Creation of scroll container with 30 paragraphs is super slow on Android #6124
Description
Checklist
- I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
- This issue only relates to a single bug. I will open new issues for any other problems.
Describe the bug
When I create an Android app with 30 paragraphs (from NewRichTextFromMarkdown) in a NewVScroll container, the app takes over 10 seconds to start.
Example app for testing: Render test
The function call of createRichText() takes 6 to 8 seconds. When I comment out textArea.Refresh(), it takes only 1 ms. Thus all time is used by Refresh(). In any case the app needs 10 seconds until the Markdown content shows up.
How to reproduce
- Download Render test.
- Add an icon file.
fyne package --os android --release && fyne install --os android- Start app on Android device.
Screenshots
No response
Example code
See Render test.
Fyne version
develop branch
Go compiler version
1.25.7
Operating system and version
Arch Linux
Additional Information
Profiling of the createRichText() call:
$ go tool pprof -top ./cpu1.pprof
...
Type: cpu
Time: 2026-02-21 10:21:33 CET
Duration: 6.54s, Total samples = 6.74s (103.06%)
Showing nodes accounting for 5.88s, 87.24% of 6.74s total
Dropped 142 nodes (cum <= 0.03s)
flat flat% sum% cum cum%
0.81s 12.02% 12.02% 1.80s 26.71% runtime.pcvalue
0.73s 10.83% 22.85% 0.78s 11.57% runtime.unlock2
0.66s 9.79% 32.64% 0.67s 9.94% runtime.lock2
0.49s 7.27% 39.91% 0.55s 8.16% runtime.cgocall
0.48s 7.12% 47.03% 0.63s 9.35% runtime.step
0.25s 3.71% 50.74% 0.25s 3.71% [libart.so]
0.25s 3.71% 54.45% 0.25s 3.71% internal/bytealg.IndexByteString
0.24s 3.56% 58.01% 0.65s 9.64% runtime.gwrite
0.19s 2.82% 60.83% 0.19s 2.82% runtime.(*moduledata).textAddr
0.19s 2.82% 63.65% 0.40s 5.93% runtime.recordForPanic
0.15s 2.23% 65.88% 0.15s 2.23% runtime.readvarint (inline)
0.14s 2.08% 67.95% 0.33s 4.90% runtime.funcInfo.entry (inline)
0.14s 2.08% 70.03% 0.82s 12.17% runtime.printlock
0.12s 1.78% 71.81% 0.12s 1.78% runtime.memmove
0.09s 1.34% 73.15% 0.27s 4.01% runtime.printhex
0.08s 1.19% 74.33% 0.09s 1.34% runtime.findfunc
0.08s 1.19% 75.52% 0.27s 4.01% runtime.findnull
0.06s 0.89% 76.41% 4.27s 63.35% runtime.traceback2
0.05s 0.74% 77.15% 0.05s 0.74% runtime.acquirem (inline)
0.05s 0.74% 77.89% 1.05s 15.58% runtime.printArgs
0.05s 0.74% 78.64% 0.84s 12.46% runtime.printunlock (partial-inline)
0.04s 0.59% 79.23% 0.04s 0.59% internal/runtime/syscall.Syscall6
0.04s 0.59% 79.82% 0.52s 7.72% runtime.(*Frames).Next
0.04s 0.59% 80.42% 0.13s 1.93% runtime.printuintMaybe it's worth to mention that I get over 30000 errors like this:
02-21 16:18:00.578 28571 9175 I Fyne : From: fyne.io/fyne/v2@v2.7.2/internal/widget/base.go:120
02-21 16:18:00.578 28571 9175 I Fyne : *** Error in Fyne call thread, this should have been called in fyne.Do[AndWait] ***
Related issue: #5664.