Instead of the master flag, why not a master API call. This will allow to update the value without restarting the master.
Another thought is that we should explain operators how and when to use this knob. For example, if they observe a behavioural pattern A, then it means B is happening, and tuning the knob to C might help. On Tue, Jun 12, 2018 at 7:36 AM, Jie Yu <[email protected]> wrote: > I would suggest we also consider the possibility of adding per framework > control on `min_allocatable_resources`. > > If we want to consider supporting per-framework setting, we should probably > model this as a protobuf, rather than a free form JSON. The same protobuf > can be reused for both master flag, framework API, or even supporting > Resource Request in the future. Something like the following: > > message ResourceQuantityPredicate { > enum Type { > SCALAR_GE, > } > optional Type type; > optional Value.Scalar scalar; > } > message ResourceRequirement { > required string resource_name; > oneof predicates { > ResourceQuantityPredicate quantity; > } > } > message ResourceRequirementList { > // All requirements MUST be met. > repeated ResourceRequirement requirements; > } > > // Resource request API. > message Request { > repeated ResoruceRequrementList accepted; > } > > // `allocatable()` > message MinimalAllocatableResources { > repeated ResoruceRequrementList accepted; > } > > On Mon, Jun 11, 2018 at 3:47 PM, Meng Zhu <[email protected]> wrote: > > > Hi: > > > > The allocatable > > <https://github.com/apache/mesos/blob/1.5.x/src/master/ > allocator/mesos/hierarchical.cpp#L2471-L2479> > > check in the allocator (shown below) was originally introduced to > > > > help alleviate the situation where a framework receives some resources, > > but no > > > > cpu/memory, thus cannot launch a task. > > > > > > constexpr double MIN_CPUS = 0.01;constexpr Bytes MIN_MEM = Megabytes(32); > > bool HierarchicalAllocatorProcess::allocatable( > > const Resources& resources) > > { > > Option<double> cpus = resources.cpus(); > > Option<Bytes> mem = resources.mem(); > > > > return (cpus.isSome() && cpus.get() >= MIN_CPUS) || > > (mem.isSome() && mem.get() >= MIN_MEM); > > } > > > > > > Issues > > > > However, there has been a couple of issues surfacing lately surrounding > > the check. > > > > - > > - - MESOS-8935 Quota limit "chopping" can lead to cpu-only and > > memory-only offers. > > > > We introduced fined-grained quota-allocation (MESOS-7099) in Mesos 1.5. > > When we > > > > allocate resources to a role, we'll "chop" the available resources of the > > agent up to the > > > > quota limit for the role. However, this has the unintended consequence of > > creating > > > > cpu-only and memory-only offers, even though there might be other agents > > with both > > > > cpu and memory resources available in the cluster. > > > > > > - MESOS-8626 The 'allocatable' check in the allocator is problematic with > > multi-role frameworks. > > > > Consider roleA reserved cpu/memory on an agent and roleB reserved disk on > > the same agent. > > > > A framework under both roleA and roleB will not be able to get the > > reserved disk due to the > > > > allocatable check. With the introduction of resource providers, the > > similar situation will > > > > become more common. > > > > Proposed change > > > > Instead of hardcoding a one-size-fits-all value in Mesos, we are > proposing > > to add a new master flag > > > > min_allocatable_resources. It specifies one or more scalar resources > > quantities that define the > > > > minimum allocatable resources for the allocator. The allocator will only > > offer resources that are more > > > > than at least one of the specified resources. The default behavior *is > > backward compatible* i.e. > > > > by default, the flag is set to “cpus:0.01|mem:32”. > > > > Usage > > > > The flag takes in either a simple text of resource(s) delimited by a bar > > (|) or a JSON array of JSON > > > > formatted resources. Note, the input should be “pure” scalar quantities > > i.e. the specified resource(s) > > > > should only have name, type (set to scalar) and scalar fields set. > > > > > > Examples: > > > > - - To eliminate cpu or memory only offer due to the quota chopping, > > - we could set the flag to “cpus:0.01;mem:32” > > - > > - - To enable offering disk only offer, we could set the flag to > > “disk:32” > > - > > - - For both, we could set the flag to “cpus:0.01;mem:32|disk:32”. > > - Then the allocator will only offer resources that at least contain > > “cpus:0.01;mem:32” > > - OR resources that at least contain “disk:32”. > > > > > > Let me know what you think! Thanks! > > > > > > -Meng > > > > >
