457
{code}
id, type total ops, op/s, pk/s, row/s, mean,
med, .95, .99, .999, max, time, stderr, errors, gc: #, max
ms, sum ms, sdv ms, mb
4 threadCount, total, 161668, 2694, 2694, 2694, 1.4,
1.4, 1.6, 1.7, 3.2, 68.2, 60.0, 0.01264, 0, 6,
363, 363, 4, 3631
8 threadCount, total, 498139, 8301, 8301, 8301, 0.9,
0.9, 1.1, 1.3, 1.8, 73.5, 60.0, 0.00446, 0, 19,
1164, 1164, 6, 11266
16 threadCount, total, 765437, 12756, 12756, 12756, 1.2,
1.2, 1.4, 1.5, 5.7, 74.8, 60.0, 0.01251, 0, 29,
1819, 1819, 5, 17238
24 threadCount, total, 1122768, 18710, 18710, 18710, 1.2,
1.2, 1.4, 1.5, 8.5, 127.7, 60.0, 0.00871, 0, 42,
2538, 2538, 5, 25054
36 threadCount, total, 1649658, 27489, 27489, 27489, 1.3,
1.2, 1.4, 1.6, 60.1, 77.7, 60.0, 0.00627, 0, 57,
3652, 3652, 7, 33743
54 threadCount, total, 2258999, 37641, 37641, 37641, 1.4,
1.3, 1.6, 1.8, 62.5, 81.7, 60.0, 0.00771, 0, 79,
4908, 4908, 6, 46789
81 threadCount, total, 3255005, 54220, 54220, 54220, 1.5,
1.2, 1.7, 2.2, 63.8, 133.4, 60.0, 0.02030, 0, 117,
6953, 7008, 9, 72208
121 threadCount, total, 4643184, 77293, 77293, 77293, 1.5,
1.2, 1.8, 2.9, 62.6, 112.7, 60.1, 0.02449, 0, 171,
8976, 9135, 9, 101583
181 threadCount, total, 5625693, 93731, 93731, 93731, 1.9,
1.4, 2.4, 4.8, 67.2, 208.1, 60.0, 0.02373, 0, 217,
9675, 11585, 11, 138725
271 threadCount, total, 6213997, 103523, 103523, 103523, 2.6,
1.8, 3.5, 27.2, 69.7, 183.1, 60.0, 0.01456, 0, 227,
9977, 12392, 7, 137334
406 threadCount, total, 6832341, 113808, 113808, 113808, 3.5,
2.4, 5.1, 57.4, 73.2, 179.0, 60.0, 0.01437, 0, 242,
10100, 13373, 8, 146086
609 threadCount, total, 7272610, 121130, 121130, 121130, 5.0,
3.4, 7.7, 62.8, 78.3, 134.9, 60.0, 0.02995, 0, 254,
10177, 14088, 8, 152827
913 threadCount, total, 7437538, 123715, 123715, 123715, 7.3,
4.7, 15.0, 69.9, 86.1, 252.8, 60.1, 0.01407, 0, 264,
10316, 14669, 11, 164130
{code}
Also, [~aweisberg] has been reviewing on the side and has made some nice
comments, as well.
Overview of changes:
- less reliance on pipeline
I've reduced the number of handlers in the netty pipeline to a bare minimum
(that is, just one) as I've found in my testing that there is a slight cost to
operating the netty pipeline: each handler look up the next handler, checking
the promise's status, and so on. While this change makes the code less like a
pipeline/chain of commands, it is still easily understandable and will perform
better. (As an aside, I have a colleague who runs a massively scalable service,
and they don't use any handlers in the netty pipeline whatsoever - they just
send ByteBufs to the channel.)
- fixing flush strategy
I've had to dive into the internals of netty to understand all the subtleties
of how flushing and thread scheduling works, and then matrix that against our
needs. Thus, I've documented it quite thoroughly in the class-level
documentation in {{OutboundMessageConnection}} and {{MessageOutHandler}}, and
the code implements those details.
> nio MessagingService
> --------------------
>
> Key: CASSANDRA-8457
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8457
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Jonathan Ellis
> Assignee: Jason Brown
> Priority: Minor
> Labels: netty, performance
> Fix For: 4.x
>
>
> Thread-per-peer (actually two each incoming and outbound) is a big
> contributor to context switching, especially for larger clusters. Let's look
> at switching to nio, possibly via Netty.
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