Tuesday, July 24, 2001

This shot illustrates that I've removed the Events menu from the menu bar (see shot 2 of a previous report). Instead, I've created a new window that deals with events filtering. Description follows below.

Shot 2: Event Filter Settings Window

The above is the Event Filter Settings window (I used to have it before but I've recently revamped it and added more functionality). Using it, the user can control four aspects of each event.

• Enabled. This simply denotes whether the corresponding event will cause the VM to transmit data to the visualiser. If an event is not enabled, then the VM will not spend any time gathering data and transmitting it, hence that event will not cause any performance penalty to the VM.
• Delay. After the corresponding event has caused the VM to transmit its state to the visualiser, the system will pause for the given amount of time. This essentially slows down some events so that the user can have the opportunity to take a closer look to what's being transmitted.
• Pause. This forces the system to pause after transmission of the corresponding event. So, if the user is interested in a particular event, they will not have to wait ready to press the Pause button; the system will pause itself.
• Skip. This causes the system to skip a number of events of a given kind in order to get a better trade-off between how much you see and how slow the system is. So, by skipping say 2 events (i.e. every third will be transmitted), the user will not see all the GC operation, but the system will run at a higher speed. Again, if an event is skipped, the VM does not gather data and transmit.

The GCspy code at the server maintains a counter for every event that it comes across, irrespective to whether the event was transmitted to the visualiser or not (see above for reasons not to transmit some events). These counters are now sent to the visualiser along with every new transmission and shown in the Event Counters shown above.

Shot 4: All Windows

This gives an impression of what GCspy looks like when all its windows open (minus the Trace Window, described in a previous report).