[SPARK-24815] Structured Streaming should support dynamic allocation

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.3.1
• Component/s: Scheduler, Spark Core, Structured Streaming
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Karthik Palaniappan
• Created: 16/Jul/18 01:22
• Updated: 4 days ago 18:35

Description

For batch jobs, dynamic allocation is very useful for adding and removing containers to match the actual workload. On multi-tenant clusters, it ensures that a Spark job is taking no more resources than necessary. In cloud environments, it enables autoscaling.

However, if you set spark.dynamicAllocation.enabled=true and run a structured streaming job, the batch dynamic allocation algorithm kicks in. It requests more executors if the task backlog is a certain size, and removes executors if they idle for a certain period of time.

Quick thoughts:

1) Dynamic allocation should be pluggable, rather than hardcoded to a particular implementation in SparkContext.scala (this should be a separate JIRA).

2) We should make a structured streaming algorithm that's separate from the batch algorithm. Eventually, continuous processing might need its own algorithm.

3) Spark should print a warning if you run a structured streaming job when Core's dynamic allocation is enabled

Issue Links

• links to: GitHub Pull Request #42352