debugger into on dead process hangs image

[j-brant]

If you have a dead process in a debugger and press the Into, the image hangs. For example, if you evaluate

	| process context |
	process := [  ] newProcess.
	context := process suspendedContext.
	context pc: nil.
	process debug

and then hit the Into button, the image hangs. It appears that I get an ever growing stack of CompiledMethod(Object)>>at:. Here's the stack of one of my runs:

 ByteString(SequenceableCollection)>>do:
 ZnNewLineWriterStream(Stream)>>nextPutAll:
 ZnNewLineWriterStream(WriteStream)>>nextPutAll:
 Context>>printOn:
 ZnNewLineWriterStream(Stream)>>print:
 Context>>errorReportOn:
 [ :logger | 
logger
	nextPutAll: 'THERE_BE_DRAGONS_HERE';
	cr;
	nextPutAll: errMsg;
	cr.
"just print the error message if no context is given"
aContext ifNotNil: [ aContext errorReportOn: logger ].
" write some type of separator"
logger
	nextPutAll: (String new: 79 withAll: $-);
	cr;
	cr ] in SmalltalkImage>>logError:inContext:
 [ logStream := self openLog.
aMonadicBlock value: logStream ] in SmalltalkImage>>logDuring:
 BlockClosure>>ensure:
 SmalltalkImage>>logDuring:
 SmalltalkImage>>logError:inContext:
 [ Smalltalk logError: name inContext: interruptedContext ] in [ [ Smalltalk logError: name inContext: interruptedContext ]
	ifError: [  ] ] in DebugSession>>logStackToFileIfNeeded
 BlockClosure>>on:do:
 BlockClosure>>ifError:
 [ [ Smalltalk logError: name inContext: interruptedContext ]
	ifError: [  ] ] in DebugSession>>logStackToFileIfNeeded
 BlockClosure>>ensure:
 [ watchdog resume.	"start up the watchdog"
self
	ensure: [ "evaluate the receiver"
		theProcess := nil.	"it has completed, so ..."
		delay delaySemaphore signal	"arrange for the watchdog to exit" ] ] in BlockClosure>>valueWithin:onTimeout:
 BlockClosure>>on:do:
 BlockClosure>>valueWithin:onTimeout:
 DebugSession>>logStackToFileIfNeeded
 MorphicUIManager>>debugProcess:context:label:fullView:notification:
 MorphicUIManager(UIManager)>>debugProcess:context:label:fullView:
 Process>>debug:title:full:
 Process>>debug:title:
 SubscriptOutOfBounds(Exception)>>debug
 MorphicUIManager>>unhandledErrorDefaultAction:
 UnhandledError>>defaultAction
 UndefinedObject>>handleSignal:
 UnhandledError(Exception)>>signal
 UnhandledError class>>signalForException:
 SubscriptOutOfBounds(Error)>>defaultAction
 UndefinedObject>>handleSignal:
 SubscriptOutOfBounds(Exception)>>pass
 [ :ex | 
ActiveWorld := priorWorld.
ActiveEvent := priorEvent.
ActiveHand := priorHand.
ex pass ] in WorldMorph>>becomeActiveDuring:
 BlockClosure>>cull:
 Context>>evaluateSignal:
 Context>>handleSignal:
 SubscriptOutOfBounds(Exception)>>signal
 SubscriptOutOfBounds class>>signalFor:lowerBound:upperBound:in:
 SubscriptOutOfBounds class>>signalFor:lowerBound:upperBound:
 SubscriptOutOfBounds class>>signalFor:
 CompiledMethod(Object)>>errorSubscriptBounds:
 CompiledMethod(Object)>>at:
 CompiledMethod(Object)>>at:
...a few hundred more at: methods...
 CompiledMethod(Object)>>at:
 CompiledMethod(Object)>>at:
 CompiledMethod(SequenceableCollection)>>collect:
 SmallInteger(Number)>>adaptToCollection:andSend:
 CompiledMethod(Collection)>>//
 Context(InstructionStream)>>interpretNextV3PlusClosureInstructionFor:
 EncoderForV3PlusClosures class>>interpretNextInstructionFor:in:
 Context(InstructionStream)>>interpretNextInstructionFor:
 Context>>step
 [ self suspendedContext == aContext
	ifTrue: [ suspendedContext := suspendedContext step ]
	ifFalse: [ self complete: (self calleeOf: aContext) ] ] in Process>>step:
 BlockClosure>>ensure:
 Process>>evaluate:onBehalfOf:
 Process>>step:
 DebugSession>>stepInto:
 StepIntoDebugAction>>executeAction
 StepIntoDebugAction(DebugAction)>>execute
 [ self execute ] in StepIntoDebugAction(DebugAction)>>asGlamourAction
 BlockClosure>>glamourValueWithArgs:
 GLMGenericAction(GLMAction)>>actOn:
 GLMGenericAction(GLMAction)>>morphicActOn:
 GLMPluggableButtonMorph(PluggableButtonMorph)>>performAction:
 [ :m | 
(m containsPoint: evt cursorPoint)
	ifTrue: [ m enabled
			ifTrue: [ m performAction: evt ] ] ] in GLMPluggableButtonMorph(PluggableButtonMorph)>>mouseUp:
 Array(SequenceableCollection)>>do:
 GLMPluggableButtonMorph(PluggableButtonMorph)>>mouseUp:
 GLMPluggableButtonMorph(Morph)>>handleMouseUp:
 MouseButtonEvent>>sentTo:
 GLMPluggableButtonMorph(Morph)>>handleEvent:
 GLMPluggableButtonMorph(Morph)>>handleFocusEvent:
 [ ActiveHand := self.
ActiveEvent := anEvent.
result := focusHolder
	handleFocusEvent: (anEvent transformedBy: (focusHolder transformedFrom: self)) ] in HandMorph>>sendFocusEvent:to:clear:
 BlockClosure>>on:do:
 WorldMorph>>becomeActiveDuring:
 HandMorph>>sendFocusEvent:to:clear:
 HandMorph>>sendEvent:focus:clear:
 HandMorph>>sendMouseEvent:
 HandMorph>>handleEvent:
 HandMorph>>processEventsFromQueue:
 HandMorph>>processEvents
 [ :h | 
self activeHand: h.
h processEvents.
self activeHand: nil ] in WorldState>>doOneCycleNowFor:
 Array(SequenceableCollection)>>do:
 WorldState>>handsDo:
 WorldState>>doOneCycleNowFor:
 WorldState>>doOneCycleFor:
 WorldMorph>>doOneCycle
 WorldMorph class>>doOneCycle
 [ [ WorldMorph doOneCycle.
Processor yield.
false ] whileFalse: [  ] ] in MorphicUIManager>>spawnNewProcess
 [ self value.
Processor terminateActive ] in BlockClosure>>newProcess

[StephanEggermont]

Yes, I've run into this problem too

[StevenCostiou]

Should we be able to step a dead context?

In P9, the debugger does not allows you to do that (buttons are disabled) - except that your examples highlights another bug in the debugger (will fix).

Did you step the dead context on purpose, and how should it work? Or would the stepping being disabled with a notification that you cannot step a dead context suffice?

[StephanEggermont]

One click too many...