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Botong Huang updated YARN-7899: ------------------------------- Attachment: YARN-7899.v3.patch > [AMRMProxy] Stateful FederationInterceptor for pending requests > --------------------------------------------------------------- > > Key: YARN-7899 > URL: https://issues.apache.org/jira/browse/YARN-7899 > Project: Hadoop YARN > Issue Type: Sub-task > Reporter: Botong Huang > Assignee: Botong Huang > Priority: Major > Attachments: YARN-7899.v1.patch, YARN-7899.v3.patch, > YARN-7899.v3.patch > > > Today FederationInterceptor (in AMRMProxy for YARN Federation) is stateless > in terms of pending (outstanding) requests. Whenever AM issues new requests, > FI simply splits and sends them to sub-cluster YarnRMs and forget about them. > This JIRA attempts to make FI stateful so that it remembers the pending > requests in all relevant sub-clusters. This has two major benefits: > 1. It is a prerequisite for FI to be able to cancel pending request in one > sub-cluster and re-send it to other sub-clusters. This is needed for load > balancing and to fully comply with the relax locality fallback to ANY > semantic. When we send a request to one sub-cluster, we have effectively > restrained the allocation for this request to be within this sub-cluster > rather than everywhere. If the cluster capacity in this sub-cluster for this > app is full or this YarnRM is overloaded and slow, the request will be stuck > there for a long time even if there is free capacity in other sub-clusters. > We need FI to remember and adjust the pending requests on the fly. > 2. This makes pending request recovery easier when YarnRM fails over. Today > whenever one sub-cluster RM fails over, in order to recover lost pending > requests for this sub-cluster, > we have to propagate the ApplicationMasterNotRegisteredException from the > YarnRM back to AM, triggering a full pending resend from AM. This contains > pending for not only the failing-over sub-cluster, but everyone. Since our > split-merge (AMRMProxyPolicy) does not guarantee idempotency, the same > request we sent to sub-cluster-1 earlier might be resent to sub-cluster-2. If > both these YarnRMs have not failed over, they will both allocate for this > request, leading to over-allocation. Also, these full pending resends also > puts unnecessary load on every YarnRM in the cluster everytime one YarnRM > fails over. With stateful FederationInterceptor, since we remember pending > requests we have sent out earlier, we can shield the > ApplicationMasterNotRegisteredException for AM and resend the pending only to > the failed over YarnRM. This eliminates over-allocation and minimizes the > recovery overhead. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: yarn-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: yarn-issues-h...@hadoop.apache.org