Friday, June 15, 2018

The Unified Log in macOS Mojave: Signposts and Instruments

Howard Oakley:

Mojave is set to offer no respite or solution for the system administrator or advanced user. Console and the log command may have gained a few tweaks, but there are no signs of their being any more capable. However, Apple is introducing new features which should be very helpful to developers, particularly when optimising and tuning their products. As with WWDC 2018 as a whole, Mojave’s log is now about ‘doubling down’ on performance.


Signposts can have ‘metadata’ attached, which are roughly comparable to the contents of a normal eventMessage in os_log. Signposts additionally support an .event type as well as .begin and .end.

Points of Interest allow the developer to track where in the app a user is at a given moment, using the category .pointsOfInterest.


Apple has not stated how Signposts work with respect to the unified log.

See also: Measuring Performance Using Logging.

Previously: macOS 10.12.4 Locks Console Log Away From Normal Users, Sierra Logging Spew.

2 Comments RSS · Twitter


I didn't get the time to watch the WWDC video yet, but I did found that the new signpost API don't come without a price: they killed the old custom dtrace probe support in Instrument.

"Custom dtrace-based instrumentation that was available for macOS and Simulator only is no longer supported in Instruments. The new Custom Instruments packages based on os_signpost allow for greater flexibility and control over presentation of data and support all platforms"

I will have to update my probe and instruments configurations …

"Console and the log command may have gained a few tweaks"

Fixing to make it usable would be a higher priority than adding metadata.

Leave a Comment