Enforce foreground WebContent memory limit on macOS

[bnham]

f822d46

Enforce foreground WebContent memory limit on macOS
https://bugs.webkit.org/show_bug.cgi?id=240397

Reviewed by Chris Dumez.

We removed the foreground memory limit for WebContent on macOS in r272046. But based on some
bug reports that we've seen, it seems like we need to restore some limit to prevent bad user
outcomes when a misbehaving process has runaway memory usage.

This patch adds a foreground memory limit of 8GB or 16GB depending on RAM size. This matches
the limits set by other browsers for their content process.

* wtf/MemoryPressureHandler.cpp:
(WTF::thresholdForMemoryKillOfActiveProcess):
(WTF::MemoryPressureHandler::thresholdForMemoryKill):

Canonical link: https://commits.webkit.org/250548@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@294181 268f45cc-cd09-0410-ab3c-d52691b4dbfc

[cdumez]

Change log says:

This patch adds a foreground memory limit of 8GB or 16GB depending on RAM size

but seems like the code does something a bit different? Even if you assume there is a single tab in the process, seems like 16GB of RAM would give you a limit of 8GB, no? Since you are using > and not >= in your check.

[cdumez]

Oh, I misread. Your change log only says it's based on RAM size but no actual values.

[bnham]

Right, the > rather than >= here is intentional to match the magic values that other browsers chose based on RAM size.

[cdumez]

r=me

[webkit-early-warning-system]

Committed r294181 (250548@main): https://commits.webkit.org/250548@main

Reviewed commits have been landed. Closing PR #618 and removing active labels.