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https://issues.apache.org/jira/browse/CASSANDRA-20250?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17924714#comment-17924714
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Dmitry Konstantinov edited comment on CASSANDRA-20250 at 2/6/25 10:48 PM:
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I have added a very basic JMH to compare increment throughput -
[code|https://github.com/apache/cassandra/compare/trunk...netudima:cassandra:20250_proto-trunk]
This is the result of execution on my laptop (MacOS, OpenJDK11, 2,6 GHz 6-Core
Intel Core i7), ideally I need to run it on a server machine for more relevant
results:
{code:java}
[java] Benchmark (type) Mode Cnt
Score Error Units
[java] ThreadLocalMetricsBench.increment LongAdder thrpt 16
528024.232 ± 5197.699 ops/ms
[java] ThreadLocalMetricsBench.increment LazySetArray thrpt 16
957165.739 ± 7878.474 ops/ms
[java] ThreadLocalMetricsBench.increment PiggybackArray thrpt 16
1016821.284 ± 24017.736 ops/ms
{code}
[^async_profiler_cpu_profiles.zip]
[^jmh-result.json]
The next steps I think is to add delta and delta + Int2IntHashMap
implementations..
was (Author: dnk):
I have added a very basic JMH to compare increment throughput -
[code|https://github.com/apache/cassandra/compare/trunk...netudima:cassandra:20250_proto-trunk]
This is the result from my laptop (MacOS, OpenJDK11, 2,6 GHz 6-Core Intel Core
i7), I need to run it on a server machine for more relevant results:
{code:java}
[java] Benchmark (type) Mode Cnt
Score Error Units
[java] ThreadLocalMetricsBench.increment LongAdder thrpt 16
528024.232 ± 5197.699 ops/ms
[java] ThreadLocalMetricsBench.increment LazySetArray thrpt 16
957165.739 ± 7878.474 ops/ms
[java] ThreadLocalMetricsBench.increment PiggybackArray thrpt 16
1016821.284 ± 24017.736 ops/ms
{code}
[^async_profiler_cpu_profiles.zip]
[^jmh-result.json]
the next steps I think to add delta and delta + Int2IntHashMap implementations..
> Provide the ability to disable specific metrics collection
> ----------------------------------------------------------
>
> Key: CASSANDRA-20250
> URL: https://issues.apache.org/jira/browse/CASSANDRA-20250
> Project: Apache Cassandra
> Issue Type: New Feature
> Components: Observability/Metrics
> Reporter: Dmitry Konstantinov
> Priority: Normal
> Attachments: async_profiler_cpu_profiles.zip,
> cpu_profile_insert.html, jmh-result.json
>
>
> Cassandra has a lot of metrics collected, many of them are collected per
> table, so their instance number is multiplied by number of tables. From one
> side it gives a better observability, from another side metrics are not for
> free, there is an overhead associated with them:
> 1) CPU overhead: in case of simple CPU bound load: I already see like 5.5% of
> total CPU spent for metrics in cpu framegraphs for read load and 11% for
> write load.
> Example: [^cpu_profile_insert.html] (search by "codahale" pattern)
> 2) memory overhead: we spend memory for entities used to aggregate metrics
> such as LongAdders and reservoirs + for MBeans (String concatenation within
> object names is a major cause of it, for each table+metric name combination a
> new String is created)
>
> The idea of this ticket is to allow an operator to configure a list of
> disabled metrics in cassandra.yaml, like:
> {code:java}
> disabled_metrics:
> - metric_a
> - metric_b
> {code}
> From implementation point of view I see two possible approaches (which can be
> combined):
> # Generic: when a metric is registering if it is listed in disabled_metrics
> we do not publish it via JMX and provide a noop implementation of metric
> object (such as histogram) for it.
> Logging analogy: log level check within log method
> # Specialized: for some metrics the process of value calculation is not for
> free and introduces an overhead as well, in such cases it would be useful to
> check within specific logic using an API (like: isMetricEnabled) do we need
> to do it. Example of such metric:
> ClientRequestSizeMetrics.recordRowAndColumnCountMetrics
> Logging analogy: an explicit 'if (isDebugEnabled())' condition used when a
> message parameter is expensive.
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