1443889 - Web Replay: Support web workers

Status: RESOLVED INVALID

(Core :: General, enhancement)

Description

[Brian Hackett [Laid off!]]

The following patches add support for web workers when using Web Replay.  Executions using workers can be recorded and replayed, but the debugger cannot yet be used to set breakpoints in worker code or otherwise observe their state.

Comment 1

[Brian Hackett [Laid off!]]

Attachment: Part 1 - Allow the trigger and weak pointer APIs to be used off the main thread.

The trigger and weak pointer APIs in web replay could not be used off the main thread.  This patch fixes that and tweaks the semantics of ExecuteTriggers to support its use on web worker threads.

Comment 2

[Brian Hackett [Laid off!]]

Attachment: Part 2 - Ignore scripts from web workers in the replay debugger.

Only consider scripts and other content from the JSRuntime on the main thread in the replay debugger, and do a little cleanup.

Comment 3

[Brian Hackett [Laid off!]]

Attachment: Part 3 - Increase stack size of threads spawned during record/replay.

Web workers need larger stacks than most other threads, and since with web replay we spawn all threads up front and give them a fixed stack size before content has tried to spawn them and indicate a stack size, this patch just increases the stack size for all spawned threads.

Comment 4

[Brian Hackett [Laid off!]]

Attachment: Part 4 - Execute record/replay triggers at the top of the event loop for all threads.

Since part 1 allows ExecuteTriggers to be called on any thread, this patch fixes the call to this in the nsThread event loop so that it is called on all such threads (including those for web workers).

Comment 5

[Brian Hackett [Laid off!]]

Attachment: Part 5 - Allow web workers to be used when recording or replaying.

Remove the restriction that web workers can't be used when recording/replaying.  This also makes a couple fixes to the worker code for web replay:

- Don't process callbacks during the JS interrupt callback.  This callback runs at non-deterministic points during replay so can't perform actions that interact with the recording at all.  This change might cause problems for workers that iloop, and might need a more robust/complicated alternative approach in the future.

- Use the record/replay trigger mechanism to perform cycle collections at deterministic points in execution.

Comment 6

[Brian Hackett [Laid off!]]

https://hg.mozilla.org/projects/ash/rev/d865512815e936a3313e4b846196a99178f809c7
https://hg.mozilla.org/projects/ash/rev/62e651110f591bf7023e5be8c0730a901dfb9225
https://hg.mozilla.org/projects/ash/rev/1525a52989f7cadc2e8d8373e161bc3409c6a061
https://hg.mozilla.org/projects/ash/rev/91af7e277433fbb302e1041c90d99591482cb7da
https://hg.mozilla.org/projects/ash/rev/70e30746eb6cb231cd61d56545c9641e1b0fe679

Comment 7

[Brian Hackett [Laid off!]]

Closing this bug, all the changes here will be reviewed in separate bugs dependent on bug 1422587.