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https://issues.apache.org/jira/browse/CASSANDRA-19429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17821383#comment-17821383
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Dipietro Salvatore commented on CASSANDRA-19429:
------------------------------------------------
1. Test without compaction after writes.
Cmd used:
{code:java}
sbin/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 && 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
{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 : 167,478 op/s [READ: 150,727 op/s, WRITE: 16,750
op/s]
Partition rate : 167,478 pk/s [READ: 150,727 pk/s, WRITE: 16,750
pk/s]
Row rate : 167,478 row/s [READ: 150,727 row/s, WRITE: 16,750
row/s]
Latency mean : 0.6 ms [READ: 0.6 ms, WRITE: 0.2 ms]
Latency median : 0.4 ms [READ: 0.5 ms, WRITE: 0.1 ms]
Latency 95th percentile : 1.6 ms [READ: 1.6 ms, WRITE: 0.2 ms]
Latency 99th percentile : 2.2 ms [READ: 2.2 ms, WRITE: 0.3 ms]
Latency 99.9th percentile : 7.1 ms [READ: 7.3 ms, WRITE: 1.2 ms]
Latency max : 48.3 ms [READ: 48.3 ms, WRITE: 46.0 ms]
Total partitions : 100,600,039 [READ: 90,538,533, WRITE: 10,061,506]
Total errors : 0 [READ: 0, WRITE: 0]
Total GC count : 1,515
Total GC memory : 2411.407 GiB
Total GC time : 8.3 seconds
Avg GC time : 5.5 ms
StdDev GC time : 2.4 ms
Total operation time : 00:10:00{code}
- 4.1.3 with patch:
{code:java}
Results:
Op rate : 435,180 op/s [READ: 391,655 op/s, WRITE: 43,525
op/s]
Partition rate : 435,180 pk/s [READ: 391,655 pk/s, WRITE: 43,525
pk/s]
Row rate : 435,180 row/s [READ: 391,655 row/s, WRITE: 43,525
row/s]
Latency mean : 0.2 ms [READ: 0.2 ms, WRITE: 0.2 ms]
Latency median : 0.2 ms [READ: 0.2 ms, WRITE: 0.2 ms]
Latency 95th percentile : 0.3 ms [READ: 0.3 ms, WRITE: 0.2 ms]
Latency 99th percentile : 0.4 ms [READ: 0.4 ms, WRITE: 0.3 ms]
Latency 99.9th percentile : 6.7 ms [READ: 6.7 ms, WRITE: 6.2 ms]
Latency max : 1057.5 ms [READ: 1,057.5 ms, WRITE: 47.7 ms]
Total partitions : 261,410,615 [READ: 235,265,301, WRITE: 26,145,314]
Total errors : 0 [READ: 0, WRITE: 0]
Total GC count : 4,543
Total GC memory : 7225.988 GiB
Total GC time : 25.7 seconds
Avg GC time : 5.7 ms
StdDev GC time : 3.1 ms
Total operation time : 00:10:00{code}
Patch seems to have huge benefit on this case as well (2.6x).
Noticed also huge benefit in P99 latency (5.5x decrease).
> 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,
> 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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