message: Add DEBUG_LOCKCONTENTION documentation to the developer notes
  Github-Pull:
  Rebassedd-From:
diff: @@ -17,6 +17,7 @@ Developer Notes
  - [`debug.log`](#debuglog)
  - [Signet, testnet, and regtest modes](#signet-testnet-and-regtest-modes)
  - [DEBUG_LOCKORDER](#debug_lockorder)
  + - [DEBUG_LOCKCONTENTION](#debug_lockcontention)
  - [Valgrind suppressions file](#valgrind-suppressions-file)
  - [Compiling for test coverage](#compiling-for-test-coverage)
  - [Performance profiling with perf](#performance-profiling-with-perf)
  @@ -315,6 +316,19 @@ configure option adds `-DDEBUG_LOCKORDER` to the compiler flags. This inserts
  run-time checks to keep track of which locks are held and adds warnings to the
  `debug.log` file if inconsistencies are detected.
  +### DEBUG_LOCKCONTENTION
  +
  +Defining `DEBUG_LOCKCONTENTION` adds a "lock" logging category to the logging
  +RPC that, when enabled, logs the location and duration of each lock contention
  +to the `debug.log` file.
  +
  +To enable it, run configure with `-DDEBUG_LOCKCONTENTION` added to your
  +CPPFLAGS, e.g. `CPPFLAGS="-DDEBUG_LOCKCONTENTION"`, then build and run bitcoind.
  +
  +You can then use the `-debug=lock` configuration option at bitcoind startup or
  +`bitcoin-cli logging '["lock"]'` at runtime to turn on lock contention logging.
  +It can be toggled off again with `bitcoin-cli logging [] '["lock"]'`.
  +
  ### Assertions and Checks
  The util file `src/util/check.h` offers helpers to protect against coding and
  