@InterfaceAudience.Public @InterfaceStability.Evolving public abstract class PreemptionMessage extends Object
PreemptionMessage is part of the RM-AM protocol, and it is used by
 the RM to specify resources that the RM wants to reclaim from this
 ApplicationMaster (AM). The AM receives a StrictPreemptionContract message encoding which containers the platform may
 forcibly kill, granting it an opportunity to checkpoint state or adjust its
 execution plan. The message may also include a PreemptionContract
 granting the AM more latitude in selecting which resources to return to the
 cluster.
 
 The AM should decode both parts of the message. The StrictPreemptionContract specifies particular allocations that the RM
 requires back. The AM can checkpoint containers' state, adjust its execution
 plan to move the computation, or take no action and hope that conditions that
 caused the RM to ask for the container will change.
 
 In contrast, the PreemptionContract also includes a description of
 resources with a set of containers. If the AM releases containers matching
 that profile, then the containers enumerated in PreemptionContract.getContainers() may not be killed.
 
Each preemption message reflects the RM's current understanding of the cluster state, so a request to return N containers may not reflect containers the AM is releasing, recently exited containers the RM has yet to learn about, or new containers allocated before the message was generated. Conversely, an RM may request a different profile of containers in subsequent requests.
The policy enforced by the RM is part of the scheduler. Generally, only containers that have been requested consistently should be killed, but the details are not specified.
| Constructor and Description | 
|---|
| PreemptionMessage() | 
| Modifier and Type | Method and Description | 
|---|---|
| abstract PreemptionContract | getContract() | 
| abstract StrictPreemptionContract | getStrictContract() | 
| static PreemptionMessage | newInstance(StrictPreemptionContract set,
           PreemptionContract contract) | 
| abstract void | setContract(PreemptionContract contract) | 
| abstract void | setStrictContract(StrictPreemptionContract set) | 
@InterfaceAudience.Private @InterfaceStability.Unstable public static PreemptionMessage newInstance(StrictPreemptionContract set, PreemptionContract contract)
@InterfaceAudience.Public @InterfaceStability.Evolving public abstract StrictPreemptionContract getStrictContract()
ResourceManager@InterfaceAudience.Private @InterfaceStability.Unstable public abstract void setStrictContract(StrictPreemptionContract set)
@InterfaceAudience.Public @InterfaceStability.Evolving public abstract PreemptionContract getContract()
@InterfaceAudience.Private @InterfaceStability.Unstable public abstract void setContract(PreemptionContract contract)
Copyright © 2008–2023 Apache Software Foundation. All rights reserved.