Bugzilla

Olli asked for some data on the impact of this change in the code review so I am adding them here.

If you look at the [glam metrics](https://glam.telemetry.mozilla.org/fog/probe/timer_thread_timers_fired_per_wakeup/table?aggType=avg&currentPage=12&ping_type=*&visiblePercentiles=%5B99.9%2C99%2C95%2C75%2C50%2C25%2C5%5D) (switch to "Histogram Data" first) you can see an increase in the rate at which we fire 4, 3 and 2 timers per-wake-up, starting with the 2023-04-12:09 build when the first timer coalescing landed. It's about one percentage point increase on each but it is consistent and persistent. By my calculations we went from about 0.50 timers/wake-up to 0.55 as a result of these changes.

Another interesting thing that I noted while scrolling through the data is that, on some of the builds with fewer data points such as 2023-05-11:19, 2023-05-22:13, 2023-05-25:21 and 2023-05-29:8, there are even now instances in which we were able to coalesce many more timers together.

Olli asked for some data on the impact of this change in the code review so I am adding them here.

If you look at the [glam metrics](https://glam.telemetry.mozilla.org/fog/probe/timer_thread_timers_fired_per_wakeup/table?aggType=avg&currentPage=12&ping_type=*&visiblePercentiles=%5B99.9%2C99%2C95%2C75%2C50%2C25%2C5%5D) (switch to "Histogram Data" first) you can see an increase in the rate at which we fire 4, 3 and 2 timers per-wake-up, starting with the 2023-04-12:09 build when the first timer coalescing landed. It's about one percentage point increase on each but it is consistent and persistent. By my calculations we went from about 0.50 timers/wake-up to 0.55 as a result of these changes.

Another interesting thing that I noted while scrolling through the data is that, on some of the builds with fewer data points such as 2023-05-11:19, 2023-05-22:13, 2023-05-25:21 and 2023-05-29:8, there are even now instances in which we were able to coalesce many more timers together (probably long-running timers) which is pretty cool. I imagine that this is happening in the other builds too, but the rates are getting rounded down to 0%.