Investigate mvn4 large graph performance regression

[mbien]

Affected version

4.0.0-rc-3 (resolver 2.0.9)

Bug description

I use this issue to investigate the performance regression posted on the dev list. Github allows to embed pictures which makes sharing flame graphs easier compared to mail.

benchmark project taken from mail thread (thanks to @seregamorph for coming up with a reproducer!):
https://github.com/maven-turbo-reactor/maven-multiproject-generator (https://www.mail-archive.com/dev@maven.apache.org/msg135612.html)

setup (first line are kernel settings for async-profiler):

sudo sysctl kernel.kptr_restrict=0 && sudo sysctl kernel.perf_event_paranoid=1
export JAVA_HOME=/home/mbien/dev/java/jdk-24.0.1.9.1-corretto

mvn3 run:

export MAVEN_OPTS=-agentpath:/home/mbien/dev/java/async-profiler-4.0-linux-x64/lib/libasyncProfiler.so=start,event=cpu,file=maven3.html
/home/mbien/dev/java/apache-maven-9.9.10_40/bin/mvn clean install

mvn4 run:

export MAVEN_OPTS=-agentpath:/home/mbien/dev/java/async-profiler-4.0-linux-x64/lib/libasyncProfiler.so=start,event=cpu,file=maven4.html
/home/mbien/dev/java/apache-maven-4.0.0-rc-3/bin/mvn clean install

(i ran a warmup run first before measuring)

m3
Total time:  01:03 min (Wall Clock)

m4
Total time:  03:08 min (Wall Clock)

(old intel i7 on NVME)

first observation:

mvn3 has 3 paths leading into DefaultRepositorySystem.collectDependencies, mvn4 has 4. The extra path comes from DefaultConsumerPomBuilder, see second observation.

Graphs show relative execution time. No totals.

Details

note: one path is very fast and not visible on this zoom level in both cases, purple marks collectDependencies

mvn3:

mvn4:

second observation:

The reason for that seems to be the install stage. More time is spent in InstallMojo:

Details

m3:

m4:

zooming in shows the difference, the whole RepositoryUtils.toArtifact path is new and is the cause for the extraDefaultRepositorySystem.collectDependencies call.

m3:

m4:

third observation:

more time is spent computing hash codes, purple highlights methods containing "hash".

Details

mvn3:

mvn4:

lets zoom into a single collectDependencies call

mvn3:

mvn4:

full flame graphs as html (compressed since github doesn't like html):

maven3.html.gz
maven4rc3.html.gz

[XenoAmess]

..my profiling show around 15% performance part is from getPluginsAsMap
will try refine it this weekend.

update: #2482

[XenoAmess]

1.2% + 0.7% be in the slow string format function. will refine it also.

update: #2483

[XenoAmess]

log flush: #2478

[XenoAmess]

delete several outdated classes(and their generated copies) #2484

[XenoAmess]

17.32% at the thread start in maven-resolver.
seems there be some thread management problems.
so yes I have to have a look at the maven-resolver repo also(never did this before)

update: apache/maven-resolver#1490
update: apache/maven-resolver#1492

[gnodet]

I think the current raised PRs solve most problems.
The remaining one is the resolver dependency tracker (bf consumes more resources than df but provides correct results).

[mbien]

@gnodet feel free to close whenever you see fit. I didn't have time to follow up on this unfortunately.

[gnodet]

@gnodet feel free to close whenever you see fit. I didn't have time to follow up on this unfortunately.

Yeah, I'll keep it opened until the PRs are merged:

• Improve Maven cache architecture for better memory efficiency and performance #2506
• Expand value interning optimization and fix XML factory transformer usage #2495
• Optimize validation performance with lazy SourceHint evaluation #2518
• Optimize CompositeBeanHelper performance with comprehensive caching #2526
• Optimize XmlPlexusConfiguration for performance and thread safety #2527
• Split user and system properties #2528
• Replace SoftIdentityMap with modern Cache implementation and add model object pooling #2529
• Fix MavenProject#getPlugin(String) performances #2530

[seregamorph]

I tried to use apache/maven-resolver#1508 and as I can see the problem is still there. Can you please confirm you have a better results for project generated via https://github.com/maven-turbo-reactor/maven-multiproject-generator ?

[XenoAmess]

I tried to use apache/maven-resolver#1508 and as I can see the problem is still there. Can you please confirm you have a better results for project generated via https://github.com/maven-turbo-reactor/maven-multiproject-generator ?

apache-maven-4.1.0-SNAPSHOT-bin.zip
@seregamorph if you trust me you can try this package and see if it be helpful.
on my local machines this package works better than maven-rc3......
well, we be improving it.
still, maybe it is slower than maven3 , because of the injection layer.
but things will be better when plugins start to use maven4 interfaces instead(which reduces the injection cost)

[cstamas]

Also, one big difference between mvn3 and mvn4 is transitive dep mgr in mvn4. In this respect, mvn4 will always be "a bit behind" maven3 and is okay, as long it is bearable overhead. To turn it off (and POM transformation) use -Dmaven.maven3Personality with Maven4.