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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/35702/
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(Updated Sept. 4, 2015, 11:19 p.m.)
Review request for mesos, Adam B, Benjamin Hindman, Ben Mahler, Jie Yu, Joris
Van Remoortere, and Vinod Kone.
Changes
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Rebased. NNFR.
Bugs: MESOS-2600
https://issues.apache.org/jira/browse/MESOS-2600
Repository: mesos
Description
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This involved a lot more challenges than I anticipated, I've captured the
various approaches and limitations and deal-breakers of those approaches here:
[Master Endpoint Implementation
Challenges](https://docs.google.com/document/d/1cwVz4aKiCYP9Y4MOwHYZkyaiuEv7fArCye-vPvB2lAI/edit#)
Key points:
* This is a stop-gap solution until we shift the offer creation/management
logic from the master to the allocator.
* `updateAvailable` and `updateSlave` are kept separate because
(1) `updateAvailable` is allowed to fail whereas `updateSlave` must not.
(2) `updateAvailable` returns a `Future` whereas `updateSlave` does not.
(3) `updateAvailable` never leaves the allocator in an over-allocated state
and must not, whereas `updateSlave` does, and can.
* The algorithm:
* Initially, the master pessimistically assume that what seems like
"available" resources will be gone.
This is due to the race between the allocator scheduling an `allocate`
call to itself vs master's
`allocator->updateAvailable` invocation.
As such, we first try to satisfy the request only with the offered
resources.
* We greedily rescind one offer at a time until we've rescinded
sufficiently many offers.
IMPORTANT: We perform `recoverResources(..., Filters())` which has a
default `refuse_sec` of 5 seconds,
rather than `recoverResources(..., None())` so that we can virtually
always win the race against `allocate`.
In the rare case that we do lose, no disaster occurs. We simply fail to
satisfy the request.
* If we still don't have enough resources after resciding all offers, be
semi-optimistic and forward the
request to the allocator since there may be available resources to
satisfy the request.
* If the allocator returns a failure, report the error to the user with
`Conflict`.
This approach is clearly not ideal, since we would prefer to rescind as little
offers as possible.
Diffs (updated)
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src/master/http.cpp 94e97a2898106579434e8cdec04b7b0e130a810e
src/master/master.hpp e1331851c19e3372a4a525dcfd7ba2a01c3e97a6
src/master/master.cpp 5589eca4317b597de509f3387cfc349083b361ac
src/master/validation.hpp 43b8d84556e7f0a891dddf6185bbce7ca50b360a
src/master/validation.cpp ffb7bf07b8a40d6e14f922eabcf46045462498b5
Diff: https://reviews.apache.org/r/35702/diff/
Testing
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`make check`
Thanks,
Michael Park
