mac-samples/StartupTiming

Startup Timing

One important metric of application performance is the time it takes to start up. Measuring that accurately can be a challenge, especially in the world of managed code, where a significant amount of work is done before your managed entry point is invoked.

This sample uses the custom initialization feature in Xamarin.Mac to have a C function invoked very early in the startup process. That function in our case just prints the current number of milliseconds via gettimeofday.

We can then compare that to a call to DateTimeOffset.Now.ToUnixTimeMilliseconds inside AppDelegate.DidFinishLaunching and have a very reasonable idea how long our startup took.

There will be a portion not measured here, as the creation of a process through the custom initialization method is not measure, but for a vast majority of applications this is neglectable.

The application can be launched from the command line via bin/Debug/StartupTiming.app/Contents/MacOS/StartupTiming to easily test timing repeatedly.

Technical Notes

• This application linked to the static library native/time.a which is native/time.c compiled via clang -c time.c -o time.o && libtool -static time.o -o time.a.
• --link_flags="-force_load native/time.a" needs to be passed as an additional mmp argument to prevent the native linker from stripping xamarin_app_initialize from your final binary.