Threads parameter is not working on Apple Silicon

[orpiske]

Obs.: I'm opening a ticket for an issue I noticed while the support for M1 was not yet official. I noticed that this still seem to be happening. Back then, I wrote the following report:

    I know support is not official yet, but sharing my experience in the hope it will eventually be useful for when there is an official release. 

One thing I noticed is that the build for ARM doesn't seem to respect the mvnd.threads setting or the -T flag. Using -T 0.5C here, still causes it to use all cores.

Originally posted by @orpiske in #337 (comment)

[gnodet]

Can you reproduce the issue ?
Are you sure you don't have the mvnd.threads property set in one of the configuration file ?
It seems to work correctly for me...

[orpiske]

@gnodet my [USER_HOME]/.m2/mvnd.properties has mvnd.threads=0.5C. My understanding is that it would use half of the available cores by default. Is there something else I should look at that could be affecting this?

[gnodet]

I've set my [USER_HOME]/.m2/mvnd.properties to add mvnd.threads=0.5C and it works fine for me.
Can you check your environment maybe using set | grep MAVEN ?
mvnd also checks the [PROJECT_HOME]/.mvn/mvnd.properties and [MVND_HOME]/conf/mvnd.properties...

[orpiske]

@gnodet thanks. This is what I have:

MAVEN_OPTS=-Xms2048m -Xmx3584m
MAVEN_HOME=/Users/opiske/.sdkman/candidates/maven/current

My mvnd.properties from MVND_HOME seems to use the default values:

cat $MVND_HOME/conf/mvnd.properties | grep -i thread
# MVND_MIN_THREADS
# The minimum number of threads to use when constructing the default {@code -T} parameter for the daemon.
# This value is ignored if @{@code -T}, @{@code --threads} or {@code -Dmvnd.threads} is specified on the command
# line, or if {@code mvnd.threads} is specified in {@code ~/.m2/mvnd.properties}.
# mvnd.minThreads = 1
# MVND_THREADS
# The number of threads to pass to the daemon; same syntax as Maven's {@code -T}/{@code --threads} option. Ignored
# if the user passes @{@code -T}, @{@code --threads} or {@code -Dmvnd.threads} on the command
# mvnd.threads =
# MVND_THREAD_STACK_SIZE
# JVM options for the daemon to specify the thread stack size
# mvnd.threadStackSize = 1M

And looking at one of my projects, this is what I have:

ls ~/code/java/camel/.mvn
extensions.xml  jvm.config      wrapper/

[orpiske]

I think I know where the problem may be: the log message correctly displays the scaled down number of threads as I adjust the setting, however the CPU load pattern on both htop and on Activity Monitor seems to imply that the load is happening on all Cores.

I am not sure if the problem is indeed w/ Maven Daemon. Maybe it's something specific about how the scheduler distributes the load on this OS/platform.

So, I think we can close this @gnodet.