Finding hot functions

Opening the Hotspots Browser

Select a Hotspot Detection Activity in the Performance Explorer view. Right click the Activity and select Open Hotspots.

This will open the Hotspots Browser. (Double clicking the Activity also has the same effect.)

The Process Hierarchy Tree

The left pane of the Hotspots Browser shows the Process Hierarchy Tree. This tree shows all of the processes that were sampled during the performance run.

Processes that correspond to the application being profiled are isolated under the My Application node. All other processes running on the system at the same time as the application show up under the Other Processes node.

Expand the My Application node to drill down and examine the processes, threads and modules that make up the application.

The percentages listed next to each node represent the amount of time the node takes from its parent node.

To save screen space, you can hide the tree panel and navigate the hierarchy using the breadcrumb bar. The breadcrumb bar is turned on/off by the toolbar button .

The Function Hotspots Table

Select a node in the Process Hierarchy Tree to see the functions that were sampled in that level of the hierarchy. By default the functions are sorted by the amount of time each function takes from the profile. The hottest functions are at the top of the list and make a good starting point for performance tuning.

When profiling Java / JNI, the function table includes methods from the JVM as well as your JNI code, and may contain methods compiled by the JIT at runtime. JNI functions will be shown with their names in the Java method style rather than the "mangled" JNI names used in your native code. JIT-compiled methods will be shown if the program was run with Java profiling enabled as described in Creating a Hotspot Detection Activity, otherwise JIT-compiled methods may be shown as NoSymbol on AIX or anon (...) on Linux.

For COBOL programs, the function table will include your COBOL procedures as well as functions from the COBOL runtime.

The filter box above the table can be used to filter the contents of the table. As you type into the box the contents of the table are filtered and the part of each function name that matches the filter is highlighted. Two wildcards are accepted: '*' matches any sequence of characters and '?' matches a single character. Click the eraser icon in the filter box to clear the filter.

To view the source code for a function, right click it and select Open Source. (Double clicking the function has the same effect.) This may be required when analyzing COBOL programs. COBOL procedures tend to be large and the Hotspots Browser may not provide enough detail. The Performance Source Viewer and Outline View can give detailed information by line and paragraph.

To see the sampled call stack for the function, right click it and select Show Callers/Callees.


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