Debugging LND

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:
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⛰ lnd --debuglevel=debug
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You may also specify logging per-subsystem, like this:
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⛰ lnd --debuglevel=<subsystem>=<level>,<subsystem2>=<level>,...
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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.
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⛰ lnd --profile=9736
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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:
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⛰ curl http://localhost:9736/debug/pprof/goroutine?debug=1
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...
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Last modified 4mo ago