Monitoring Oracle HTTP Server

6-4 Oracle Fusion Middleware Performance and Tuning Guide

6.1.1.3 DMS Sensors

DMS sensors measure performance data and enable DMS to define and collect a set of metrics. Certain metrics are always included with a sensor and other metrics are optionally included with a sensor. DMS has three different kinds of sensors: ■ Section 6.1.1.3.1, DMS PhaseEvent Sensors ■ Section 6.1.1.3.2, DMS Event Sensors ■ Section 6.1.1.3.3, DMS State Sensors

6.1.1.3.1 DMS PhaseEvent Sensors A DMS PhaseEvent sensor measures the time spent

in a specific section of code that has a beginning and an end. Use a PhaseEvent sensor to track time in a method or in a block of code. DMS can calculate optional metrics associated with a PhaseEvent, including the average, maximum, and minimum time that is spent in the PhaseEvent sensor. Table 6–3 lists the metrics available with PhaseEvent sensors.

6.1.1.3.2 DMS Event Sensors A DMS event sensor counts system events. Use a DMS

event sensor to track system events that have a short duration, or where the duration of the event is not of interest but the occurrence of the event is of interest. Table 6–4 describes the metric that is associated with an event sensor. Table 6–3 DMS PhaseEvent Sensor Metrics Metric Description sensor_name .time Specifies the total time spent in the phase sensor_name. Default metric: time is a default PhaseEvent sensor metric. sensor_name .completed Specifies the number of times the phase sensor_name has completed since the process was started. Optional metric sensor_name .minTime Specifies the minimum time spent in the phase sensor_name, for all the times the sensor_name phase completed. Optional metric sensor_name .maxTime Specifies the maximum time spent in the phase sensor_name, for all the times the sensor_name phase completed. Optional metric sensor_name .avg Specifies the average time spent in the phase sensor_name, computed as the total timenumber of times the phase completed. Optional metric sensor_name .active Specifies the number of threads in the phase sensor_name, at the time the DMS statistics are gathered the value may change over time. Optional metric sensor_name .maxActive Specifies the maximum number of concurrent threads in the phase sensor_name, since the process started. Optional metric Oracle Dynamic Monitoring Service 6-5

6.1.1.3.3 DMS State Sensors A DMS state sensor tracks the value of Java primitives or

the content of a Java object. Supported types include integer, double, long, and object. Use a state sensor when you want to track system status information or when you need a metric that is not associated with an event. For example, use state sensors to track queue lengths, pool sizes, buffer sizes, or host names. You assign a precomputed value to a state sensor. Table 6–5 describes the state sensor metrics. State sensors support a default metric value, as well as optional metrics. The optional minValue and maxValue metrics only apply for state sensors if the state sensor represents a numeric Java primitive of type integer, double, or long.

6.1.1.3.4 Sensor Naming Conventions The following list describes DMS sensor naming

conventions: ■ Sensor names should be descriptive, but not redundant. Sensor names should not contain any part of the noun name hierarchy, or type, as this is redundant. ■ Sensor names should avoid containing the value for the individual metrics. ■ Where multiple words are required to describe a sensor, the first word should start with a lowercase letter, and the following words should start with uppercase letters. Example: computeSeries ■ In general, avoid using a character in a sensor name. However, there are cases where it makes sense to use a name that contains . If a is used in a noun or sensor name, then when you use the sensor in a string with DMS methods, you need to use an alternative delimiter, such as , or _, which does not appear anywhere in the path; this enables the to be properly understood as part of the noun or sensor name rather than as a delimiter. For example, a child noun can have a name such as: examplesjspnumnumguess.jsp Table 6–4 DMS Event Sensor Metrics Metric Description sensor_name .count Specifies the number of times the event has occurred since the process started, where sensor_name is the name of the Event sensor as specified in the DMS instrumentation API. Default: count is the default metric for an event sensor. No other metrics are available for an event sensor. Table 6–5 DMS State Sensor Metrics Metric Description sensor_name .value Specifies the metric value for sensor_name, using the type assigned when sensor_name is created. Default: value is the default State metric. sensor_name .count Specifies the number of times sensor_name is updated. Optional metric sensor_name .minValue Specifies the minimum value for sensor_name since startup. Optional metric sensor_name .maxValue Specifies the maximum value this sensor_name since startup. Optional metric