[Performance / Resource Management WG] July Update

[Benjamin Mahler <bm...@apache.org>]

On the resource management front, Meng Zhu, Andrei Sekretenko, and myself
have been working on quota limits and enhancing multi-role framework
support:

- A memory leak in the allocator was fixed: MESOS-9852

- Support for quota limits work is well underway, and at this point the
major pieces are there and within the next few days it can be tried out.
The plan here is to try to push users towards using only quota limits, as
future support for optimistic offers will likely not support quota
guarantees.

- The /roles endpoint was fixed to expose all cases of "known" roles:
MESOS-9888 <https://issues.apache.org/jira/browse/MESOS-9888>, MESOS-9890
<https://issues.apache.org/jira/browse/MESOS-9890>.

- The /roles endpoint and roles table in the webui has been updated to
display quota consumption, as well as breakdowns of allocated, offered, and
reserved resources, see gif here:
https://reviews.apache.org/r/71059/file/1894/

- Several bugs were fixed for MULTI_ROLE framework support: MESOS-9856
<https://issues.apache.org/jira/browse/MESOS-9856>, MESOS-9870
<https://issues.apache.org/jira/browse/MESOS-9870>

- The v0 scheduler driver and java/python bindings are being updated to
support multiple roles.


On the performance front:

- MESOS-9755 <https://issues.apache.org/jira/browse/MESOS-9755>: William
Mahler and I looked into updating protobuf to 3.7.x from our existing 3.5.x
in order to attempt to use protobuf arenas in the master API and we noticed
a performance regression in the v0 /state endpoint. After looking into it,
it appears to be a performance regression in the protobuf reflection code
that we use to convert from our in-memory protobuf to json. No issue is
filed yet with the protobuf community, but it's worth also trying out
protobuf's built in json conversion code to see how that compares (see
MESOS-9896 <https://issues.apache.org/jira/browse/MESOS-9896>).


Feel free to reply with any questions or additional comments!

Ben