1. Design

The acquisition system consists of following four parts.

Metrics：Provide tools for collecting metric in different scenarios, including Counter, Gauge, Histogram, Timer and Rate, each with tags.
MetricManager
1. Provide functions such as create, query, update and remove metrics.
2. Provide its own start and stop methods.
CompositeReporter
1. Provide management of reporter.
2. Provide metric value to other systems, such as Jmx, Prometheus, IoTDB, etc.
3. Provide its own start and stop methods.
MetricService
1. Provide the start and stop method of metric service.
2. Provide the ability to reload properties when running.
3. Provide the ability to load predefined metric sets.
4. Provide the access of metricManager and CompositeReporter.

2. Test Report

We implemented the monitoring framework using Dropwizard and Micrometer respectively, and tested the results as follows:

2.1. Test Environment

Processor：Inter(R) Core(TM) i7-1065G7 CPU
RAM: 32G

2.2. Test Metrics

We use a single thread to create counter and run the test cases separately in two frameworks of Micrometer and Dropwizard. The test metrics as follows:
1. memory : Memory usage in MB.
2. create : The time required to create, in ms.
3. searchInorder : The time required for the sequential query, in ms.
4. searchDisorder : The time required for random queries in ms.

2.3. Test parameters

metric : test metric
name : The name of the test metric, unify to one length.
tag : The tag of the test metric, unify to one length.
metricNumberTotal：The number of metrics tested.
tagSingleNumber：Number of tags of the test metric.
tagTotalNumber：The number of tag pools, the default is 1000, all
tags are taken out of the tag pool.
searchNumber：The number of queries, the default is 1000000.
loop：The number of query loops, the default is 10.

2.4. Test Result

3. How to use?

3.1. Configuration

firstly, you need to set up some system property, for example:

System.setProperty("line.separator", "\n");
System.setProperty("IOTDB_CONF", "metrics/dropwizard-metrics/src/test/resources");

Then, you can modify iotdb-metric.yml as you like, some details:

properties	meaning	example
enableMetric	whether enable the module	true
enablePerformanceStat	Is stat performance of operation latency	true
metricReporterList	the list of reporter	JMX, PROMETHEUS, IOTDB
monitorType	The type of metric manager	DROPWIZARD, MICROMETER
metricLevel	the init level of metrics	ALL, NORMAL, IMPORTANT, CORE
predefinedMetrics	predefined set of metrics	JVM, LOGBACK, FILE, PROCESS, SYSTEM
asyncCollectPeriodInSecond	The period of the collection of some metrics in asynchronous way, such as tsfile size.	5
pushPeriodInSecond	the period time of push(used for prometheus, unit: s)	5

3.2. Use Guide in IoTDB Server Module

Now, MetricService is registered as IService in server and confignode module, you can simple set properties: enableMetric: true to use metric service.
In server module you can easily use these metric by MetricService.getInstance(), for example:

MetricService.getInstance().count(1, "operation_count", MetricLevel.IMPORTANT, "name", operation.getName());

4. How to implement your own metric framework?

implement your MetricService
1. You need to implement enablePredefinedMetrics to load predefined metrics.
2. You need to implement reloadProperties to reload properties when running.
implement your MetricManager
1. The name of MetricManager should start with monitorType, MetricService will init manager according to the prefix of class name.
2. You need to create src/main/resources/META-INF/services/org.apache.iotdb.metrics.AbstractMetricManager，and record your MetricManager class name in this file, such as org.apache.iotdb.metrics.dropwizard.DropwizardMetricManager
implement your reporter
1. You need to implement jmx reporter and prometheus reporter, notice that your jmx bean name should be unified as org.apache.iotdb.metrics
2. The name of your reporter should also start with monitorType
3. You need to create src/main/resources/META-INF/services/org.apache.iotdb.metrics.Reporter，and record your MetricManager class name in this file, such as org.apache.iotdb.metrics.dropwizard.reporter.DropwizardPrometheusReporter
implement your specific metric
1. They are counter, gauge, histogram, histogramSnapshot, rate and timer.
2. These metrics will be managed by your MetricManager, and reported by your reporter.
extends preDefinedMetric module:
1. you can add value into metrics/interface/src/main/java/org/apache/iotdb/metrics/utils/PredefinedMetric, such as System and Thread.
2. then you need to fix the implementation of enablePredefinedMetric(PredefinedMetric metric) in your manager.

5. Some docs

Metric Tool
Metric Tool(zh)