[CP] [Stable] Please cherry pick 82520abfb1dd82b36e4a50371e71572b2bd95b73 and 84b38aee393d9afc5f2cc83b8a816230478d0646

[a-siva]

Commit(s) to merge

82520abfb1dd82b36e4a50371e71572b2bd95b73 and 84b38aee393d9afc5f2cc83b8a816230478d0646

Target

stable and beta

Prepared changelist for beta/stable

https://dart-review.googlesource.com/c/sdk/+/347760

Issue Description

The change fixes the following

• an issue that causes Flutter apps to freeze when breakpoints are added to multiple isolates at the same time
• an issue that causes Flutter apps to crash during hot reload

What is the fix

• Use safepoint-safe RwLock for breakpoint locations locks
• Ensure setting breakpoints is lock-safe

Why cherry-pick

Flutter app developers have encountered these scenarios effecting developer productivity.

Risk

low

Issue link(s)

https://github.com/dart-lang/sdk/issues/54650

Extra Info

No response

[mit-mit]

SGTM

[a-siva]

Closing this as a duplicate of https://github.com/dart-lang/sdk/issues/54699. Will carry over @mits comment to the other issue.