6.6: The Process Browser

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Andrew P. Black, Stéphane Ducasse, Oscar Nierstrasz, Damien Pollet

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Smalltalk is a multi-threaded system: there are many lightweight processes (also known as threads) running concurrently in your image. In the future the Squeak virtual machine may take advantage of multiprocessors when they are available, but at present concurrency is implemented by time-slicing.

The process browser is a cousin of the debugger that lets you look at the various processes running inside Squeak. Figure \(\PageIndex{1}\) shows a screenshot. The top-left pane lists all of the processes in Squeak, in priority order, from the timer interrupt watcher at priority 80 to the idle process at priority 10. Of course, on a uniprocessor, the only process that can be running when you look is the UI process; all of the other will be waiting for some kind of event. By default, the display of processes is static; it can be updated using the yellow button menu, which also provides an option to turn on auto-update (a).

If you select a process in the top-left pane, its stack trace is displayed in the top-right pane, just as with the debugger. If you select a stack frame, the corresponding method is displayed in the bottom pane. The process browser is not equipped with mini-inspectors for self and thisContext, but yellow button menu items on the stack frames provide equivalent functionality.