Modify Hive external table scan scheduling strategy #1394
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
stdpain
changed the title
stdpain
changed the title
In the previous scan scheduling, if there were multiple partitions, each partition would be scanned equally, and although this would allow each scanner to be scheduled very equally, it would also result in too many HDFS files being open at the same time. In some scenarios several thousand HDFS handles may be held at the same time. It will increase the load on HDFS.
dirtysalt
previously approved these changes
Nov 22, 2021
kangkaisen
reviewed
Nov 22, 2021
dirtysalt
approved these changes
Nov 22, 2021
|
run starrocks_be_unittest |
kangkaisen
approved these changes
Nov 23, 2021
stdpain
added a commit
to stdpain/starrocks-2
that referenced
this pull request
Nov 23, 2021
kangkaisen
pushed a commit
that referenced
this pull request
Nov 23, 2021
stdpain
added a commit
to stdpain/starrocks-2
that referenced
this pull request
Dec 3, 2021
kangkaisen
pushed a commit
that referenced
this pull request
Dec 3, 2021
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In the previous scan scheduling, if there were multiple partitions, each partition would be scanned equally,
and although this would allow each scanner to be scheduled very equally, it would also result in too many HDFS files being open at the same time.
In some scenarios several thousand HDFS handles may be held at the same time. It will increase the load on HDFS.
Now we will limit max_hdfs_file_instance in hive external table, if opened file greater than this. scanner will push back to pending list
if opened file greater than this. scanner will push back to pending list. We can't have all scanners in the pending state, we need to make sure there is at least one thread on each SCAN NODE that can be running