We ran into this issue whilst attempting to run a pipeline that has highly parallel build steps.
In this instance drone is responsible for deploying an application across a number of contexts.
The pipeline ran but numerous build steps were incorrectly marked as Success. These builds steps were not run, did not deploy the service and left no logs. I have attached an image of one of the failing build steps. Our investigation determined that these errors were taking place when running highly parallel builds on a system limited by threadcount.
Given the fact that the deployment was in an very inconsistent state and in fact partial it should never report GREEN
We were able to mitigate the issue itself by limiting the ‘MAX_PROCS’ running so that parallel pipelines no longer caused the error but this was at the cost of their concurrency and as such the gains provided by it.