1795821 - [meta] Enhance error propagation and/or UI feedback for failed child process launches

Status: NEW

(Core :: DOM: Content Processes, enhancement)

Description

[Jens Stutte [:jstutte]]

With bug 1165945 we added the SUBPROCESS_LAUNCH_FAILURE telemetry and console log messages for failed child process launches.

Looking at that telemetry, this happens still at a frequency that might deserve some attention. While one might assume that this happens most probably under conditions where any meaningful UI reaction (like opening new dialogs) might be as difficult as launching processes (like OOM, lack of system handles, very slow processing), we might be just missing some recoverable condition.

Things we might want to look at (non exhaustive):

• How reliable our telemetry is for beta (apparently there is a non proportional high number of Windows 7 failures), Nightly values look not too bad and we might want to interpolate those to release
• If we can find "Failed to launch <process type> subprocess" messages in treeherder logs in order to see if there are patterns
• If we can have other means of collecting data (like MOZ_DIAGNOSTIC_ASSERT) in order to learn more about the condition the affected machines were in
• Which errors are propagated under which conditions by the async promise chain we have here and if there are recoverable conditions we might be able to distinguish and handle better or at least to notify to the user