1851566 - Stop exporting large data set from the parser worker for inline previews

Status: RESOLVED FIXED

(DevTools :: Debugger, task)

Description

[Alexandre Poirot [:ochameau]]

Based on bug 1843454 comment 1 investigations, we are currently sending very large arrays from the parser worker thread to the main thread.
The largest arrays are actually only used by inline preview to implement findBestMatchExpression:
https://searchfox.org/mozilla-central/rev/a7e33b7f61e7729e2b1051d2a7a27799f11a5de6/devtools/client/debugger/src/utils/ast.js#5-28
Instead, we could keep the data stored within the worker thread and lazily call a method on-demand in the worker thread.
We would still have to parse the whole file and still craft these large arrays, but drastically reduce GC overhead and CPU consumption solely related to data passing between threads.

Comment 1

[Alexandre Poirot [:ochameau]]

Attachment: Bug 1851566 - [devtools] Avoid passing large dataset out of the parser worker.

These three attributes are very large arrays and we could easily keep them
within the worker thread by exposing new dedicated method.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2ea4fd5d517a
[devtools] Avoid passing large dataset out of the parser worker. r=devtools-reviewers,bomsy

Comment 3

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/2ea4fd5d517a

Comment 4

[Nicolas Chevobbe [:nchevobbe]]

This might have caused a perf alert: https://treeherder.mozilla.org/perfherder/alerts?id=39518&hideDwnToInv=0