[HADOOP-18517] ABFS: Add fs.azure.enable.readahead option to disable readahead

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.3.4
• Fix Version/s: 3.4.0, 3.3.5
• Component/s: fs/azure
• Labels: pull-request-available
• Target Version/s: 3.3.5
• Hadoop Flags: Reviewed
• Assignee: Steve Loughran
• Reporter: Steve Loughran
• Created: 02/Nov/22 16:22
• Updated: 27/Jan/24 09:05
• Resolved: 08/Nov/22 13:50

Description

Add an option fs.azure.enable.readahead to allow the abfs readahead to be disabled.

This has been shipping in cloudera releases, because workloads with heavy random IO don't always benefit from prefetching.

Pulling this in to ASF hadoop allows for

• everyone to experiment with/without prefetching
• ability to disable prefetching if you have problems with it

Issue Links

• relates to: HADOOP-18521 ABFS ReadBufferManager buffer sharing across concurrent HTTP requests
• links to: GitHub Pull Request #5103