[Vm-dev] Image freeze because handleTimerEvent and Seaside process gone?!

[Andreas Raab]

Revert LinkedList>>remove:ifAbsent: back to the version in Squeak and 
your problems will go away.

Cheers,
   - Andreas

On 12/30/2010 11:50 PM, Adrian Lienhard wrote:
>
> Thanks Andreas and David for the responses!
>
> In the meantime I've gathered more information. From the mail of Andreas I assumed that the most likely reason for the freeze is that the timer event loop throws an unhandled exception and therefore gets suspended.
>
> So I added a guard to catch any error in handleTimerEvent, restart the loop, and then pass the exception to open a debugger:
>
> runTimerEventLoop
> 	[RunTimerEventLoop] whileTrue: [
> 		[ self handleTimerEvent ]
> 			on: Error
> 			do: [ :e |
> 				self startTimerEventLoop.
> 				...write a warning to stdout...
> 				e pass ] ]
>
> And voila, after 10 days or so I got the stack trace below.
>
> I haven't had time to dive into it, but from the stack it seems like a concurrency issue in linked list (although I wonder whether that's possible since the timer event loop runs at the highest priority...).
>
> Maybe something catches somebody's eye.
>
> Cheers,
> Adrian
>
>
> THERE_BE_DRAGONS_HERE
> Error: no such method!
> 30 December 2010 10:32:28 pm
>
> VM: unix - i686 - linux - Squeak3.10.2 of '5 June 2008' [latest update: #7179]
> Image: Pharo1.1 [Latest update: #11410]
>
> Semaphore(Object)>>error:
> 	Receiver: a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 	Arguments and temporary variables:
> 		t1: 	'no such method!'
> 	Receiver's instance variables:
> 		firstLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		lastLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		excessSignals: 	0
>
>
> [] in Semaphore(LinkedList)>>removeLink:
> 	Receiver: a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 	Arguments and temporary variables:
>
> 	Receiver's instance variables:
> 		firstLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		lastLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		excessSignals: 	0
>
>
> Semaphore(LinkedList)>>removeLink:ifAbsent:
> 	Receiver: a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 	Arguments and temporary variables:
> 		aLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		aBlock: 	[self error: 'no such method!']
> 		tempLink: 	nil
> 	Receiver's instance variables:
> 		firstLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		lastLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		excessSignals: 	0
>
>
> Semaphore(LinkedList)>>removeLink:
> 	Receiver: a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 	Arguments and temporary variables:
> 		aLink: 	a Process in [] in DelayWaitTimeout>>wait
> 	Receiver's instance variables:
> 		firstLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		lastLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		excessSignals: 	0
>
>
> Semaphore(LinkedList)>>remove:ifAbsent:
> 	Receiver: a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 	Arguments and temporary variables:
> 		aLinkOrObject: 	a Process in [] in DelayWaitTimeout>>wait
> 		aBlock: 	[]
> 		link: 	a Process in [] in DelayWaitTimeout>>wait
> 	Receiver's instance variables:
> 		firstLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		lastLink: 	a Process in [] in DelayWaitTimeout>>wait
> 		excessSignals: 	0
>
>
> Process>>suspend
> 	Receiver: a Process in [] in DelayWaitTimeout>>wait
> 	Arguments and temporary variables:
> 		t1: 	a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 	Receiver's instance variables:
> 		nextLink: 	nil
> 		suspendedContext: 	[] in DelayWaitTimeout>>wait
> 		priority: 	30
> 		myList: 	a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 		errorHandler: 	nil
> 		name: 	'seaside'
> 		env: 	nil
>
>
> DelayWaitTimeout>>signalWaitingProcess
> 	Receiver: a DelayWaitTimeout(10000 msecs)
> 	Arguments and temporary variables:
>
> 	Receiver's instance variables:
> 		delayDuration: 	10000
> 		resumptionTime: 	217048389
> 		delaySemaphore: 	a Semaphore(a Process in [] in DelayWaitTimeout>>wait)
> 		beingWaitedOn: 	false
> 		process: 	a Process in [] in DelayWaitTimeout>>wait
> 		expired: 	true
>
>
> Delay class>>handleTimerEvent
> 	Receiver: Delay
> 	Arguments and temporary variables:
> 		t1: 	217128602
> 		t2: 	nil
> 	Receiver's instance variables:
> 		superclass: 	Object
> 		methodDict: 	a MethodDictionary(#adjustResumptionTimeOldBase:newBase:->(Delay>>#...etc...
> 		format: 	138
> 		instanceVariables: 	#('delayDuration' 'resumptionTime' 'delaySemaphore' 'beingWa...etc...
> 		organization: 	('as yet unclassified' adjustResumptionTimeOldBase:newBase: being...etc...
> 		subclasses: 	{MonitorDelay. DelayWaitTimeout}
> 		name: 	#Delay
> 		classPool: 	a Dictionary(#AccessProtect->a Semaphore() #ActiveDelay->a Delay(10 ...etc...
> 		sharedPools: 	nil
> 		environment: 	a SystemDictionary(lots of globals)
> 		category: 	#'Kernel-Processes'
> 		traitComposition: 	{}
> 		localSelectors: 	nil
>
>
> [] in Delay class>>runTimerEventLoop
> 	Receiver: Delay
> 	Arguments and temporary variables:
>
> 	Receiver's instance variables:
> 		superclass: 	Object
> 		methodDict: 	a MethodDictionary(#adjustResumptionTimeOldBase:newBase:->(Delay>>#...etc...
> 		format: 	138
> 		instanceVariables: 	#('delayDuration' 'resumptionTime' 'delaySemaphore' 'beingWa...etc...
> 		organization: 	('as yet unclassified' adjustResumptionTimeOldBase:newBase: being...etc...
> 		subclasses: 	{MonitorDelay. DelayWaitTimeout}
> 		name: 	#Delay
> 		classPool: 	a Dictionary(#AccessProtect->a Semaphore() #ActiveDelay->a Delay(10 ...etc...
> 		sharedPools: 	nil
> 		environment: 	a SystemDictionary(lots of globals)
> 		category: 	#'Kernel-Processes'
> 		traitComposition: 	{}
> 		localSelectors: 	nil
>
>
> BlockClosure>>on:do:
> 	Receiver: [self handleTimerEvent]
> 	Arguments and temporary variables:
> 		exception: 	Error
> 		handlerAction: 	[:e |
> self startTimerEventLoop.
> 	FileStream
> 		fileNamed: '/dev/...etc...
> 		handlerActive: 	false
> 	Receiver's instance variables:
> 		outerContext: 	Delay class>>runTimerEventLoop
> 		startpc: 	108
> 		numArgs: 	0
>
>
> Delay class>>runTimerEventLoop
> 	Receiver: Delay
> 	Arguments and temporary variables:
>
> 	Receiver's instance variables:
> 		superclass: 	Object
> 		methodDict: 	a MethodDictionary(#adjustResumptionTimeOldBase:newBase:->(Delay>>#...etc...
> 		format: 	138
> 		instanceVariables: 	#('delayDuration' 'resumptionTime' 'delaySemaphore' 'beingWa...etc...
> 		organization: 	('as yet unclassified' adjustResumptionTimeOldBase:newBase: being...etc...
> 		subclasses: 	{MonitorDelay. DelayWaitTimeout}
> 		name: 	#Delay
> 		classPool: 	a Dictionary(#AccessProtect->a Semaphore() #ActiveDelay->a Delay(10 ...etc...
> 		sharedPools: 	nil
> 		environment: 	a SystemDictionary(lots of globals)
> 		category: 	#'Kernel-Processes'
> 		traitComposition: 	{}
> 		localSelectors: 	nil
>
>
> [] in Delay class>>startTimerEventLoop
> 	Receiver: Delay
> 	Arguments and temporary variables:
>
> 	Receiver's instance variables:
> 		superclass: 	Object
> 		methodDict: 	a MethodDictionary(#adjustResumptionTimeOldBase:newBase:->(Delay>>#...etc...
> 		format: 	138
> 		instanceVariables: 	#('delayDuration' 'resumptionTime' 'delaySemaphore' 'beingWa...etc...
> 		organization: 	('as yet unclassified' adjustResumptionTimeOldBase:newBase: being...etc...
> 		subclasses: 	{MonitorDelay. DelayWaitTimeout}
> 		name: 	#Delay
> 		classPool: 	a Dictionary(#AccessProtect->a Semaphore() #ActiveDelay->a Delay(10 ...etc...
> 		sharedPools: 	nil
> 		environment: 	a SystemDictionary(lots of globals)
> 		category: 	#'Kernel-Processes'
> 		traitComposition: 	{}
> 		localSelectors: 	nil
>
>
> [] in BlockClosure>>newProcess
> 	Receiver: [self runTimerEventLoop]
> 	Arguments and temporary variables:
>
> 	Receiver's instance variables:
> 		outerContext: 	Delay class>>startTimerEventLoop
> 		startpc: 	144
> 		numArgs: 	0
>
>
>
> --- The full stack ---
> Semaphore(Object)>>error:
> [] in Semaphore(LinkedList)>>removeLink:
> Semaphore(LinkedList)>>removeLink:ifAbsent:
> Semaphore(LinkedList)>>removeLink:
> Semaphore(LinkedList)>>remove:ifAbsent:
> Process>>suspend
> DelayWaitTimeout>>signalWaitingProcess
> Delay class>>handleTimerEvent
> [] in Delay class>>runTimerEventLoop
> BlockClosure>>on:do:
> Delay class>>runTimerEventLoop
> [] in Delay class>>startTimerEventLoop
> [] in BlockClosure>>newProcess
> ------------------------------------------------------------