Telemetry View Section

  The telemetry view section shows historic graphs that display information about the profiled JVM. JProfiler shows a number of pre-defined system telemetries and in addition allows you to define custom telemetries.

The first view in the telemetry section is an overview that shows all available system and custom telemetries in compact rows on top of each other. With the row height slider you and adjust the density of the display and the filter at the top allows you to adjust the displayed telemetries by name. Clicking on the telemetry name in the overview will take you to a detailed telemetry view.

The system telemetries are:

  • Memory

    Shows the maximum heap size and the amount of used and free space in it. This view can be displayed as a line graph or area graph.

    The drop down list at the top offers all available memory pools. Please see the article on tuning garbage collection for more information on heap memory pools. In addition, there are several memory pools for non-heap data structures. The drop down list shows all available memory pools in a tree-like structure, so you can display the sum of all heap pools (the default selection) or the sum of all non-heap pools in the graph.

  • Recorded objects
    Shows the total number of objects on the heap, divided into arrays and non-arrays. This view can be displayed as a line graph or area graph. Note that this view only displays recorded objects and is unavailable if no objects have been recorded so far. Objects that have been recorded are tracked even after recording has been stopped.
  • Recorded throughput
    Shows how many objects are garbage collected and created. The plotted values are time rates, so the total numbers in a time interval are given by the area under the respective lines. Note that this view only displays recorded objects and is unavailable if no objects have been recorded so far. Objects that have been recorded are tracked even after recording has been stopped.
  • GC activity
    Shows the garbage collector activity in percent of the elapsed time. This view is only available when profiling with a Java 1.5+ JVM. The combo box at the top allows you to show the activity for specific GC types. Sun JVMs implement a "Copy" and a "MarkSweepCompact" that apply to different object generations.
  • Classes
    Shows the total number of classes loaded by the JVM, divided into CPU-profiled and non-CPU-profiled classes. This view can be displayed as a line graph or area graph.
  • Threads
    Shows the total number of alive threads in the JVM, divided into the different thread states. This view can be displayed as a line graph or area graph.
  • CPU load
    Shows the CPU load of the profiled process in percent of the elapsed time. This view is only available when profiling with a Java 1.5+ JVM.
  Telemetries whose measurements are summable can be shown as a line graph and as an area graph. To change the graph type, choose Line Graph or Area Graph from the context or view menu. The graph type is a persistent view setting separate for each view and is also accessible through the view settings dialog.

When a view is shown as an area graph, the line which shows the total value is given by the upper bound of the filled area while the single contributions are shown as stacked area segments.

  When you move the mouse across a telemetry view, the time at the position of the closest data point to the mouse cursor and the corresponding values on the vertical axis will be shown in a tool tip. The current value of each data line is always shown next to the corresponding legend entry.

Horizontal and vertical grid lines of the VM telemetry views can be configured in the view settings dialog.

  Please see the help on graphs with a time axis for help on common properties of graph views.
  Note that you can use a trigger and the "Start recording" and "Stop recording" actions to control VM telemetry recording for offline profiling.