mesos-reviews mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Michael Park" <>
Subject Re: Review Request 35702: Added /reserve HTTP endpoint to the master.
Date Tue, 28 Jul 2015 21:03:45 GMT

This is an automatically generated e-mail. To reply, visit:

(Updated July 28, 2015, 9:03 p.m.)

Review request for mesos, Adam B, Benjamin Hindman, Ben Mahler, Jie Yu, Joris Van Remoortere,
and Vinod Kone.


Only rescind offers if rescinding the offer will contribute in satisfying the request

Bugs: MESOS-2600

Repository: mesos


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

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    * We greedily rescind one offer at a time until we've rescinded sufficiently many offers.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())` rather than `recoverResources(...,
None())` so that we can pretty much always win the race against `allocate`.
                 In the case that we lose, no disaster occurs. We simply fail to satisfy the
    * If we still don't have enough resources after resciding all offers, be optimistic and
forward the request to the allocator since there may be available resources to satisfy the
    * If the allocator returns a failure, report the error to the user with `PreconditionFailed`.
This could be updated to be `Forbidden`, or `Conflict` maybe as well. We'll pick one eventually.

This approach is clearly not ideal, since we would prefer to rescind as little offers as possible.
The challenges of implementing the ideal solution in the current state is described in the
document above.

TODO(mpark): Add more comments and test cases.

Diffs (updated)

  src/master/http.cpp 3a1598fad4db03e5f62fd4a6bd26b2bedeee4070 
  src/master/master.hpp 827d0d599912b2936beb9615610f627f6c9a2d43 
  src/master/master.cpp 5b5e3c37d4433c8524db267866aebc0a35a181f1 
  src/master/validation.hpp 469d6f56c3de28a34177124aae81ce24cb4ad160 
  src/master/validation.cpp 9d128aa1b349b018b8e4a1916434d848761ca051 



`make check`


Michael Park

  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message