[HADOOP-13029] Have FairCallQueue try all lower priority sub queues before backoff

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: ipc
• Labels: qos rpc
• Assignee: Unassigned
• Reporter: Ming Ma
• Created: 15/Apr/16 23:52
• Updated: 28/Mar/22 11:35

Description

Currently if FairCallQueue and backoff are enabled, backoff will kick in as soon as the assigned sub queue is filled up.

  /**
   * Put and offer follow the same pattern:
   * 1. Get the assigned priorityLevel from the call by scheduler
   * 2. Get the nth sub-queue matching this priorityLevel
   * 3. delegate the call to this sub-queue.
   *
   * But differ in how they handle overflow:
   * - Put will move on to the next queue until it lands on the last queue
   * - Offer does not attempt other queues on overflow
   */

Seems it is better to try lower priority sub queues when the assigned sub queue is full, just like the case when backoff is disabled. This will give regular users more opportunities and allow the cluster to be configured with smaller call queue length. chrili, arpitagarwal, what do you think?

Issue Links

• is related to: HADOOP-9640 RPC Congestion Control with FairCallQueue