[Java.Interop] use StringComparer.Ordinal for Dictionary #550
Conversation
This file contains hidden or 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
Context: https://docs.microsoft.com/en-us/dotnet/standard/base-types/best-practices-strings#ordinal-string-operations When profiling startup for a Xamarin.Forms app, I noticed some heavy calls to `Dictionary`: Total(ms) Self(ms) Calls Method name 392 49 14826 System.Collections.Generic.Dictionary`2<TKey_REF, TValue_REF>:FindEntry (TKey_REF) 377 18 12744 System.Collections.Generic.Dictionary`2<TKey_REF, TValue_REF>:TryGetValue (TKey_REF,TValue_REF&) 129 14 3827 System.Collections.Generic.Dictionary`2<TKey_REF, TValue_REF>:TryInsert (TKey_REF,TValue_REF,System.Collections.Generic.InsertionBehavior) Quite a few of these are coming from Java.Interop itself, and I noticed we were using the default constructor for `Dictionary`. This means we are using a culture-aware string comparison for every Java member we lookup. I could see a small difference in a Release build of the Xamarin.Forms integration project in xamarin-android: Before: 01-03 09:26:24.830 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +763ms 01-03 09:26:28.865 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +754ms 01-03 09:26:32.865 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +754ms 01-03 09:26:36.898 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +759ms 01-03 09:26:40.915 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +760ms 01-03 09:26:44.863 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +752ms 01-03 09:26:48.864 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +759ms 01-03 09:26:52.881 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +753ms 01-03 09:26:56.864 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +746ms 01-03 09:27:00.864 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +760ms Average(ms): 756 Std Err(ms): 1.60554594383897 Std Dev(ms): 5.07718207057594 After: 01-03 09:48:00.954 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +745ms 01-03 09:48:04.988 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +754ms 01-03 09:48:08.987 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +761ms 01-03 09:48:12.953 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +735ms 01-03 09:48:16.987 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +752ms 01-03 09:48:20.971 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +757ms 01-03 09:48:24.938 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +760ms 01-03 09:48:28.921 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +767ms 01-03 09:48:32.888 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +745ms 01-03 09:48:36.922 1473 1503 I ActivityTaskManager: Displayed Xamarin.Forms_Performance_Integration/xamarin.forms.performance.integration.MainActivity: +757ms Average(ms): 753.3 Std Err(ms): 2.97040962382856 Std Dev(ms): 9.39325999498222 I would guess this saves ~2ms to startup? I also toyed with changing the `capacity` value to 0, but that seemed to make things worse. I don't think there is a way for us to "guess" the default capacity for these dictionaries, so let's let the BCL do that.
jpobst
approved these changes
Jan 3, 2020
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
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.
Context: https://docs.microsoft.com/en-us/dotnet/standard/base-types/best-practices-strings#ordinal-string-operations
When profiling startup for a Xamarin.Forms app, I noticed some heavy
calls to
Dictionary:Quite a few of these are coming from Java.Interop itself, and I
noticed we were using the default constructor for
Dictionary. Thismeans we are using a culture-aware string comparison for every Java
member we lookup.
I could see a small difference in a Release build of the Xamarin.Forms
integration project in xamarin-android:
I would guess this saves ~2ms to startup?
I also toyed with changing the
capacityvalue to 0, but that seemedto make things worse. I don't think there is a way for us to "guess"
the default capacity for these dictionaries, so let's let the BCL do
that.