kudu git commit: docs: add 1.5.0 release note for thread count reduction

[da...@apache.org]

Repository: kudu
Updated Branches:
  refs/heads/branch-1.5.x 30c98e578 -> 19725d1fe


docs: add 1.5.0 release note for thread count reduction

Change-Id: I06939f0e01db780f86a7da16e92e5acd188b6925
Reviewed-on: http://gerrit.cloudera.org:8080/7905
Reviewed-by: Jean-Daniel Cryans <jd...@apache.org>
Tested-by: Dan Burkert <da...@apache.org>
(cherry picked from commit 595af7cdfb6b5e3c2d8adcd74ffb97032bae4ff3)
Reviewed-on: http://gerrit.cloudera.org:8080/7906
Reviewed-by: Dan Burkert <da...@apache.org>


Project: http://git-wip-us.apache.org/repos/asf/kudu/repo
Commit: http://git-wip-us.apache.org/repos/asf/kudu/commit/19725d1f
Tree: http://git-wip-us.apache.org/repos/asf/kudu/tree/19725d1f
Diff: http://git-wip-us.apache.org/repos/asf/kudu/diff/19725d1f

Branch: refs/heads/branch-1.5.x
Commit: 19725d1fe4b3fe128628301b9716f259cb1006d0
Parents: 30c98e5
Author: Adar Dembo <ad...@cloudera.com>
Authored: Wed Aug 30 14:31:19 2017 -0700
Committer: Dan Burkert <da...@apache.org>
Committed: Wed Aug 30 22:24:43 2017 +0000

----------------------------------------------------------------------
 docs/release_notes.adoc | 11 +++++++++++
 1 file changed, 11 insertions(+)
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http://git-wip-us.apache.org/repos/asf/kudu/blob/19725d1f/docs/release_notes.adoc
----------------------------------------------------------------------
diff --git a/docs/release_notes.adoc b/docs/release_notes.adoc
index 626165f..77fb222 100644
--- a/docs/release_notes.adoc
+++ b/docs/release_notes.adoc
@@ -118,6 +118,17 @@
   significant depending on the workload (this will be resolved in a future
   release).
 
+* The number of threads used by the Kudu Tablet Server has been further reduced.
+  Previously, each follower tablet replica used a dedicated thread to detect
+  leader tablet replica failures, and each leader replica used one dedicated
+  thread per follower to send Raft heartbeats to that follower. The work
+  performed by these dedicated threads has been reassigned to other threads.
+  Other improvements were made to facilitate better thread sharing by tablets.
+  For the purpose of capacity planning, expect the Kudu Tablet Server to create
+  one thread for every five "cold" (i.e. those not servicing writes) tablets,
+  and an additional three threads for every "hot" tablet. This will be further
+  improved upon in future Kudu releases.
+
 [[rn_1.5.0_fixed_issues]]
 == Fixed Issues