Add TROUBLESHOOTING.md

[kickster97]

WHAT is this pull request doing?

This markdown guides users through their troubleshooting process, and aims to help them solve problems with their lavinmq instances, or provide important details in bug reports.

kind of Fixes #1446

HOW can this pull request be tested?

preview as markdown

[claude]

Claude finished @kickster97's task —— View job

---

Code Review - TROUBLESHOOTING.md

Todo List:

• Read and analyze TROUBLESHOOTING.md file
• Identify bugs, security vulnerabilities, performance issues, missing error handling, and Crystal anti-patterns
• Report findings

Issues Found

Security Vulnerabilities

1. Hardcoded default credentials (line 421):

   curl -u guest:guest http://localhost:15672/api/cluster

   Using default credentials in documentation examples can lead to security issues if users copy these commands without changing credentials.

Bugs

2. Incorrect ulimit usage (line 225):

   ulimit -c unlimited

   The ulimit command only affects the current shell session. If running LavinMQ as a systemd service, this won't have any effect on the service process.

3. Potential command failure (line 339):

   find /var/lib/lavinmq -name "msgs.*" -exec ls -l {} \; | sort -k5 -n | tail -20

   The sort -k5 -n won't work correctly with human-readable file sizes from ls -l. Should use ls -l and sort numerically on the size field.

4. macOS core dump location assumption (line 296):

   # When it crashes, the core dump will be in /cores/

   Modern macOS versions don't automatically create core dumps in /cores/ by default unless explicitly configured.

Performance Issues

5. Inefficient file listing command (line 336):

   du -sh /var/lib/lavinmq/*/* | sort -h | tail -20

   This command can be very slow on systems with many small files. A more efficient approach would be to use find with size parameters.

---

[carlhoerberg]

In general, use long command line option names eg --pid instead of just -p