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https://issues.apache.org/jira/browse/FLINK-9061?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16589873#comment-16589873
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ASF GitHub Bot commented on FLINK-9061:
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StefanRRichter commented on a change in pull request #6604: [FLINK-9061]
Optionally add entropy to checkpoint paths better S3 scalability
URL: https://github.com/apache/flink/pull/6604#discussion_r212216578
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/state/filesystem/CheckpointPathFilter.java
##########
@@ -0,0 +1,53 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
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+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+ */
+
+package org.apache.flink.runtime.state.filesystem;
+
+import org.apache.flink.core.fs.Path;
+
+/**
+ * A transformer that may modify paths for checkpoint data and metadata files.
+ */
+public interface CheckpointPathFilter {
Review comment:
`PathTransformer` might be a better name for what it does (see your own
comment).
I also wonder if we could simply collapse the separation path + transformer
into a `PathProvider` or `PathFactory` and we could have one for data and one
for meta data. This can be a bit tricky for `FsCheckpointStorageLocation`, but
also the current solution seems problematic.
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> add entropy to s3 path for better scalability
> ---------------------------------------------
>
> Key: FLINK-9061
> URL: https://issues.apache.org/jira/browse/FLINK-9061
> Project: Flink
> Issue Type: Bug
> Components: FileSystem, State Backends, Checkpointing
> Affects Versions: 1.5.0, 1.4.2
> Reporter: Jamie Grier
> Assignee: Indrajit Roychoudhury
> Priority: Critical
> Labels: pull-request-available
>
> 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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