|duration benchmarkResult sem backgroundProcess|  	
  backgroundProcess := nil.
  sem := nil.
  100 timesRepeat: [ 
	  Monitor new critical: [  
			backgroundProcess
				ifNotNil: [
					backgroundProcess terminate.
					backgroundProcess := nil].
			sem
				ifNotNil: [
					sem terminateProcess.
					sem := nil].
			sem := Semaphore new.
			[ 
				sem notNil
					ifTrue: [ 
						sem 
							waitTimeoutSeconds: 10
							onCompletion: [ 'done' logCr ]
							onTimeout: [ 'timeout' logCr ] ] 
			] forkAt: Processor activePriority.
		
			backgroundProcess := [ 
				"10000 timesRepeat: [ 1000 factorial ]."
				sem signal ] forkAt: Processor userBackgroundPriority  ]
		].
	backgroundProcess
		ifNotNil: [
			backgroundProcess terminate.
			backgroundProcess := nil].
	sem
		ifNotNil: [
			sem terminateProcess.
			sem := nil].

	duration := 100 milliSeconds.
	benchmarkResult := [ 100 factorial ] benchFor: duration.