Fixes opt-out for scripted batch execution #6054
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eed3si9n
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Nov 3, 2020
scripted-sbt-redux/src/main/scala/sbt/scriptedtest/ScriptedTests.scala
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eed3si9n
previously approved these changes
Nov 3, 2020
eed3si9n
previously approved these changes
Nov 3, 2020
When 1 is passed in as the sbtInstances argument to runInParallel, all of the tests get batched together in a single sbt session. The run methods in ScriptedRunner were delegating to runInParallel and as a result were causing all of the tests to be batched, which was not how it used to work in sbt 1.3.x. To fix this we can instead pass in Int.MaxValue for the number of sbt instances. The Int.MaxValue parameter causes the batch size to be set to 1 in the batchScriptedRunner method which causes the scriptedRunners variable to have the same size as the number of tests. We then can prevent a parallel array from being used if the sbtInstances is deteced to be the Int.MaxValue sentinel.
sbt itself effectively runs its scripted test with scriptedBatchExecution true and scriptedParallelInstances 1. The performance is much better when this works. This can cause issues, see #6042, but we inadvertently made this behavior the default in 1.4.0 and it took about a month before #6042 was reported so I think most users would benefit from this default.
eed3si9n
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scriptedBatchExecution := false semantics
This was referenced Nov 16, 2020
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sbt 1.4.0 made batch execution the default behavior. The following setting can be used to opt out of the behavior:
To increase parallelism use:
original description
This PR makes the scripted plugin work the way it used to in older sbt versions when
scriptedBatchExecution := false. It also makesscriptedBatchExecution := truethe default because I think the performance improvement is worth it for most builds even though it can cause issues like in #6042. I can remove the second commit if there is disagreement on changing the default.