diagnosticd(8) System Manager's Manual diagnosticd(8)

diagnosticdunified logging system diagnostic daemon

diagnosticd is part of the unified logging system. It helps serve live debugging information. For example, it manages and delivers data to Console.app and the log(1) utility's stream command.

{ process }
     `--- os_log ---> ... { logd } ...
               \
                `---> { diagnosticd } ---> { Console.app }
                                      `---> { log stream }

Note that, when Console.app or log stream are actively displaying ongoing system data, diagnosticd and os_log(3) calls require extra system resources (e.g., CPU) to serve this data live.

log(1), os_log(3), logd(8)

Logging | Apple Developer Documentation

August 30, 2018 Darwin