James DeFelice created MESOS-9313:
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Summary: Document speculative offer operation semantics for
framework writers.
Key: MESOS-9313
URL: https://issues.apache.org/jira/browse/MESOS-9313
Project: Mesos
Issue Type: Documentation
Reporter: James DeFelice
It recently came to my attention that a subset of offer operations (e.g.
RESERVE, UNRESERVE, et al.) are implemented speculatively within mesos master.
Meaning that the master will apply the resource conversion internally
**before** the conversion is checkpointed on the agent. The master may then
re-offer the converted resource to a framework -- even though the agent may
still not have checkpointed the resource conversion. If the checkpointing
process on the agent fails, then subsequent operations issued for the
falsely-offered resource will fail. Because the master essentially "lied" to
the framework about the true state of the supposedly-converted resource.
It's also been explained to me that this case is expected to be rare. However,
it *can* impact the design/implementation of framework state machines and so
it's critical that this information be documented clearly - outside of the C++
code base.
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