Optimise memberlist kv store access by storing data unencoded. #4345
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
stevesg
force-pushed
the
memberlist-skip-decode
branch
from
4f4a480
to
48d67b7
Compare
pracucci
approved these changes
Jul 8, 2021
tomwilkie
approved these changes
Jul 8, 2021
The following profile data was taken from running 50 idle ingesters with
memberlist, with almost everything at default values (5s heartbeats):
```
52.16% mergeBytesValueForKey
+- 52.16% mergeValueForKey
+- 47.84% computeNewValue
+- 27.24% codec Proto Decode
+- 26.25% mergeWithTime
```
It is apparent from the this that a lot of time is spent on the memberlist
receive path, as might be expected, specifically, the merging of the update
into the current state. The cost however is not in decoding the incoming
states (occurs in `mergeBytesValueForKey` before `mergeValueForKey`), but
in fact decoding _current state_ of the value in the store (as it is stored
encoded). The ring state was measured at 123K (50 ingesters), so it makes
sense that decoding could be costly.
This can be avoided by storing the value in it's decoded `Mergeable` form.
When doing this, care has to be taken to deep copy the value when
accessed, as it is modified in place before being updated in the store,
and accessed outside the store mutex.
Note a side effect of this change is that is no longer straightforward
to expose the `memberlist_kv_store_value_bytes` metric, as this reported
the size of the encoded data, therefore it has been removed.
Signed-off-by: Steve Simpson <[email protected]>
Signed-off-by: Steve Simpson <[email protected]>
Signed-off-by: Steve Simpson <[email protected]>
auto-merge was automatically disabled
July 9, 2021 11:00
Head branch was pushed to by a user without write access
stevesg
force-pushed
the
memberlist-skip-decode
branch
from
214773e
to
30af11b
Compare
|
Manual tests results showed improved performances after this change, so let's get it merged. We can further re-iterate on follow up PRs. |
alvinlin123
pushed a commit
to ac1214/cortex
that referenced
this pull request
Jan 14, 2022
…xproject#4345) * Optimise memberlist kv store access by storing data unencoded. The following profile data was taken from running 50 idle ingesters with memberlist, with almost everything at default values (5s heartbeats): ``` 52.16% mergeBytesValueForKey +- 52.16% mergeValueForKey +- 47.84% computeNewValue +- 27.24% codec Proto Decode +- 26.25% mergeWithTime ``` It is apparent from the this that a lot of time is spent on the memberlist receive path, as might be expected, specifically, the merging of the update into the current state. The cost however is not in decoding the incoming states (occurs in `mergeBytesValueForKey` before `mergeValueForKey`), but in fact decoding _current state_ of the value in the store (as it is stored encoded). The ring state was measured at 123K (50 ingesters), so it makes sense that decoding could be costly. This can be avoided by storing the value in it's decoded `Mergeable` form. When doing this, care has to be taken to deep copy the value when accessed, as it is modified in place before being updated in the store, and accessed outside the store mutex. Note a side effect of this change is that is no longer straightforward to expose the `memberlist_kv_store_value_bytes` metric, as this reported the size of the encoded data, therefore it has been removed. Signed-off-by: Steve Simpson <[email protected]> * Typo. Signed-off-by: Steve Simpson <[email protected]> * Review comments. Signed-off-by: Steve Simpson <[email protected]> Signed-off-by: Alvin Lin <[email protected]>
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.
What this PR does:
The following profile data was taken from running 50 idle ingesters with
memberlist, with almost everything at default values (5s heartbeats):
It is apparent from the this that a lot of time is spent on the memberlist
receive path, as might be expected, specifically, the merging of the update
into the current state. The cost however is not in decoding the incoming
states (occurs in
mergeBytesValueForKeybeforemergeValueForKey), butin fact decoding current state of the value in the store (as it is stored
encoded). The ring state was measured at 123K (50 ingesters), so it makes
sense that decoding could be costly.
This can be avoided by storing the value in it's decoded
Mergeableform.When doing this, care has to be taken to deep copy the value when
accessed, as it is modified in place before being updated in the store,
and accessed outside the store mutex.
Note a side effect of this change is that is no longer straightforward
to expose the
memberlist_kv_store_value_bytesmetric, as this reportedthe size of the encoded data, therefore it has been removed.
Checklist
Documentation addedCHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX]