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https://issues.apache.org/jira/browse/FLINK-5715?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15940602#comment-15940602
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ASF GitHub Bot commented on FLINK-5715:
---------------------------------------
Github user StefanRRichter commented on a diff in the pull request:
https://github.com/apache/flink/pull/3602#discussion_r107935639
--- Diff:
flink-tests/src/test/java/org/apache/flink/test/checkpointing/AbstractEventTimeWindowCheckpointingITCase.java
---
@@ -115,6 +117,14 @@ public static void stopTestCluster() {
@Before
public void initStateBackend() throws IOException {
switch (stateBackendEnum) {
+ case MEM_ASYNC:
+ this.stateBackend = new
AsyncMemoryStateBackend(MAX_MEM_STATE_SIZE);
+ break;
+ case FILE_ASYNC: {
+ String backups =
tempFolder.newFolder().getAbsolutePath();
+ this.stateBackend = new
AsyncFsStateBackend("file://" + backups);
--- End diff --
That is true. This similar issue should have been there, because this is
basically just copy-paste from the `case FILE`. I will fix both.
> Asynchronous snapshotting for HeapKeyedStateBackend
> ---------------------------------------------------
>
> Key: FLINK-5715
> URL: https://issues.apache.org/jira/browse/FLINK-5715
> Project: Flink
> Issue Type: New Feature
> Components: State Backends, Checkpointing
> Affects Versions: 1.3.0
> Reporter: Stefan Richter
> Assignee: Stefan Richter
> Fix For: 1.3.0
>
>
> Blocking snapshots render the HeapKeyedStateBackend practically unusable for
> many user in productions. Their jobs can not tolerate stopped processing for
> the time it takes to write gigabytes of data from memory to disk.
> Asynchronous snapshots would be a solution to this problem. The challenge for
> the implementation is coming up with a copy-on-write scheme for the in-memory
> hash maps that build the foundation of this backend. After taking a closer
> look, this problem is twofold. First, providing CoW semantics for the hashmap
> itself, as a mutible structure, thereby avoiding costly locking or blocking
> where possible. Second, CoW for the mutable value objects, e.g. through
> cloning via serializers.
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