After creating the "shutdown" ping, we wait for (potentially long) saving operations to finish before collecting the "saved-session" payload. https://hg.mozilla.org/mozilla-central/annotate/2ddec2dedced/toolkit/components/telemetry/TelemetrySession.jsm#l1617 We should not wait on this before collecting the saved-session payload, instead kicking off both collections synchronously and afterwards waiting on both to be saved.

Comment on attachment 8637911 [details] [diff] [review] bug1186871.patch Review of attachment 8637911 [details] [diff] [review]: ----------------------------------------------------------------- r=me with the below fixed. ::: toolkit/components/telemetry/TelemetrySession.jsm @@ +1613,5 @@ > > /** > * Save both the "saved-session" and the "shutdown" pings to disk. > */ > saveShutdownPings: Task.async(function*() { This doesn't need to be a Task now. Just make it a plain function and |return Promise.all(...)|.

Thanks! Try push: https://treeherder.mozilla.org/#/jobs?repo=try&revision=f157d696aa5f

Comment on attachment 8637953 [details] [diff] [review] bug1186871.patch Approval Request Comment [Feature/regressing bug #]: This is part of the uplift3 batch for the unified Telemetry project: http://bit.ly/1TCl4r8 This is targetting 41 now and these are the last minor "feature" patches blocking shipping - any further patches will be fixes for data quality etc. with very limited scope & impact. [User impact if declined]: This affects data quality, potentially increasing data mismatch between "old" and "new" Telemetry data, which could potentially break data validation. [Describe test coverage new/current, TreeHerder]: This has good automated test-coverage. [Risks and why]: Low-risk, well understood change that just changes when ping data is generated. [String/UUID change made/needed]: No string changes.

Tracked for 41. Also requesting QE team to verify this fix along all Unified Telemetry fixes. Thanks!

Comment on attachment 8637953 [details] [diff] [review] bug1186871.patch Let's uplift to Aurora, has been in m-c for a few days now.

This appeared to have caused an xpcshell failure on at least Windows: https://treeherder.mozilla.org/logviewer.html#?job_id=996634&repo=mozilla-aurora Backed out in https://hg.mozilla.org/releases/mozilla-aurora/rev/047d1e5ffaa3

This updated patch fixes the problem for aurora.

Pushed to aurora. Treeherder: https://treeherder.mozilla.org/#/jobs?repo=mozilla-aurora&revision=a6899db62129 https://hg.mozilla.org/releases/mozilla-aurora/rev/a6899db62129

I don't think this bug needs separate QA attention.