Taking a peek into deepest macOS: DispatchView first beta

With more apps and services using Grand Central Dispatch (GCD), it has become much tougher to diagnose their problems. When Time Machine stops making regular backups, looking in the log for error messages from Time Machine is futile. This is because the failure is not in any of its components, but in the systems which make up GCD.

You can use Consolation, my free log browser from the Downloads item above, or Apple’s Console, or even the log command in Terminal. But none of these is straightforward: you have to understand what you are doing and how best to look for the underlying problems.

DispatchView is a new, free app which uses code from Consolation to look at the two major components of GCD: the Duet Activity Scheduler (DAS), and Centralized Task Scheduling (CTS). It is very simple to use, with just three controls, and in future versions will analyse log content for those two systems to inform you of their activity and health. In this first beta, it displays their log entries so that you can trace faults and problems with task dispatch.

When you have selected the period of interest, such as the last ten minutes, click on its single button to fetch log entries for those two systems for that period. They will then be displayed in the two lower panes – those for GCD at the left, and for CTS at the right.


The two panes scroll independently, so that you can identify a precise time of interest, say, in the CTS entries (which are more explicit), then scroll the entries on the left to bring them into synchrony. You can trace activity in DAS which corresponds to that in CTS, for example to identify a failure to run Time Machine’s backup activity on time.

If you want to explore what DAS and CTS are up to, this is currently the only convenient way of doing so.

I hope that it is useful and informative.

The latest release is available from Downloads above.