GWicke has uploaded a new change for review.

  https://gerrit.wikimedia.org/r/192760

Change subject: Increase the JVM tenuring threshold
......................................................................

Increase the JVM tenuring threshold

During heavy read load the promotion rate from the young generation is too
high for incremental CMS, which causes CMS to switch to slow stop-the world
collections that take multiple seconds. This is slow enough for other nodes to
consider the node dead.

This patch increases the number of young space collections an object needs to
survive before being promoted to the eden generation. This increases the cost
in young space collections slightly in exchange for a lower promotion rate,
which should reduce or eliminate long stop-the-world collections in the old
space.

See also:
http://aryanet.com/blog/cassandra-garbage-collector-tuning

Change-Id: I26c946e05e651ccd68c767ffba51d2ff9598d87b
---
M templates/cassandra-env.sh.erb
1 file changed, 1 insertion(+), 1 deletion(-)


  git pull ssh://gerrit.wikimedia.org:29418/operations/puppet/cassandra 
refs/changes/60/192760/1

diff --git a/templates/cassandra-env.sh.erb b/templates/cassandra-env.sh.erb
index 2fd9aa4..84c2450 100644
--- a/templates/cassandra-env.sh.erb
+++ b/templates/cassandra-env.sh.erb
@@ -218,7 +218,7 @@
 JVM_OPTS="$JVM_OPTS -XX:+UseConcMarkSweepGC"
 JVM_OPTS="$JVM_OPTS -XX:+CMSParallelRemarkEnabled"
 JVM_OPTS="$JVM_OPTS -XX:SurvivorRatio=8"
-JVM_OPTS="$JVM_OPTS -XX:MaxTenuringThreshold=1"
+JVM_OPTS="$JVM_OPTS -XX:MaxTenuringThreshold=20"
 JVM_OPTS="$JVM_OPTS -XX:CMSInitiatingOccupancyFraction=75"
 JVM_OPTS="$JVM_OPTS -XX:+UseCMSInitiatingOccupancyOnly"
 JVM_OPTS="$JVM_OPTS -XX:+UseTLAB"

-- 
To view, visit https://gerrit.wikimedia.org/r/192760
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I26c946e05e651ccd68c767ffba51d2ff9598d87b
Gerrit-PatchSet: 1
Gerrit-Project: operations/puppet/cassandra
Gerrit-Branch: master
Gerrit-Owner: GWicke <[email protected]>

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