[webkit-help] Memory useage inconsistent on iPhone between device log and Activity Monitor

tenghu guo guotenghu at gmail.com
Sat Sep 18 01:30:44 PDT 2021

I am debugging an app on an iOS device that renders an email using
WKWebview. The webview terminates for a given email so I want to find the
root case.

I got the device log from the Console app on my Mac. The log is saying that
the WebContent Process costs more than 1500MB memory so the system killed

default 08:34:32.855474+0800    kernel  EXC_RESOURCE ->
com.apple.WebKit.WebContent[9204] exceeded mem limit: ActiveSoft 1536
MB (non-fatal)

default 08:34:32.859688+0800    kernel  36050.843 memorystatus:
killing_highwater_process pid 9204 [com.apple.WebKit.WebContent]
(highwater 10) 1574608KB - memorystatus_available_pages: 46487

default 08:34:32.897449+0800    osanalyticshelper   Process
com.apple.WebKit.WebContent [9204] killed by jetsam reason highwater

But the Activity Monitor in Instrument tells me that the WebContent process
cost less than 200MB memory.
Which should I trust?

I also run the same app in an iOS simulator. The simulator won't crash
since there is a lot of memory for a Mac. The log says that the WebContent
process cost less than 200 MB memory as well.

default *15:22:03.064321*+0800 com.apple.WebKit.WebContent.Development
0x4493a3190 - PerformanceMonitor::measurePostLoadMemoryUsage: Process was
using 166961152 bytes of memory after the page load.

Why these reports not consistent?
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