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Parallelism in Jenkins is defined at the Stage level which means that…
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that a single Jenkins Pipeline is invoked, containing…
Some Stages configured to run sequentially
with each Step within those Stages running sequentially(with their component Steps running sequentially), and/or
Some Stages
configureconfigured to run concurrently
with each Step within those Stages(with their component Steps running sequentially)
See Parallel stages with Declarative Pipeline 1.2 (jenkins.io)
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