[Pharo-fuel] [Vm-dev] Fwd: Possible collections problem

Max Leske maxleske at gmail.com
Tue Jun 4 18:14:01 UTC 2013

> I don't think there that there is anything about a Smalltalk Semaphore that
> would be affected by the #forkSqueak. The state of the semaphore would be
> identical in the forked image and in its parent image, and all state variables
> in the VM would also be the same.
> However, it does seem quite possible that running an image (forked or not)
> with its X11 display shut off might lead to problems after a while. It is
> not something that I have tested under heavy load, so it is quite possible
> that you have uncovered some issue related to this.
> If your stuck images are having a problem related to input event handling,
> then the event handling process would presumably be the one that is running
> and causing the 100% CPU load. You may be able to confirm this with the
> SIGUSR1 trick (below) to dump the Smalltalk stacks to the console output.
> I'm not too familiar with the InputEventFetcher in Pharo, but if the
> inputSemaphore was being signaled by the VM to indicate events available,
> and if for some reason the primitive to retrieve the event was failing,
> then it looks to me like it might loop in that condition with 100% CPU.
> That's a complete wild guess, but something like this may be happening.

Now that I know where the problem lies I might be able to log something meaningful. I'll try to get to the root of the problem. I'd really hate to see others fighting with the same problem when I've already put so much time into it. Hopefully we can create some sort of fix for this.

>> One last question: should this go into OSProcess (I use a older version *cough cough* fo OSProcess and don't know what the changes)?
> I don't think there is anything that I would change in OSProcess at this
> point, I would first want to figure out the underlying cause of the apparent
> event handling problem before changing anything.

You're right of course. I was only speculating.

> If you are using Pharo 2.0 you may want to move to the latest version of
> OSProcess, as I have made a number of updates to make it load cleanly
> in Pharo. Otherwise, I don't think it matters what version of OSProcess
> you are using, as the #forkSqueak behaviour has not changed recently.

I'm on Pharo1.3 but I'll go and check with the latest 2.0 version.


>> Cheers from very rainy Switzerland from a very happy Max :)
> Cheers from Michigan, where the weather has been very nice today for
> a change :)
> Dave

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