[MESOS-5280] Inconsistent error checking in DRF sorter.

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: allocation
• Assignee: Yan Xu
• Reporter: Yan Xu
• Created: 25/Apr/16 23:19
• Updated: 08/Jun/16 17:27

Description

There exist a few different error handling styles in the sorter.

Hard checks

e.g., DRFSorter::update

CHECK(weights.contains(name));

No-op if it results in an error condition.

e.g., DRFSorter::allocated:

set<Client, DRFComparator>::iterator it = find(name);

if (it != clients.end()) { // TODO(benh): This should really be a CHECK.
...
}

The problem:

• Silence no-ops is not ideal. (Implicitness makes it hard to debug things and we have run into one instance of this).
• Hard CHECKs on invalid arguments is often too harsh.
• Not checking preconditions can lead to subtle bugs.
• We should check errors consistently.

Issue Links

• is related to: MESOS-5279 DRF sorter add/activate doesn't check if it's adding a duplicate entry