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Bug
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Resolution: Fixed
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Major
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None
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Jenkins 1.618
Workflow 1.8
While experimenting with Workflow, I called the equivalent of
parallel [:]
This appears to have never terminated.
Specifically, "Execute sub-workflows in parallel : Start" has been running for 14 hours now, with no child steps.
- depends on
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JENKINS-25550 Hard kill
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- Resolved
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- is duplicated by
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- Resolved
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- links to
[JENKINS-29413] Parallel with an empty map will run forever
Chris Hillery
added a comment - FYI the workaround on JENKINS-25550 (appending /doDelete to the build URL) doesn't work either. It removes the build in that the URL for the build returns 404, but the "part of foo" build is still consuming an executor on the slave.
Chris Hillery
added a comment - FYI the workaround on JENKINS-25550 (appending /doDelete to the build URL) doesn't work either. It removes the build in that the URL for the build returns 404, but the "part of foo" build is still consuming an executor on the slave. Chris Hillery
added a comment - Also FYI, even deleting the Workflow itself doesn't fix it. Executors still in use (although that at least cleared any queued runs).
Chris Hillery
added a comment - Also FYI, even deleting the Workflow itself doesn't fix it. Executors still in use (although that at least cleared any queued runs). Chris Hillery
added a comment - Ahh... deleting the Workflow job, and then stopping and starting Jenkins finally did the trick. All executors free, and the phantom slave is gone.
(FYI I initially tried to use the <jenkins>/restart URL to restart Jenkins, and the Java process went into a 100% CPU busyloop. But killing it and restarting Jenkins finally put things right.)
This is still a pretty severe consequence of a trivial bug in a workflow script.
Chris Hillery
added a comment - Ahh... deleting the Workflow job, and then stopping and starting Jenkins finally did the trick. All executors free, and the phantom slave is gone.
(FYI I initially tried to use the <jenkins>/restart URL to restart Jenkins, and the Java process went into a 100% CPU busyloop. But killing it and restarting Jenkins finally put things right.)
This is still a pretty severe consequence of a trivial bug in a workflow script. You need to delete the build as mentioned in JENKINS-25550, then restart.
Chris Hillery
added a comment - Good to know the work-around, but IMHO at least this is still a significant bug as the consequences are severe and the work-around is pretty hidden.
Chris Hillery
added a comment - Good to know the work-around, but IMHO at least this is still a significant bug as the consequences are severe and the work-around is pretty hidden. 
Jens Wilke
added a comment - Although obvious for the Groovy hackers, the workaround is:
def possiblyEmptyArray = ...
if (possiblyEmptyArray) {
parallel possiblyEmptyArray
}
Jens Wilke
added a comment - Although obvious for the Groovy hackers, the workaround is:
def possiblyEmptyArray = ...
if (possiblyEmptyArray) {
parallel possiblyEmptyArray
}
Code changed in jenkins
User: Jesse Glick
Path:
CHANGES.md
aggregator/src/test/java/org/jenkinsci/plugins/workflow/steps/parallel/ParallelStepTest.java
cps/src/main/java/org/jenkinsci/plugins/workflow/cps/steps/ParallelStepExecution.java
http://jenkins-ci.org/commit/workflow-plugin/1ecc56e967940fbc6047aa432d5d5e556670eca2
Log:
[FIXED JENKINS-29413]: hung build when running the parallel step with an empty map.
Code changed in jenkins
User: Jesse Glick
Path:
CHANGES.md
aggregator/src/test/java/org/jenkinsci/plugins/workflow/steps/parallel/ParallelStepTest.java
cps/src/main/java/org/jenkinsci/plugins/workflow/cps/steps/ParallelStepExecution.java
http://jenkins-ci.org/commit/workflow-plugin/85330f60060d84c9d4d5b05a2062e9fc97063a74
Log:
Merge pull request #265 from jglick/parallel-JENKINS-29413
JENKINS-29413 Hung build when running the parallel step with an empty map
Compare: https://github.com/jenkinsci/workflow-plugin/compare/be558db587b9...85330f60060d
Code changed in jenkins
User: Jesse Glick
Path:
aggregator/src/test/java/org/jenkinsci/plugins/workflow/steps/parallel/ParallelStepTest.java
cps/src/main/java/org/jenkinsci/plugins/workflow/cps/steps/ParallelStepExecution.java
http://jenkins-ci.org/commit/workflow-cps-plugin/bd606c258e887f8b7f9fa4bab9de0d008541d524
Log:
[FIXED JENKINS-29413]: hung build when running the parallel step with an empty map.
Originally-Committed-As: 1ecc56e967940fbc6047aa432d5d5e556670eca2
Recommend increasing the priority, as this bug can render your Jenkins installation unusable and unrecoverable.
I ran the following workflow:
def nothing = [:]
node {
parallel nothing
}
and now there is a "build" consuming one executor on a slave. This build cannot be killed and survives Jenkins restarts. Even deleting the slave entirely cannot recover the situation. Nothing short of nuking JENKINS_HOME from orbit seems to get rid of it.
Clearly this workflow is silly, but it would be pretty easy to do the equivalent accidentally if your Groovy script dynamically built up a set of blocks to run (like the "splitTests" demo in the documentation does). And the consequences currently are pretty dire.