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Overview
lnd ships with a few useful features for debugging, such as a built-in
profiler and tunable logging levels. If you need to submit a bug report
for lnd, it may be helpful to capture debug logging and performance
data ahead of time.
Debug Logging
You can enable debug logging in lnd by passing the --debuglevel flag. For
example, to increase the log level from info to debug:
⛰ lnd --debuglevel=debug
You may also specify logging per-subsystem, like this:
⛰ lnd --debuglevel=<subsystem>=<level>,<subsystem2>=<level>,...
Capturing pprof data with lnd
lnd has a built-in feature which allows you to capture profiling data at
runtime using pprof, a profiler for
Go. The profiler has negligible performance overhead during normal operations
(unless you have explicitly enabled CPU profiling).
To enable this ability, start lnd with the --profile option using a free port.
⛰ lnd --profile=9736
Now, with lnd running, you can use the pprof endpoint on port 9736 to collect
runtime profiling data. You can fetch this data using curl like so:
⛰ curl http://localhost:9736/debug/pprof/goroutine?debug=1
...