Hot Spot Comparison
-
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 self time in the second
snapshot file minus the self 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.