Hi Robert,

I do not exactly understand what's wrong with the current implementation. throttle() step works well without Parallel, e.g. the following sample works well:

throttle(['test_2']) {
  node() {
        sh "sleep 500"
        echo "Done"
  }
}

The thing is that the Pipeline actually starts, but node() step will synchronize on the category

Anyway, it worth providing such example in the docs

I have done the following:
case (target_option != "HOST" && comp_tool == "ARM"):
throttle(['ARM_LICENSES'])
{
stage("Build libraries")
{
try
{
sh ''' mkdir BUILD
cd BUILD
cmake -GNinja -DCTEST_GENERATE_XUNIT_FILES=ON -DCMAKE_TOOLCHAIN_FILE=$CBS/toolchains/ARMCortexR4Toolchain.cmake -DCBS_RUN_VPUML=OFF ${WORKSPACE}/sdmos/cmake/targets/repository
ninja -v '''
currentBuild.result = "${env.job_pass}"
}
catch (Exception err)
{
currentBuild.result = "${env.job_fail}"
CommonUtilities.stage_failure("Build libraries")
println err
throw err
}
}
}

If it set ARM_LICENSES to 2 in Jenkins config then trigger threee pipelines that has this in I see all three jobs running the build stage at the same time.
Do I need to move to beore the node as in the example?

Yes, throttling will work on the node() level only. so the node() definition should be within the throttle() block.

abayer just to be flexible with support of other throttling scopes, maybe we could add something like a  ThrottlePlaceholderTask? Maybe a flyweight one... It would be similar with node() acquisition logic, which is not a state of the art design though. But it would help. WDYT?

Ok if I put it before node then the other job waits.
Thanks for the help

If you do not mind, let's keep this bug open. I will discuss it with abayer and probably convert it to RFE

Created https://github.com/jenkinsci/throttle-concurrent-builds-plugin/pull/49 with documentation improvements. rob_squire I will appreciate feedback in the pull request.

Regarding this issue, I am going to convert it to RFE