I've set up Xcode/Instruments so that I'm monitoring an iPhone 6s's memory usage altogether. I've got a specific com.apple.WebKit Process that I would like to see very finetuned information on - as precise as possible. This com.apple.WebKit process will eventually crash the Mobile Safari running on an iPhone 6s using iOS 10 - this WebKit process will not crash an iPhone SE running iOS 11 Beta - but that's just to say that "things will eventually get better".

It seems that 1Gb of memory is not enough to run the com.apple.WebKit process for this specific scripted embed.

So, I start Instruments running and I see peaks of 640mb or so of memory usage - but how could I record this memory usage in the finest possible detail, so that I can figure out what drives this over the edge?

  • You might be at the limit of what instruments can do, but before guessing, can you edit to describe precisely what trigger or counters you measure to make the 640 mb threshold?
    – bmike
    Sep 10, 2017 at 14:26
  • @bmike I was seeing it in the instruments app, showing that it would go to 700mb and 600mb and oscillate between those, until the mobile safari running on iOS10 would crash. So I'm just trying to figure out the overall usage of the app running on webkit, so that we can start optimizing.
    – esaruoho
    Sep 10, 2017 at 16:44
  • I would love a follow on question - new thread if you want to show exactly what you are measuring in Instruments. If you're using a standard template or a custom one it will either teach people how to do what you already know and perhaps let people show you a better setup to pick apart the memory within Instruments.
    – bmike
    Sep 10, 2017 at 16:52
  • @bmike ok! i'll try and do that based on what you wrote there below. I'll try and get to do it tomorrow!
    – esaruoho
    Sep 11, 2017 at 18:15

1 Answer 1


I would probably consider Instruments job done once you know mobile safari is allocating 640 MB of ram and move on to Safari web inspector. Setting it up is quite easy and since you have XCode and macOS safari, you have first party tools to debug your process while it runs in real time.

The activity viewer will right away focus your efforts based on whether you have excessive warnings and errors or simply are loading a lot of assets.

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