1780330 - Change PContent's ShutdownProfile IPC to pass a shmem and pid

Status: NEW

(Core :: Gecko Profiler, task, P3)

Description

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

The current ShutdownProfile IPC passes the shutdown profile by string.
Because of the IPC message limit of 256MB, some big child-process profiles could be discarded.
For comparison, PProfiler's GatherProfile uses a shmem, which allows bigger profiles -- still effectively limited to 1GB, to fit in a JS string.

So to remove this IPC limitation, ShutdownProfile should be modified to pass a shmem.
And while modifying it, we should also pass the source pid (process id), which will be useful to identify that sub-profile if needed.

Comment 1

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

Note: Bug 1779367 changed ProfilerChild::GrabShutdownProfile to catch profiles that would be over the IPC message limit, it should also be changed to the higher JS string limit.