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new 79d5649 HBASE-22700 (addendum): Clarify ZK session timeout doc (#1748)
79d5649 is described below
commit 79d56499ca363d195d67b789ee7fb501bcb0786e
Author: Bharath Vissapragada <bhara...@apache.org>
AuthorDate: Wed May 27 10:52:03 2020 -0700
HBASE-22700 (addendum): Clarify ZK session timeout doc (#1748)
The current wording gives an impression the session timeout range
on the ZK side is forced to be in the range [2 * tickTime, 20 * tickTime].
This range is configurable on the ZK service side using minSessionTimeout
and maxSessionTimeout. Clarified that.
Signed-off-by: Jan Hentschel <j...@apache.org
Signed-off-by: Andrew Purtell <apurt...@apache.org>
---
src/main/asciidoc/_chapters/schema_design.adoc | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/main/asciidoc/_chapters/schema_design.adoc
b/src/main/asciidoc/_chapters/schema_design.adoc
index 98094bf..2f98e3a 100644
--- a/src/main/asciidoc/_chapters/schema_design.adoc
+++ b/src/main/asciidoc/_chapters/schema_design.adoc
@@ -1142,7 +1142,11 @@ Disable Nagle’s algorithm. Delayed ACKs can add up to
~200ms to RPC round trip
Detect regionserver failure as fast as reasonable. Set the following
parameters:
* In `hbase-site.xml`, set `zookeeper.session.timeout` to 30 seconds or less
to bound failure detection (20-30 seconds is a good start).
-- Notice: the `sessionTimeout` of zookeeper is limited between 2 times and 20
times the `tickTime`(the basic time unit in milliseconds used by ZooKeeper.the
default value is 2000ms.It is used to do heartbeats and the minimum session
timeout will be twice the tickTime).
+- Note: Zookeeper clients negotiate a session timeout with the server during
client init. Server enforces this timeout to be in the
+range [`minSessionTimeout`, `maxSessionTimeout`] and both these timeouts
(measured in milliseconds) are configurable in Zookeeper service configuration.
+If not configured, these default to 2 * `tickTime` and 20 * `tickTime`
respectively (`tickTime` is the basic time unit used by ZooKeeper,
+as measured in milliseconds. It is used to regulate heartbeats, timeouts
etc.). Refer to Zookeeper documentation for additional details.
+
* Detect and avoid unhealthy or failed HDFS DataNodes: in `hdfs-site.xml` and
`hbase-site.xml`, set the following parameters:
- `dfs.namenode.avoid.read.stale.datanode = true`
- `dfs.namenode.avoid.write.stale.datanode = true`
