Hot Spot Comparison

## Hot Spot Comparison |

| The hot spot comparison is one of the CPU comparisons. It is created by invoking the CPU comparison wizard. For more information on snapshot comparisons, please see the snapshot comparison overview.

| The wizard has the following additional steps: Select snapshots The hot spot comparison compares two snapshot files. In this step, you select the first and the second snapshot file for the comparison. The combo boxes contain all snapshot files that have been added to the snapshot selector. You can use the same snapshot file for the first and second snapshot file, in which case the thread selections in the next step must be different. Thread selection In this step, you choose for which threads the comparison should be made. By default all threads are selected, you can restrict the thread selection to single thread groups or single threads. View parameters In this steps you can select thread status, aggregation level and filtered classes handling, just as for the hot spots view. In addition, you can choose whether to calculate differences of total call times or of average call times (total time divided by invocation count). Note that if "Sampling" was used as the method call recording type, the invocation count is not available and this setting will not have any effect.

| Each row in the hot spot comparison has the following columns: the name of the hot spot the inherent time in the second snapshot file minus the inherent time in the first snapshot file the invocations in the second snapshot file minus the invocations in the first snapshot file The second column incorporates a bidirectional bar chart. Increases are painted in red and to the right, while decreases are painted in green and to the left. In the view settings dialog you can choose whether you want this bar chart to display absolute changes or the percentage of the change. The other value is displayed in parentheses. This setting also determines how this column is sorted.

| By default, only hot spots that have changed from one snapshot file to the other are displayed. You can change this behavior in the view settings dialog.

| At the bottom of the hot spot comparison is a view filter selector that filters data for specific package or class names.