Add 8.0 synchronous batching breaking change section #368
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
Fix style issues
vonzshik
reviewed
Oct 3, 2024
| @@ -64,6 +64,27 @@ Version 8.0 contains many other smaller features and bug fixes, [see the 8.0.0 m | |||
|
|
|||
| ## Breaking changes | |||
|
|
|||
| ### Synchronous command batching can cause threadpool starvation | |||
|
|
|||
| To allow Npgsql to write command batches containing large data payloads (generally parameter data) synchronously, without running into PostgreSQL limitations, it runs any commands after the first asynchronously. This introduces sync over async and can cause threadpool starvation at higher loads. In Npgsql versions prior to 8.0 a workaround was in place that would mitigate the effects of this sync over async, allowing most higher loads to run succesfully. This workaround was removed to make room for the far reaching NativeAOT refactor. | |||
There was a problem hiding this comment.
Should probably add a few examples how threadpool starvation affects users, like delayed query execution time and even timeouts.
roji
approved these changes
Oct 4, 2024
| * Use [ThreadPool.SetMinThreads()](https://learn.microsoft.com/en-us/dotnet/api/system.threading.threadpool.setminthreads?view=net-8.0) to expand the minimum pool of threads available for blocking. | ||
| * Refactor code using command batches to use asynchronous apis. | ||
|
|
||
| If these options are not suitable for your project you can consider opening an issue on [https://github.com/npgsql/npgsql](https://github.com/npgsql/npgsql). This helps us prioritize the effort to bring back some mitigation in a patch version. |
There was a problem hiding this comment.
Maybe direct people to a specific issue (like the one that triggered this breaking change note) to avoid new duplicate issues getting opened etc.
|
|
||
| If these options are not suitable for your project you can consider opening an issue on [https://github.com/npgsql/npgsql](https://github.com/npgsql/npgsql). This helps us prioritize the effort to bring back some mitigation in a patch version. | ||
|
|
||
| To clarify, Npgsql 8.0 has not dropped support for synchronous command batches completely; the feature is entirely supported for use at low load or for local data exploration. |
There was a problem hiding this comment.
Is that maybe a bit too harsh? Given the workaround (e.g. SetMinThreads()) it's possible to do this even at higher load, it's just up to the user to preconfigure things etc?
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.
No description provided.