[squeak-dev] trunk image locked (was: The Inbox: Kernel-eem.1185.mcz)
Levente Uzonyi
leves at caesar.elte.hu
Thu Aug 2 11:52:58 UTC 2018
Hi Chris,
Did you try to send SIGUSR1 to this image before killing it? (assuming it
didn't happen on Windows)
Levente
On Wed, 1 Aug 2018, Chris Muller wrote:
> My image just locked after it tried to unwind normally from a network
> timeout. I had to kill it from the OS.
>
> Eliot would you guide me how to get my trunk image rolled back to a
> state without this fix so I can try to get back to where I was to see
> if its related?
>
> Should I just load Kernel-eem.1184, an earlier one,
> or something else?
>
>
>
> On Fri, Jul 27, 2018 at 1:08 PM, <commits at source.squeak.org> wrote:
>> A new version of Kernel was added to project The Inbox:
>> http://source.squeak.org/inbox/Kernel-eem.1185.mcz
>>
>> ==================== Summary ====================
>>
>> Name: Kernel-eem.1185
>> Author: eem
>> Time: 27 July 2018, 11:08:12.641836 am
>> UUID: 7296ad00-708d-4cef-b6bc-ceb24d897a70
>> Ancestors: Kernel-eem.1184
>>
>> In releaseCriticalSection: use isUnwindContext instead of the more fragile context selector == #ensure:. Now it will handle ifCurtailed: too. Thanks Tobias!
>>
>> Reformat Process>>#terminate. It was baaad.
>>
>> =============== Diff against Kernel-eem.1184 ===============
>>
>> Item was changed:
>> ----- Method: Process>>releaseCriticalSection: (in category 'private') -----
>> releaseCriticalSection: runnable
>> "Figure out if we are terminating a process that is in the ensure: block of a critical section.
>> In this case, if the block has made progress, pop the suspendedContext so that we leave the
>> ensure: block inside the critical: without signaling the semaphore/exiting the primitive section,
>> since presumably this has already happened. But if it hasn't made progress but is beyond the
>> + wait (which we can tell by the oldList being one of the runnable lists, i.e. a LinkedList, not a
>> - wait (which we can tell my the oldList being one of the runnable lists, i.e. a LinkedList, not a
>> Semaphore or Mutex, et al), then the ensure: block needs to be run."
>> | selectorJustSent |
>> (suspendedContext method pragmaAt: #criticalSection) ifNil: [^self].
>> selectorJustSent := suspendedContext selectorJustSentOrSelf.
>>
>> "Receiver and/or argument blocks of ensure: in Semaphore>>critical: or Mutex>>#critical:"
>> suspendedContext isClosureContext ifTrue:
>> + [suspendedContext sender isUnwindContext ifTrue:
>> - [suspendedContext sender selector == #ensure: ifTrue:
>> [| notWaitingButMadeNoProgress |
>> "Avoid running the ensure: block twice, popping it if it has already been run. If runnable
>> but at the wait, leave it in place. N.B. No need to check if the block receiver of ensure: has
>> not started to run (via suspendedContext pc = suspendedContext startpc) because ensure:
>> uses valueNoContextSwitch, and so there is no suspension point before the wait."
>> notWaitingButMadeNoProgress :=
>> runnable
>> and: [selectorJustSent == #wait
>> and: [suspendedContext sender selectorJustSentOrSelf == #valueNoContextSwitch]].
>> notWaitingButMadeNoProgress ifFalse:
>> [suspendedContext := suspendedContext home]].
>> ^self].
>>
>> "Either Semaphore>>critical: or Mutex>>#critical:. Is the process still blocked? If so, nothing further to do."
>> runnable ifFalse: [^self].
>>
>> "If still at the wait the ensure: block has not been activated, so signal to restore."
>> selectorJustSent == #wait ifTrue:
>> [suspendedContext receiver signal].
>>
>> "If still at the lock primitive and the lock primitive just acquired ownership (indicated by it answering false)
>> then the ensure block has not been activated, so explicitly primitiveExitCriticalSection to unlock."
>> (selectorJustSent == #primitiveEnterCriticalSection
>> or: [selectorJustSent == #primitiveTestAndSetOwnershipOfCriticalSection]) ifTrue:
>> [(suspendedContext stackPtr > 0
>> and: [suspendedContext top == false]) ifTrue:
>> [suspendedContext receiver primitiveExitCriticalSection]]!
>>
>> Item was changed:
>> ----- Method: Process>>terminate (in category 'changing process state') -----
>> terminate
>> "Stop the process that the receiver represents forever.
>> Unwind to execute pending ensure:/ifCurtailed: blocks before terminating.
>> If the process is in the middle of a critical: critical section, release it properly."
>>
>> | ctxt unwindBlock oldList |
>> + self isActiveProcess ifTrue:
>> + [ctxt := thisContext.
>> + [ctxt := ctxt findNextUnwindContextUpTo: nil.
>> + ctxt ~~ nil] whileTrue:
>> + [(ctxt tempAt: 2) ifNil:
>> + ["N.B. Unlike Context>>unwindTo: we do not set complete (tempAt: 2) to true."
>> + unwindBlock := ctxt tempAt: 1.
>> + thisContext terminateTo: ctxt.
>> + unwindBlock value]].
>> - self isActiveProcess ifTrue: [
>> - ctxt := thisContext.
>> - [ ctxt := ctxt findNextUnwindContextUpTo: nil.
>> - ctxt isNil
>> - ] whileFalse: [
>> - (ctxt tempAt: 2) ifNil:[
>> - ctxt tempAt: 2 put: nil.
>> - unwindBlock := ctxt tempAt: 1.
>> - thisContext terminateTo: ctxt.
>> - unwindBlock value].
>> - ].
>> thisContext terminateTo: nil.
>> self suspend.
>> + "If the process is resumed this will provoke a cannotReturn: error.
>> + Would self debug: thisContext title: 'Resuming a terminated process' be better?"
>> + ^self].
>> - ] ifFalse:[
>> - "Always suspend the process first so it doesn't accidentally get woken up.
>> - N.B. If oldList is a LinkedList then the process is runnable. If it is a Semaphore/Mutex et al
>> - then the process is blocked, and if it is nil then the process is already suspended."
>> - oldList := self suspend.
>> - suspendedContext ifNotNil:
>> - ["Release any method marked with the <criticalSection> pragma.
>> - The argument is whether the process is runnable."
>> - self releaseCriticalSection: (oldList isNil or: [oldList class == LinkedList]).
>>
>> + "Always suspend the process first so it doesn't accidentally get woken up.
>> + N.B. If oldList is a LinkedList then the process is runnable. If it is a Semaphore/Mutex et al
>> + then the process is blocked, and if it is nil then the process is already suspended."
>> + oldList := self suspend.
>> + suspendedContext ifNotNil:
>> + ["Release any method marked with the <criticalSection> pragma.
>> + The argument is whether the process is runnable."
>> + self releaseCriticalSection: (oldList isNil or: [oldList class == LinkedList]).
>> - "If terminating a process halfways through an unwind, try to complete that unwind block first."
>> - (suspendedContext findNextUnwindContextUpTo: nil) ifNotNil:
>> - [:outer|
>> - (suspendedContext findContextSuchThat:[:c| c closure == (outer tempAt: 1)]) ifNotNil:
>> - [:inner| "This is an unwind block currently under evaluation"
>> - suspendedContext runUntilErrorOrReturnFrom: inner]].
>>
>> + "If terminating a process halfways through an unwind, try to complete that unwind block first."
>> + (suspendedContext findNextUnwindContextUpTo: nil) ifNotNil:
>> + [:outer|
>> + (suspendedContext findContextSuchThat:[:c| c closure == (outer tempAt: 1)]) ifNotNil:
>> + [:inner| "This is an unwind block currently under evaluation"
>> + suspendedContext runUntilErrorOrReturnFrom: inner]].
>> +
>> + ctxt := self popTo: suspendedContext bottomContext.
>> + ctxt == suspendedContext bottomContext ifFalse:
>> + [self debug: ctxt title: 'Unwind error during termination'].
>> + "Set the context to its endPC for the benefit of isTerminated."
>> + ctxt pc: ctxt endPC]!
>> - ctxt := self popTo: suspendedContext bottomContext.
>> - ctxt == suspendedContext bottomContext ifFalse:
>> - [self debug: ctxt title: 'Unwind error during termination'].
>> - "Set the context to its endPC for the benefit of isTerminated."
>> - ctxt pc: ctxt endPC]]!
>>
>>
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