Database Reference
In-Depth Information
Cassandra's JMX interface
Cassandra has a powerful JMX interface to monitor almost all of its aspects. JMX is a
standard part of Java
standard edition
(
SE
) 5.0 and onward. It provides a standard inter-
face to manage and monitor resources such as applications, devices, JVM settings, and ser-
vices. The way JMX technology manages and monitors a resource is called
Managed
Beans
(
MBeans
). JMX defines standard connectors that enable us to access JMX agents
remotely. With this introductory JMX knowledge, let's see what Cassandra offers us to con-
trol or monitor almost all of its aspects using JMX.
Note
This discussion is sufficient to get you to work with JMX in the context of Cassandra.
Learn more about it at
http://docs.oracle.com/javase/tutorial/jmx/TOC.html
.
Cassandra exposes JMX MBeans in different packages. These are as follows:
•
org.apache.cassandra.internal
: This package includes MBeans that
inform us about internal operations. Therefore, you can view the status of AntiEn-
tropy, FlushWriter, gossip, hinted handoff, response stage, migration and stream
stages, pending range calculation, and commit log archival. Other than getting in-
ternal status statistics, there is not much that can be done with these MBeans.
•
org.apache.cassandra.db
: This is probably the most interesting MBean
package. It includes vital metrics and actionable operational items. MBeans give
statistics and commands for database components such as cache management,
table, commit log, compaction control, hinted handoff management, storage ser-
vice (general ring statistics and operations), and storage proxy (client read/write
statistics).
•
org.apache.cassandra.net
: This package contains statistics on network
communication within the cluster. It has some interesting Mbeans, such as Fail-
ureDetector, gossip, internode messaging, and data stream status.
•
org.apache.cassandra.request
: One can view pending and completed
tasks at different stages. The stages listed under this package are mutation, read re-
pair, read, replicate on write, and read response.
Cassandra is designed around
Staged Event Driven Architecture
(
SEDA
). At
very high levels, it chunks a task into multiple stages, with each having its own
thread pool and event queue. To read more about SEDA, visit
ht-
