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https://issues.apache.org/jira/browse/CASSANDRA-20446?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Dmitry Konstantinov updated CASSANDRA-20446:
--------------------------------------------
Change Category: Performance
Complexity: Low Hanging Fruit
> Reduce level of duplication for properties in JMX ObjectName for metrics
> ------------------------------------------------------------------------
>
> Key: CASSANDRA-20446
> URL: https://issues.apache.org/jira/browse/CASSANDRA-20446
> Project: Apache Cassandra
> Issue Type: Improvement
> Components: Observability/JMX
> Reporter: Dmitry Konstantinov
> Priority: Normal
> Attachments: image-2025-03-17-18-14-01-628.png,
> image-2025-03-17-18-14-48-658.png
>
>
> Currently we construct javax.management.ObjectName when we publish our
> metrics via JMX by concatenating key/value pairs and providing the result to
> ObjectName constructor:
> org.apache.cassandra.metrics.CassandraMetricsRegistry.MetricName#MetricName(...)
> {code:java}
> public MetricName(String group, String type, String name, String scope)
> {
> this(group, type, name, scope, createMBeanName(group, type, name, scope));
> }
> private static String createMBeanName(String group, String type, String name,
> String scope)
> {
> final StringBuilder nameBuilder = new StringBuilder();
> nameBuilder.append(ObjectName.quote(group));
> nameBuilder.append(":type=");
> nameBuilder.append(ObjectName.quote(type));
> if (scope != null)
> {
> nameBuilder.append(",scope=");
> nameBuilder.append(ObjectName.quote(scope));
> }
> if (name.length() > 0)
> {
> nameBuilder.append(",name=");
> nameBuilder.append(ObjectName.quote(name));
> }
> return nameBuilder.toString();
> }
> {code}
> {code}
> public ObjectName getMBeanName()
> {
> String mname = mBeanName;
> if (mname == null)
> mname = getMetricName();
> try
> {
> return new ObjectName(mname);
> } catch (MalformedObjectNameException e)
> {
> try
> {
> return new ObjectName(ObjectName.quote(mname));
> } catch (MalformedObjectNameException e1)
> {
> throw new RuntimeException(e1);
> }
> }
> }
> {code}
> later javax.management.ObjectName parses and splits this concatenated name
> back to fill internal _propertyList map.
> As a result we get a lot of small duplicated property name/value String
> objects (like: "scope", "name", "<some metric name>", "<some table name>"
> stored within JMX repository.
> I have found this issue during an analysis of memory usage for a dev instance
> of Cassandra (4.1 + JDK 11) where we want to have memory usage to be small to
> reduce cost of dev envs.
> There are 275 tables for the instance (including all system ones), it has
> 395MiB heap used and about 52MiB from them are consumed by
> com.sun.jmx.mbeanserver.JmxMBeanServer, where about 41 MiB is spent for
> ObjectName objects (a big percent, and the second major contributor to memory
> usage after heap memtables):
> !image-2025-03-17-18-14-01-628.png|width=400!
> !image-2025-03-17-18-14-48-658.png|width=400!
> The possible way to reduce this _propertyList duplication is to use another
> constructor to build ObjectName: ObjectName(String domain, Hashtable<String,
> String> table) and provide the properties as a map within
> org.apache.cassandra.metrics.CassandraMetricsRegistry.MetricName#getMBeanName
> logic, in this way we can avoid the String duplicates in properties across
> the ObjectName instances.
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