Overview

Users utilizing the M1 resource class on the CircleCI macOS executor are seeing builds hang. Though we can see builds hanging or timing out for other reasons, a specific bug in Apple's hypervisor framework that can cause issues in virtualized environments. These issues arise when a simulator is launched. You may notice a "Too long with no output (exceeded 5m0s): context deadline exceeded" error. 

Resolution 

We have significant improvements in performance when a simulator is booted for the second time by preforming the following steps: 

1. Launch your simulator at the beginning of your build. You may use the CircleCI macOS orb's preboot-simulator command.

2. Wait for your simulator to to be booted. You may use the CircleCI macOS orb. This orb includes a command; wait-until-simulator-booted. This command will wait until your simulator has booted or your job's `NO_OUTPUT_TIMEOUT` is hit. This is 10 minutes by default.

3. Shutdown the simulator: xcrun simctl shutdown $DEVICE_ID

4. repeat steps 1 & 2 

Other workarounds :

• Adding a retry to the step  in which you start your simulator to avoid having to re-run your build. 
• Add a final step that uses the when attribute when the value of "on_fail" and CircleCI v1 retry a build endpoint to rerun the job upon failure. 

Additional resources: 

• Discuss thread: Severe performance problems with Xcode 15
• MacOS Execution environment