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https://issues.apache.org/jira/browse/CASSANDRA-19429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17828541#comment-17828541
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Dipietro Salvatore commented on CASSANDRA-19429:
------------------------------------------------
[~rustyrazorblade] Can you provide more info on how you have test it? What
commands did you run to load the DB and benchmark it? What throughput did you
register?
I have tried to reproduce it following your settings but I was not able to see
the same results and, in my case, I still see 1.5x improvement on c5.18xl with
the [~smiklosovic] patch. I have also tried to test it without all the OS and
Cassandra optimizations you provided, and the results are similar. Full
commands list used below:
{code:java}
# From fresh AWS Ubuntu 22.04 instance
# Basic upgrade of packages and install few tools
sudo apt update && sudo apt upgrade -y
sudo apt install -y unzip tmux
## JAVA 11 OpenJDKs
sudo apt install -y openjdk-11-jdk ant
java --version
# Download Cassandra
cd
wget https://github.com/apache/cassandra/archive/refs/tags/cassandra-4.1.3.zip
&& unzip cassandra-4.1.3.zip && cd ~/cassandra-cassandra-4.1.3/
# Patched
# git clone https://github.com/instaclustr/cassandra.git cassandra-instaclustr
&& cd cassandra-instaclustr && git checkout CASSANDRA-19429-4.1 && git log -10
--oneline
# Start DB
CASSANDRA_USE_JDK11=true ant realclean && \
CASSANDRA_USE_JDK11=true ant jar && \
CASSANDRA_USE_JDK11=true ant stress-build && \
rm -rf data && \
bin/cassandra -f -R
# Start workload
bin/cqlsh -e 'drop table if exists keyspace1.standard1;' && \
bin/cqlsh -e 'drop keyspace if exists keyspace1;' && \
bin/nodetool clearsnapshot --all && \
tools/bin/cassandra-stress write n=10000000 cl=ONE -rate threads=384 -node
127.0.0.1 -log file=cload.log -graph file=cload.html && \
bin/nodetool compact keyspace1 && \
sleep 30s && \
tools/bin/cassandra-stress mixed ratio\(write=10,read=90\) duration=10m cl=ONE
-rate threads=100 -node localhost -log file=result.log -graph file=graph.html
|& tee stress.txt
{code}
The difference in performance it is also clear on the graph.html report at the
end of the execution. After around 300sec into the benchmark, the CPU
utilization drops to 30% and so the performance while, with the patch, it
remains much more constant through the entire experiment with a avg cpu
utilization of 75% and 5x lower P99 latency.
!Screenshot 2024-03-19 at 15.22.50.png!
> Remove lock contention generated by getCapacity function in SSTableReader
> -------------------------------------------------------------------------
>
> Key: CASSANDRA-19429
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19429
> Project: Cassandra
> Issue Type: Bug
> Components: Local/SSTable
> Reporter: Dipietro Salvatore
> Assignee: Dipietro Salvatore
> Priority: Normal
> Fix For: 4.0.x, 4.1.x
>
> Attachments: Screenshot 2024-02-26 at 10.27.10.png, Screenshot
> 2024-02-27 at 11.29.41.png, Screenshot 2024-03-19 at 15.22.50.png,
> asprof_cass4.1.3__lock_20240216052912lock.html,
> image-2024-03-08-15-51-30-439.png, image-2024-03-08-15-52-07-902.png
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Profiling Cassandra 4.1.3 on large AWS instances, a high number of lock
> acquires is measured in the `getCapacity` function from
> `org/apache/cassandra/cache/InstrumentingCache` (1.9M lock acquires per 60
> seconds). Based on our tests on r8g.24xlarge instances (using Ubuntu 22.04),
> this limits the CPU utilization of the system to under 50% when testing at
> full load and therefore limits the achieved throughput.
> Removing the lock contention from the SSTableReader.java file by replacing
> the call to `getCapacity` with `size` achieves up to 2.95x increase in
> throughput on r8g.24xlarge and 2x on r7i.24xlarge:
> |Instance type|Cass 4.1.3|Cass 4.1.3 patched|
> |r8g.24xlarge|168k ops|496k ops (2.95x)|
> |r7i.24xlarge|153k ops|304k ops (1.98x)|
>
> Instructions to reproduce:
> {code:java}
> ## Requirements for Ubuntu 22.04
> sudo apt install -y ant git openjdk-11-jdk
> ## Build and run
> CASSANDRA_USE_JDK11=true ant realclean && CASSANDRA_USE_JDK11=true ant jar &&
> CASSANDRA_USE_JDK11=true ant stress-build && rm -rf data && bin/cassandra -f
> -R
> # Run
> bin/cqlsh -e 'drop table if exists keyspace1.standard1;' && \
> bin/cqlsh -e 'drop keyspace if exists keyspace1;' && \
> bin/nodetool clearsnapshot --all && tools/bin/cassandra-stress write
> n=10000000 cl=ONE -rate threads=384 -node 127.0.0.1 -log file=cload.log
> -graph file=cload.html && \
> bin/nodetool compact keyspace1 && sleep 30s && \
> tools/bin/cassandra-stress mixed ratio\(write=10,read=90\) duration=10m
> cl=ONE -rate threads=406 -node localhost -log file=result.log -graph
> file=graph.html
> {code}
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