fix: memory leak in utilityProcessWorkerMainService - #294005

Fixes a memory leak in utilityProcessWorkerMainService.

Details

In utilityProcessWorkerMainService, when a worker is terminated, it is removed from the this.workers map. But the worker itself seems be not be disposed.

Event.once(worker.onDidTerminate)(reason => {
    /* ... */
	this.workers.delete(workerId);
	onDidTerminate.complete({ reason });
});

Change

The change uses a DisposableMap so that the worker is be deleted from the map and also gets disposed.

Event.once(worker.onDidTerminate)(reason => {
	/* ... */
	this.workers.deleteAndDispose(workerId);
	onDidTerminate.complete({ reason });
});

Another related (but not really important) change is removing some cleanup code from disposeWorker which seems to be already handled by worker.onDidTerminate.

worker.kill();
 ̶w̶o̶r̶k̶e̶r̶.̶d̶i̶s̶p̶o̶s̶e̶(̶)̶;̶
̶t̶h̶i̶s̶.̶w̶o̶r̶k̶e̶r̶s̶.̶d̶e̶l̶e̶t̶e̶(̶w̶o̶r̶k̶e̶r̶I̶d̶)̶;̶

Before

When opening and closing a window 17 times, the number of various utility process functions seems to grow each time.

After

When opening and closing a window 17 times, the number of utility process functions stays constant: