commit 5912b768395ab595274c932bd653f9e47a93ec1c
author Leszek Swirski <leszeks@chromium.org> Thu Aug 16 14:56:13 2018
committer Commit Bot <commit-bot@chromium.org> Thu Aug 16 14:56:13 2018
tree 7c88b322ced42debfecc3f751812a061ba3ecc6e
parent f85a6593faa4608b445f230ae8b035c2fd68ec8a

[v8] Re-post non-blocking ScriptStreamer tasks

Posted blocking ScriptStreamer tasks can end up in a queue, and have
their Resource complete loading before the task even starts. When this
happens, these tasks will no longer block on network input, but they
will still be posted to the blocking task runner, which does not spin up
new threads if the running task is not blocked. When there are a lot of
small functions posted for streaming, this results in a slightly
paradoxical starvation, where the blocking task runner is processing
lots of no-longer-blocking tasks all in one thread, as it has no reason
to spin up new threads.

To avoid this, if a streaming task isn't started before the resource
finishes loading, we can cancel this posted task, and instead post a new
non-blocking task to the non-blocking thread pool. This frees up the
blocking task runner to process only blocking tasks (and thus allows it
to spin up new threads for them).

Bug: chromium:865098
Bug: chromium:866868
Change-Id: Iceb282582781109ade233366d1009c3be50db3a5
Reviewed-on: https://chromium-review.googlesource.com/1174380
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583649}