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<p class="MsoNormal">Hi again,</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> From: Nicolas Cellier</p>
<p class="MsoNormal"> Sent: Sunday, May 8, 2022 18:16</p>
<p class="MsoNormal"> To: The general-purpose Squeak developers list</p>
<p class="MsoNormal"> Subject: Re: [squeak-dev] SIGTRAP when Proceeding from BlockCannotReturn</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> > I have the impression that DelayWaitTimeout depends on the old primitiveSuspend (#88) behavior:</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> signalWaitingProcess</p>
<p class="MsoNormal"> "Release the given process from the semaphore it is waiting on.</p>
<p class="MsoNormal"> This method relies on running at highest priority so that it cannot be preempted</p>
<p class="MsoNormal"> by the process being released."</p>
<p class="MsoNormal"> beingWaitedOn := false.</p>
<p class="MsoNormal"> "Release the process but only if it is still waiting on its original list"</p>
<p class="MsoNormal"> process suspendingList == delaySemaphore ifTrue:[</p>
<p class="MsoNormal"> expired := true.</p>
<p class="MsoNormal"> process suspend; resume.</p>
<p class="MsoNormal"> ].</p>
<p class="MsoNormal"> > My understanding is that this code assumes that suspending, then resuming will remove the waiting process from the list.</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> Yes, that’s exactly the problem; I’m enclosing the fix:</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> signalWaitingProcess</p>
<p class="MsoNormal"> "Release the given process from the semaphore it is waiting on.</p>
<p class="MsoNormal"> This method relies on running at highest priority so that it cannot be preempted</p>
<p class="MsoNormal"> by the process being released."</p>
<p class="MsoNormal"> | list |</p>
<p class="MsoNormal"> beingWaitedOn := false.</p>
<p class="MsoNormal"> "Release the process but only if it is still waiting on its original list"</p>
<p class="MsoNormal"> (list := process suspendingList) == delaySemaphore ifTrue:[</p>
<p class="MsoNormal"> expired := true.</p>
<p class="MsoNormal"> list remove: self ifAbsent:[].
</p>
<p class="MsoNormal"> process offList; resume]</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> Maybe it's `list remove: process ifAbsent: []` instead.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Oh my, I have no idea why I put ‘self’ in there :) Thanks!</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> Excavating offList usage would require an update of its comment...</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Ha ha, "excavating offList" :D</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> Also, see why manipulating the list from within the image might be dangerous</p>
<p class="MsoNormal"> http://forum.world.st/Process-gt-gt-terminate-woes-td69405.html</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you, very interesting... sounds like this fix may be too tricky without using #suspend</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best,</p>
<p class="MsoNormal">Jaromir</p>
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