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https://issues.apache.org/jira/browse/FLINK-9061?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16417964#comment-16417964
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Steve Loughran commented on FLINK-9061:
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[~greghogan]
I cut the link as it was just a duplicate of the one in the header.
your link is new; something I think I'd seen somewhere else too. It's
unfortunate that most of our knowledge here is superstition and stack traces,
but I think that's a deliberate attempt to avoid making any commitment about
future behaviour.
Here's my beliefs
#.Once you write enough data down a path, a partition is somehow triggered, and
data split across s3 shards
# that partitioning event is counted as part of your load for the bucket/the IO
which a partitioning path can sustain is reduced
# so the overall IO rate at that point drops. Maybe that's raising the 500 error
I don't think it partitions based purely on load. That would be fun given you
can just issue many delete requests to a path and get throttled.
> S3 checkpoint data not partitioned well -- causes errors and poor performance
> -----------------------------------------------------------------------------
>
> Key: FLINK-9061
> URL: https://issues.apache.org/jira/browse/FLINK-9061
> Project: Flink
> Issue Type: Bug
> Components: FileSystem, State Backends, Checkpointing
> Affects Versions: 1.4.2
> Reporter: Jamie Grier
> Priority: Critical
>
> I think we need to modify the way we write checkpoints to S3 for high-scale
> jobs (those with many total tasks). The issue is that we are writing all the
> checkpoint data under a common key prefix. This is the worst case scenario
> for S3 performance since the key is used as a partition key.
>
> In the worst case checkpoints fail with a 500 status code coming back from S3
> and an internal error type of TooBusyException.
>
> One possible solution would be to add a hook in the Flink filesystem code
> that allows me to "rewrite" paths. For example say I have the checkpoint
> directory set to:
>
> s3://bucket/flink/checkpoints
>
> I would hook that and rewrite that path to:
>
> s3://bucket/[HASH]/flink/checkpoints, where HASH is the hash of the original
> path
>
> This would distribute the checkpoint write load around the S3 cluster evenly.
>
> For reference:
> https://aws.amazon.com/premiumsupport/knowledge-center/s3-bucket-performance-improve/
>
> Any other people hit this issue? Any other ideas for solutions? This is a
> pretty serious problem for people trying to checkpoint to S3.
>
> -Jamie
>
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