3.6 Visualization
The local host can generate informations about the dynamic behaviour
of the distributed system. These informations are inferred from
messages that are received from the other machines, and therefore they
might be delayed. There are two possibilities for the visualization of
these informations:
- Online Visualization: It opens a window of desired size,
which displays the execution status of all connected machines
for the last period of time. In the upper half of the window, it is
shown for each machine whether it is active or not (a horizontal
line indicates that the corresponding machine is executing a
task). In the lower half of the window, a diagram is shown that
indicates how many machines are active at each moment (see Figure
3.6).
Online visualization
- Post-Execution Visualization: During a distributed
session, a tracefile with the relevant events can be generated.
After the session is ended, the following call from the command line:
java visual.Main filename start end width height
will generate some files, each of them containing a diagram of
dimension width×height millimeters that visualizes some
aspects of the program's runtime behavior, for the interval between
the labeled moments start and end. The generated files are
the following:
- filename-machines.fig (Figure 3.6) displays
by a horizontal bar those times when a machine was active
executing a task; a short vertical bar denotes some load-changing
event occurring at that particular time (e.g., waiting for a new
task to be executed);
Post-Execution Visualization: filename-machines.fig
- filename-util.fig (Figure 3.6) displays the
number of active machines at a time;
Post-Execution Visualization: filename-util.fig
- filename-tasks.fig (Figure 3.6) displays
the interval of time during which each task was executed, and by
which machine;
Post-Execution Visualization: filename-tasks.fig
The numbers at the bottom of each diagram denote the range of the
visualization time in milliseconds. The vertical dashed lines
represents execution labels. There are two predefined labels,
initialize and terminate, but the user can define at
any time of the execution other labels. These labels can be used for
restricting the visualization range.
Commands for visualization:
Maintained by: Cleo Pau
Last Modification: July 5, 2000