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

[stephane ducasse]

Andreas

thanks for the fix. Now I imagine that henrik is on holidays (I cannot ask him what was the intention of his changes).
Am'I correct to suspect that the bug is due to the fact that == are not preemptable while the code of pharo definition using
plain message sends can be interrupted?

Stef

On Dec 31, 2010, at 10:32 AM, Andreas Raab wrote:

> Oh, I also just noticed something else: It seems as if the VMMaker changes for atomic suspend never made it into the main line. I just posted the relevant bits but that means you have another workaround. You can use the Cog VM, which has had these changes from the beginning. By using Cog, the primitive suspend will never fail and consequently the (still broken) code in LinkedList>>remove:ifAbsent: will never be executed.
> 
> Cheers,
>  - Andreas
> 
> On 12/31/2010 10:08 AM, Andreas Raab wrote:
>> 
>> 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
>>> ------------------------------------------------------------
>>