microsoft/Terminal

Rapid background palette changes can make Windows Terminal hang

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#17,734 opened on Aug 17, 2024

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Area-VTHelp WantedIssue-BugProduct-Terminal

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Description

Windows Terminal version

1.21.1772.0

Windows build number

10.0.19045.4780

Other Software

No response

Steps to reproduce

Run the following python script:

import sys

for j in range(21845):
  i = j*3 
  r,g,b = i,i+1,i+2
  seq = '\033]11;rgb:%04x/%04X/%04x\033\\' % (r,g,b)
  sys.stdout.write(seq)
  sys.stdout.flush()

sys.stdout.write('\033]11;rgb:00/00/00\033\\')

Expected Behavior

The background color should fade from black to white, then reset to black and exit. The terminal should still work at that point.

Actual Behavior

The background fade works, but the terminal become unusable once the script has finished. None of the tabs work, and the title bar eventually shows "(Not Responding)".

I briefly looked at this in the debugger, and it appeared that it was triggering some sort of theme update event whenever the background changed, and I suspect it may have just got overloaded with a backlog of those events.

Contributor guide

Research direction
Investigate the handling of OSC 11 sequences in the terminal renderer. Look for theme update event propagation and see if there is a lack of throttling or if the event queue gets overwhelmed. Check the code in TerminalCore or renderer that processes these color changes and trace how they trigger UI updates.
Tech stack
cpp
Domain
desktop
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitC++Debugging skills
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60