116: Jittery Moment

Discussion: Time Profiler But first: a brief rundown of the Instruments UI Toolbar Record/Stop Pause Target Selection Status display Strategy Selection CPU data Instrument data Thread data Detail/inspector toggles Timeline Plots data along the time your app was sampled Can be filtered and zoomed Disclosure arrow can toggle display of just the current run or of all runs in the trace document Detail Contents vary by Instrument, but this will generally be a table with some representation of the sampled data Inspectors Record Settings Display Settings Extended detail (often the heaviest stack trace) What is Time Profiler? An Instrument providing sample-based analysis of an application’s activity Periodically samples the call stack to determine where an app is spending its time These are instantaneous samples. They don’t track the duration of a function call, but rather how many times when sampled was the application currently in said function call. No distinction between a fast function called many times and a slow function called few times Extremely fast functions may not get sampled at all, if they happen to occur in between samples Provides a detail view listing call trees, optionally separated by thread and/or state, allowing the developer to drive down into calls to identify areas that may need to be optimized Weight - Percentage of samples in which a function appeared and an aggregate summary of samples (count * sample interval) Self Weight - Aggregate summary of samples in which the function was at the top of the call stack Symbol Name - The thing represented in the current row (may be a function, method, closure/block, thread, or app) Category Additional columns available: Count Self Count Library Picks John SelfControl Darryl WWDC 2016 Session 418 - Using Time Profiler in Instruments Alternative show title suggestions Try harder n squared complexity my code, vs not my code expected or unexpected notion of runs