Matt Stump created CASSANDRA-9242:
-------------------------------------
Summary: Add PerfDisableSharedMem to default JVM params
Key: CASSANDRA-9242
URL: https://issues.apache.org/jira/browse/CASSANDRA-9242
Project: Cassandra
Issue Type: Improvement
Components: Config
Reporter: Matt Stump
We should add PerfDisableSharedMem to default JVM params. The JVM will save
stats to a memory mapped file when reaching a safepoint. This is performed
synchronously and the JVM remains paused while this action takes place.
Occasionally the OS will stall the calling thread while this happens resulting
in significant impact to worst case JVM pauses. By disabling the save in the
JVM these mysterious multi-second pauses disappear.
The behavior is outlined in [this
article|http://www.evanjones.ca/jvm-mmap-pause.html]. Another manifestation is
significant time spent in sys during GC pauses. In [the linked
test|http://cstar.datastax.com/graph?stats=762d9c2a-eace-11e4-8236-42010af0688f&metric=gc_max_ms&operation=1_write&smoothing=1&show_aggregates=true&xmin=0&xmax=110.77&ymin=0&ymax=10421.4]
you'll notice multiple seconds spent in sys during the longest pauses.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
