[squeak-dev] trunk image locked (was: The Inbox: Kernel-eem.1185.mcz)

Chris Muller asqueaker at gmail.com
Thu Aug 2 01:55:57 UTC 2018


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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