regenrek / debug-lldb
Install for your project team
Run this command in your project directory to install the skill for your entire team:
mkdir -p .claude/skills/debug-lldb && curl -L -o skill.zip "https://fastmcp.me/Skills/Download/2921" && unzip -o skill.zip -d .claude/skills/debug-lldb && rm skill.zipProject Skills
This skill will be saved in .claude/skills/debug-lldb/ and checked into git. All team members will have access to it automatically.
Important: Please verify the skill by reviewing its instructions before using it.
Capture and analyze thread backtraces with LLDB/GDB to debug hangs, deadlocks, UI freezes, IPC stalls, or high-CPU loops across any language or project. Use when an app becomes unresponsive, switching contexts stalls, or you need thread stacks to locate lock inversion or blocking calls.
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--- name: debug-lldb description: Capture and analyze thread backtraces with LLDB/GDB to debug hangs, deadlocks, UI freezes, IPC stalls, or high-CPU loops across any language or project. Use when an app becomes unresponsive, switching contexts stalls, or you need thread stacks to locate lock inversion or blocking calls. --- # Debug Lldb ## Overview Capture stack traces from a live process to explain stalls and freezes, then triage for deadlocks, blocking IPC, or tight loops. Prefer repeat sampling so the hang signature is obvious. ## Workflow ### 1) Identify the process - Use `ps`/`pgrep` to get the PID. - Prefer the foreground app PID (not the dev server). ### 2) Capture backtraces (fast path) - Use the bundled script: - `scripts/collect_stacks.sh --pid <pid> --out /tmp/hang --repeat 3 --sleep 0.5` - Or by name: `scripts/collect_stacks.sh --name "<process-substring>" --out /tmp/hang` - Run in a separate terminal if the current one is interactive with the hung app. ### 3) Capture backtraces (manual) - macOS (LLDB): - `lldb -p <pid> -o 'thread backtrace all' -o 'detach' -o 'quit' > /tmp/hang.txt 2>&1` - Linux (GDB): - `gdb -q -p <pid> -ex "thread apply all bt" -ex "detach" -ex "quit" > /tmp/hang.txt 2>&1` - Windows: - Use WinDbg or cdb to capture all-thread backtraces. ### 4) Triage the hang - Compare 3–5 samples taken 0.2–1s apart. - Use `references/triage.md` for quick pattern matching (deadlock vs busy loop vs blocking I/O). ### 5) Attach context - Include what action triggered the stall and the exact time window. - Add relevant app logs around the stall. ## Resources ### scripts/ - `scripts/collect_stacks.sh` - attach to a PID or process name and capture N stack dumps. ### references/ - `references/triage.md` - quick patterns for deadlocks, blocking IPC, and busy loops.