Details
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Bug
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Status: Resolved (View Workflow)
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Minor
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Resolution: Not A Defect
Description
When using a parallel step for an indexed loop, using the loop-iterator-index for internal usage results with wrong value (showing the max-index-value for all iterations).
A workaround for it is to set a local variable for saving the current iteration-index and use the local variable.
The following pipeline demonstrates the problem (the issue is demonstrated with the internal 'echo' steps):
pipeline
{
agent any
stages
{
stage('Explore bug')
{
steps
{
script
{
int maxIndex1=3
def loopers1 = [:]
for (int loopIndex1 = 0; loopIndex1 < maxIndex1; loopIndex1++)
{
echo "loopIndex1=${loopIndex1}"
loopers1["loop-$\{loopIndex1}"] =
{
echo "loopIndex1=${loopIndex1}"
}
}
parallel loopers1
}
}
}
stage('Bug workaround')
{
steps
{
script
{
int maxIndex2=3
def loopers2 = [:]
for (int loopIndex2 = 0; loopIndex2 < maxIndex2; loopIndex2++)
{
int index2=loopIndex2
echo "index2=${index2}"
loopers2["loop-$\{index2}"] =
{
echo "index2=${index2}"
}
}
parallel loopers2
}
}
}
}
}
Attachments
Activity
This is just how Groovy works I am afraid. Java 8 allows for effectively-final variables, and signals a compilation error if the variable is not effectively final, but Groovy merrily compiles an incorrect program.
Someone showed me this: https://jenkins.io/doc/pipeline/examples/#parallel-from-list which explains that this is not a bug but a feature (loopIndex1 byRef not byVal)). Still, I think that intuitively it looks like a bug since I expect it to behave in one way while it acts differently.