Special case: database is locked/busy
It may happen that the 'database is locked/busy' warning appears
when storing new sensor values.
This is not a problem. No data will be lost.
This is because the API is multithreaded, but the SQLite engine is not.
If there are too many write requests) at once,
the engine will temporarily lock that database for further writes.
The client removes the data from the send buffer only after it is
acknowledged. Until this happens, the data is always re-sent on the
next write.
If the data has been saved in the meantime, a warning 'UNIQUE constraint
failed: MxChartDBxxx.ts' is written to the log file. This message
may be useful for analysis.
The maximum number of repetitions can be defined in the constants.js file
(parameter buffer_max_rows, default: 20).
To avoid the 'database is locked/busy' events, you can