Commits on Jun 28, 2018

1. deps: V8: backport b49206d from upstream …

   This is the v8.x backport of nodejs#20727.
   
   Original commit message:
     ThreadDataTable: Change global linked list to per-Isolate hash map.
   
     For use cases with a large number of threads or a large number of
     isolates (or both), ThreadDataTable can be a major performance
     bottleneck due to O(n) lookup time of the linked list. Switching to a
     hash map reduces this to O(1).
   
     Example 1: Sandstorm.io, a Node.js app that utilizes "fibers", was
     observed spending the majority of CPU time iterating over the
     ThreadDataTable.
     See: https://sandstorm.io/news/2016-09-30-fiber-bomb-debugging-story
   
     Example 2: Cloudflare's Workers engine, a high-multi-tenancy web
     server framework built on V8 (but not Node), creates large numbers of
     threads and isolates per-process. It saw a 34x improvement in
     throughput when we applied this patch.
   
     Cloudflare has been using a patch in production since the Worker
     launch which replaces the linked list with a hash map -- but still
     global.
   
     This commit builds on that but goes further and creates a separate
     hash map and mutex for each isolate, with the table being a member of
     the Isolate class. This avoids any globals and should reduce lock
     contention.
   
     Bug: v8:5338
     Change-Id: If0d11509afb2e043b888c376e36d3463db931b47
     Reviewed-on: https://chromium-review.googlesource.com/1014407
     Reviewed-by: Yang Guo <yangguo@chromium.org>
     Commit-Queue: Yang Guo <yangguo@chromium.org>
     Cr-Commit-Position: refs/heads/master@{nodejs#52753}
   
   Backport-PR-URL: nodejs#21529
   PR-URL: nodejs#20727
   Refs: nodejs#20083
   Refs: nodejs#20083
   Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
   Reviewed-By: James M Snell <jasnell@gmail.com>

   

   ofrobots committed Jun 28, 2018
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