Stop Hook Exit Hang - Troubleshooting¶

Problem: amplihack hangs for 10-13 seconds on exit, blocking sys.stdin.read() during cleanup.

Status: ✅ Fixed in v0.9.1

Quick Fix (If Running Old Version)¶

# Upgrade to v0.9.1 or later
pip install --upgrade amplihack

# Or force kill if already hung
Ctrl+C (may need to press multiple times)
pkill -9 amplihack

Symptoms¶

Before Fix (v0.9.0 and earlier):

• Exit takes 10-13 seconds instead of <3 seconds
• No visible output during hang
• Process appears frozen
• Pressing Ctrl+C eventually works but feels unresponsive

After Fix (v0.9.1+):

• Exit completes in <3 seconds
• Clean shutdown behavior
• No hanging or blocking

Root Cause¶

The stop hook (power_steering.stop) was calling read_input() during atexit cleanup, which blocked on sys.stdin.read(). During shutdown:

1. Python's atexit handlers run
2. Stop hook calls read_input()
3. read_input() blocks on sys.stdin.read()
4. stdin is closed/detached during shutdown
5. Read operation hangs until timeout (10-13 seconds)

The Fix¶

Added centralized shutdown detection that:

1. Checks AMPLIHACK_SHUTDOWN_IN_PROGRESS environment variable
2. Skips stdin reads during shutdown
3. Returns safe defaults immediately
4. Completes cleanup in <3 seconds

See Shutdown Detection Explanation for technical details.

Verifying the Fix¶

# Check your version
amplihack --version

# Should be v0.9.1 or later for the fix

# Test exit behavior
amplihack
# ... do some work ...
# Type 'exit' or Ctrl+D

# Should exit cleanly in <3 seconds

If Still Experiencing Issues¶

Issue: Hangs persist after upgrade¶

Check:

# Verify you're running the new version
python -c "import amplihack; print(amplihack.__version__)"
# Should show 0.9.1 or later

Solution: Clear any cached installations

pip uninstall amplihack
pip cache purge
pip install amplihack

Issue: Environment variable not being set¶

Check:

# During normal operation, this should be unset
echo $AMPLIHACK_SHUTDOWN_IN_PROGRESS
# (should be empty)

# If it's set to "1", that's blocking normal operations
unset AMPLIHACK_SHUTDOWN_IN_PROGRESS

Issue: Custom hooks experiencing similar hangs¶

If you've written custom hooks that read stdin, see How to Add Shutdown Detection to Custom Hooks.

Related Issues¶

• GitHub Issue #1896: Stop hook exit hang
• Power Steering Troubleshooting

Need More Help?¶

1. Check Shutdown Detection Reference for API details
2. Review DISCOVERIES.md for known issues
3. Report a bug if the issue persists