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https://issues.apache.org/jira/browse/FLINK-10461?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16667356#comment-16667356
]
ASF GitHub Bot commented on FLINK-10461:
----------------------------------------
azagrebin commented on a change in pull request #6777: [FLINK-10461] [State
Backends, Checkpointing] Speed up download files when restore from DFS
URL: https://github.com/apache/flink/pull/6777#discussion_r228964472
##########
File path:
flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBStateBackend.java
##########
@@ -235,9 +238,10 @@ public RocksDBStateBackend(StateBackend
checkpointStreamBackend) {
* @param checkpointStreamBackend The backend write the checkpoint
streams to.
* @param enableIncrementalCheckpointing True if incremental
checkpointing is enabled.
*/
- public RocksDBStateBackend(StateBackend checkpointStreamBackend,
TernaryBoolean enableIncrementalCheckpointing) {
+ public RocksDBStateBackend(StateBackend checkpointStreamBackend,
TernaryBoolean enableIncrementalCheckpointing, int restoreThreadNum) {
Review comment:
I would also leave the previous method without restoreThreadNum:
```
public RocksDBStateBackend(StateBackend checkpointStreamBackend,
TernaryBoolean enableIncrementalCheckpointing) {
this(checkpointStreamBackend, enableIncrementalCheckpointing, -1);
}
```
this way we do not break existing code, including other methods here, like
this modification which is not needed then and other similar ones:
```
public RocksDBStateBackend(StateBackend checkpointStreamBackend) {
this(checkpointStreamBackend, TernaryBoolean.UNDEFINED, 1);
}
```
and I would rather keep it undefined here, e.g. `-1`, similar to
`TernaryBoolean.UNDEFINED` for `enableIncrementalCheckpointing`. It can be
resolved then in `private RocksDBStateBackend(RocksDBStateBackend original,
Configuration config)` and `getRestoreThreadNum`.
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> Speed up download file procedure when restore
> ----------------------------------------------
>
> Key: FLINK-10461
> URL: https://issues.apache.org/jira/browse/FLINK-10461
> Project: Flink
> Issue Type: Improvement
> Components: State Backends, Checkpointing
> Reporter: Congxian Qiu
> Assignee: Congxian Qiu
> Priority: Major
> Labels: pull-request-available
>
> In the current master branch, the restore will download file from DFS, the
> download procedure are single-thread, this could speed up by using
> multi-thread for downloading states from DFS.
>
> In my company, the states will come to some terabytes, so the restore
> procedure will become a litter slow, after a bit digging, I find download
> states from DFS using single thread, this could using multi-thread for speed
> up.
> I test the time used for download states from DFS with ~2 terabytes states.
> With single thread it used 640+s, and 130+s when using 5 threads for download.
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