Memory Metrics

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This is a legacy Apache Ignite documentation

The new documentation is hosted here: https://ignite.apache.org/docs/latest/

Data Region Metrics

Ignite durable memory can be monitored via several parameters exposed through the DataRegionMetrics interface, as well as JMX bean. Having access to the data region metrics can help track overall memory utilization, measure its performance, and execute required optimizations.

The DataRegionMetrics interface is the main entry point that provides memory-related metrics of a specific Ignite node. Since there can be several regions configured on a node, metrics for every region are collected and obtained individually.

Enabling Data Region Metrics

To enable data region metrics, set DataRegionConfiguration.setMetricsEnabled(true) for every region you want to collect the metrics for.

<bean class="org.apache.ignite.configuration.IgniteConfiguration">
  <property name="dataStorageConfiguration">
    <bean class="org.apache.ignite.configuration.DataStorageConfiguration">
      <property name="dataRegionConfigurations">
        <list>
          <bean class="org.apache.ignite.configuration.DataRegionConfiguration">
            <!-- Custom region name. -->
            <property name="name" value="myDataRegion"/>

            <!-- Enable metrics for this data region  -->
            <property name="metricsEnabled" value="true"/>
            
            <!-- Other configurations -->
            ...
          </bean>
        </list>
      </property>
    </bean>
  </property>
  
  <!-- Other Ignite configurations -->
  ...
</bean>

// Ignite configuration.
IgniteConfiguration cfg = new IgniteConfiguration();

// Durable Memory configuration.
DataStorageConfiguration storageCfg = new DataStorageConfiguration();

// Create a new data region.
DataRegionConfiguration regionCfg = new DataRegionConfiguration();

// Region name.
regionCfg.setName("myDataRegion");

// Enabe metrics for this region.
regionCfg.setMetricsEnabled(true);

// Set the data region configuration.
storageCfg.setDataRegionConfigurations(regionCfg);

// Other configurations
...

// Apply the new configuration.
cfg.setDataStorageConfiguration(storageCfg);

Getting Metrics

Use Ignite.dataRegionMetrics() interface method or a respective JMX bean to get the latest metrics snapshot and iterate over it, as shown in the example below:

// Get the metrics of all the data regions configured on a node.
Collection<DataRegionMetrics> regionsMetrics = ignite.dataRegionMetrics();
            
// Print out some of the metrics.
for (DataRegionMetrics metrics : regionsMetrics) {
    System.out.println(">>> Memory Region Name: " + metrics.getName());
    System.out.println(">>> Allocation Rate: " + metrics.getAllocationRate());
    System.out.println(">>> Fill Factor: " + metrics.getPagesFillFactor());
    System.out.println(">>> Allocated Size: " + metrics.getTotalAllocatedPages());
    System.out.println(">>> Physical Memory Size: " + metrics.getPhysicalMemorySize());
}

Following is the list of metrics available for data region:

Using JMX Bean

All DataRegionMetrics of a local Apache Ignite node are visible through JMX interface - DataRegionMetricsMXBean. You can connect to the bean from any JMX-compliant tool or API.

Use the DataRegionMetricsMXBean.enableMetrics() method exposed by a special JMX bean to activate collecting of data region metrics.

The JMX beans expose the same set of metrics that DataRegionMetrics has, as well as a few additional ones. See DataRegionMetricsMXBean JavaDoc for more details.

Ignite Persistence Metrics

Ignite also provides a set of metrics for Ignite persistence when it's enabled for a specific data region covered above. These metrics are grouped under the DataStorageMetrics interface.
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Enabling Data Storage Metrics

To enable Ignite presistence metrics, set DataStorageConfiguration.setMetricsEnabled(true), like so:

<bean class="org.apache.ignite.configuration.IgniteConfiguration">
  <property name="dataStorageConfiguration">
    <bean class="org.apache.ignite.configuration.DataStorageConfiguration">
      <!-- Enable metrics for Ignite persistence  -->
      <property name="metricsEnabled" value="true"/>
      
      <!-- Other configurations -->
      ...
    </bean>
  </property>
  
  <!-- Other Ignite configurations -->
  ...
</bean>

// Ignite configuration.
IgniteConfiguration cfg = new IgniteConfiguration();

// Durable Memory configuration.
DataStorageConfiguration storageCfg = new DataStorageConfiguration();

// Enable metrics for Ignite persistence.
storageCfg.setMetricsEnabled(true);

// Other configurations
...

// Apply the new configuration.
cfg.setDataStorageConfiguration(storageCfg);

Getting Metrics

Call Ignite.dataStorageMetrics() method to get the latest persistence metrics snapshot, as shown in the example below:

// Getting metrics.
DataStorageMetrics pm = ignite.dataStorageMetrics();

System.out.println("Fsync duration: " + pm.getLastCheckpointFsyncDuration());

System.out.println("Data pages: " + pm.getLastCheckpointDataPagesNumber());

System.out.println("Checkpoint duration:" + pm.getLastCheckpointDuration());

Following are some of the available metrics for data storage:

For a complete list, see DataStorageMetrics JavaDoc.

Using JMX Bean

Ignite persistence metrics can also be collected through the JMX interface - DataStorageMetricsMXBean. You can connect to the bean from any JMX-compliant tool or API.

Use the DataStorageMetricsMXBean.enableMetrics() method exposed by a special JMX bean to activate collecting of Ignite persistence related metrics.

The JMX beans expose the same set of metrics that DataStorageMetrics has, as well as a few additional ones. See DataStorageMetricsMXBean JavaDocs for more details.

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Enabling Metrics Collection

Metrics collection is not a free operation and might affect the performance of an application. For this reason, the metrics is turned off by default.

To turn the metrics on, use one of the following approaches:

• Set DataRegionConfiguration.setMetricsEnabled(true) for every region you want to collect the metrics for.
• Set DataStorageConfiguration.setMetricsEnabled(true) to collect Ignite persistence metrics.
• Use the DataRegionMetricsMXBean.enableMetrics() method exposed by a special JMX bean.
• Use the DataStorageMetricsMXBean.enableMetrics() method exposed by a special JMX bean to activate collecting of Ignite persistence related metrics.

Memory Usage Calculation

You can also obtain metrics for caches associated with a particular CacheGroup. Currently, these metrics are available only through JMX interface - CacheGroupMetricsMXBean. Refer to CacheGroupMetricsMXBean JavaDoc for a complete list of metrics available.

Single Node Memory Usage

The following examples show how to calculate current node size - the total size of data on a node in MB/GB, and current cache size - the size of data in a cache in MB/GB.

1. Current node size is DataStorageMetricsMXBean#getTotalAllocatedSize

2. The current size of a specific cache on a node is CacheGroupMetricsMXBean#getTotalAllocatedSize. Note that there should be only one cache within a cache group (default behavior) to make use of the metric.

Cluster-Wide Memory Usage

1. To calculate the total cluster size, you can sum the DataStorageMetricsMXBean#getTotalAllocatedSize of all nodes.

2. Current cache size is the sum of CacheGroupMetricsMXBean#getTotalAllocatedSize of all nodes. Note that there should be only one cache within a cache group (default behavior) to make use of the metric.