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https://issues.apache.org/jira/browse/FLINK-9061?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16422843#comment-16422843
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Steven Zhen Wu edited comment on FLINK-9061 at 4/2/18 5:50 PM:
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Usually 4-char random prefix can go a long way. Even 2-char random prefix can
be sufficient unless super high workload. Again, as Steve Loughran, nothing
official. just based on experience and speculation. But I think we should give
user the control the number of characters for the entropy part.
[~jgrier] flink checkpoint path is like
"s3://bucket/checkpoint-path-prefix/chk-121/random-UUID". So yes, reversing key
name can work, because last part is a random UUID. But I think we should give
user the control on the part of checkpoint path to introduce entropy. e.g. I
may want to maintain the top level prefixes (checkpoints and savepoints)
{code:java}
s3://bucket/checkpoints/<entropy>/rest-of-checkpoint-path
s3://bucket/savepoints/<entropy>/rest-of-savepointpoint-path{code}
was (Author: stevenz3wu):
Usually 4-char random prefix can go a long way. Even 2-char random prefix can
be sufficient unless super high workload. Again, as Steve Loughran, nothing
official. just based on experience and speculation. But I think we should give
user the control the number of characters for the entropy part.
[~jgrier] flink checkpoint path is like
"s3://bucket/checkpoint-path-prefix/chk-121/random-UUID". So yes, reversing key
name can work. But I think we should give user the control on the part of
checkpoint path to introduce entropy. e.g. I may want to maintain the top level
prefixes (checkpoints and savepoints)
{code:java}
s3://bucket/checkpoints/<entropy>/rest-of-checkpoint-path
s3://bucket/savepoints/<entropy>/rest-of-savepointpoint-path{code}
> 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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