A new version of System was added to project The Inbox:
http://source.squeak.org/inbox/System-ael.488.mcz

==================== Summary ====================

Name: System-ael.488
Author: ael
Time: 10 July 2012, 1:56:20.102 pm
UUID: 18e76459-4ed0-478c-b2b3-9d587d1f6b3d
Ancestors: System-eem.487

Tentative fix for 'tally is already running' error when profiling from ProcessBrowser.

=============== Diff against System-eem.487 ===============

Item was changed:
  ----- Method: MessageTally>>spyEvery:onProcess:forMilliseconds: (in category 'initialize-release') -----
  spyEvery: millisecs onProcess: aProcess forMilliseconds: msecDuration 
  	"Create a spy and spy on the given process at the specified rate."
  	| myDelay time0 endTime observedProcess sem |
  	(aProcess isKindOf: Process)
  		ifFalse: [self error: 'spy needs a Process here'].
  	self class: aProcess suspendedContext receiver class method: aProcess suspendedContext method.
  	"set up the probe"
  	observedProcess := aProcess.
  	myDelay := Delay forMilliseconds: millisecs.
  	time0 := Time millisecondClockValue.
  	endTime := time0 + msecDuration.
  	sem := Semaphore new.
  	gcStats := SmalltalkImage current getVMParameters.
  	Timer ifNotNil: [ self error: 'it seems a tally is already running' ].
  	Timer := [
  			[
  				| startTime |
  				startTime := Time millisecondClockValue.
  				myDelay wait.
  				self
  					tally: Processor preemptedProcess suspendedContext
  					in: (observedProcess == Processor preemptedProcess 
  						ifTrue: [ observedProcess ]
  						ifFalse: [ nil ])
  					"tally can be > 1 if ran a long primitive"
  					by: (Time millisecondClockValue - startTime) // millisecs.
  				startTime < endTime
  			] whileTrue.
  			sem signal.
  		] newProcess.
  	Timer priority: Processor timingPriority-1.
  		"activate the probe and evaluate the block"
  	Timer resume.
  	"activate the probe and wait for it to finish"
  	sem wait.
+ 	Timer ifNotNil: [
+ 		Timer terminate.
+ 		Timer := nil ].
  	"Collect gc statistics"
  	SmalltalkImage current getVMParameters keysAndValuesDo: [ :idx :gcVal |
  		gcVal ifNotNil: [ gcStats at: idx put: (gcVal - (gcStats at: idx)) ] ].
  	time := Time millisecondClockValue - time0!