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https://issues.apache.org/jira/browse/CASSANDRA-19429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17821436#comment-17821436
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Dipietro Salvatore commented on CASSANDRA-19429:
------------------------------------------------
Test without compaction after writes and with nodetool disableautocompaction
and just READs
Cmd:
{code:java}
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
disableautocompaction && sleep 30s && tools/bin/cassandra-stress mixed
ratio\(write=0,read=100\) duration=10m cl=ONE -rate threads=100 -node localhost
-log file=result.log -graph file=graph.html {code}
Results using Ubuntu22.04 on r8g.24xlarge with stress test colocated on the
same instance :
* 4.1.3 released:
{code:java}
Results:
Op rate : 637,636 op/s [READ: 637,636 op/s]
Partition rate : 637,636 pk/s [READ: 637,636 pk/s]
Row rate : 637,636 row/s [READ: 637,636 row/s]
Latency mean : 0.1 ms [READ: 0.1 ms]
Latency median : 0.1 ms [READ: 0.1 ms]
Latency 95th percentile : 0.2 ms [READ: 0.2 ms]
Latency 99th percentile : 0.2 ms [READ: 0.2 ms]
Latency 99.9th percentile : 2.6 ms [READ: 2.6 ms]
Latency max : 21.8 ms [READ: 21.8 ms]
Total partitions : 382,809,565 [READ: 382,809,565]
Total errors : 0 [READ: 0]
Total GC count : 3,379
Total GC memory : 5406.356 GiB
Total GC time : 5.5 seconds
Avg GC time : 1.6 ms
StdDev GC time : 0.8 ms
Total operation time : 00:10:00 {code}
* 4.1.3 with patch:
{code:java}
Results:
Op rate : 636,043 op/s [READ: 636,043 op/s]
Partition rate : 636,043 pk/s [READ: 636,043 pk/s]
Row rate : 636,043 row/s [READ: 636,043 row/s]
Latency mean : 0.1 ms [READ: 0.1 ms]
Latency median : 0.1 ms [READ: 0.1 ms]
Latency 95th percentile : 0.2 ms [READ: 0.2 ms]
Latency 99th percentile : 0.2 ms [READ: 0.2 ms]
Latency 99.9th percentile : 2.7 ms [READ: 2.7 ms]
Latency max : 16.2 ms [READ: 16.2 msz]
Total partitions : 381,776,733 [READ: 381,776,733]
Total errors : 0 [READ: 0]
Total GC count : 3,396
Total GC memory : 5433.623 GiB
Total GC time : 5.6 seconds
Avg GC time : 1.6 ms
StdDev GC time : 0.5 ms
Total operation time : 00:10:00 {code}
The patch doesn't have any effect on the read only workload
> 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, asprof_cass4.1.3__lock_20240216052912lock.html
>
> 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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