September 2020 - Pharo-dev - lists.pharo.org

Re: [Pharo-dev] is there a way to know when a GC is happening?

by Aliaksei Syrel

Hi I wish there was a way to control *when* full GC is allowed to happen. For example, I would prefer GC to occur while the UI rendering loop is paused and not in the middle of the frame resulting in sometimes sluggish animations in the case of large images. Thank you On Wed, 9 Sep 2020 at 14:39, StÃ©phane Ducasse <stephane.ducasse(a)inria.fr> wrote: > Hi > > I would to be able to see when an incremental GC is happening. > is there a way to know when a GC is happening? > > S. > > > -------------------------------------------- > StÃ©phane Ducasse > http://stephane.ducasse.free.fr / http://www.pharo.org > 03 59 35 87 52 > Assistant: Aurore Dalle > FAX 03 59 57 78 50 > TEL 03 59 35 86 16 > S. Ducasse - Inria > 40, avenue Halley > <https://www.google.com/maps/search/40,+avenue+Halley?entry=gmail&source=g> > , > Parc Scientifique de la Haute Borne, BÃ¢t.A, Park Plaza > Villeneuve d'Ascq 59650 > France > > > > > > > > -- Cheers, Alex

Sept. 10, 2020

Re: [Pharo-dev] is there a way to know when a GC is happening?

by Davide Grandi

If Pharo's gc algorithm is concurrent => maybe yes, otherwise surely no : if I'm not wrong gc starts inside VM when checking allocation spaces during a basicNew or alike. And the VM seems stuck, at that moment. One can try to create an ephemeron and check it every 100-500 ms, refreshing it if it's still here (so it will stay in new space). But it shift the question to the definitive target group : the VM guys !!! Chers from Lombardy, Â Â Â Davide (PS : but creating the ephemeron could start an invisible gc !!!) On 09/09/2020 13:38, StÃ©phane Ducasse wrote: > Hi > > I would to be able to see when an incremental GC is happening. > is there a way to know when a GC is happening? > > S. > -------------------------------------------- > StÃ©phane Ducasse > http://stephane.ducasse.free.fr/ http://www.pharo.org > 03 59 35 87 52 > Assistant: Aurore Dalle > FAX 03 59 57 78 50 > TEL 03 59 35 86 16 > S. Ducasse - Inria > 40, avenue Halley, > Parc Scientifique de la Haute Borne, BÃ¢t.A, Park Plaza > Villeneuve d'Ascq 59650 > France > -- Ing. Davide Grandi email : davide.grandi(a)email.it mobile : +39 339 7468 778 linkedin : http://linkedin.com/in/davidegrandi

Sept. 10, 2020

Re: [Pharo-dev] is there a way to know when a GC is happening?

by Martin McClure

On 9/9/20 8:43 PM, Esteban Maringolo wrote: > On Wed, Sep 9, 2020 at 11:58 PM Eliot Miranda <eliot.miranda(a)gmail.com> wrote: > >> In VisualWorks, for example, a WeakArray is primed with an Object instance, and this gets collected every scavenge. >> So the WeakArray is notified. From this VW builds a notification system. > I guess this is how VisualWorks changes its cursor from a regular > pointer to the, sometimes dreadful, "GC" icon during garbage > collection. > Isn't it? > No, that wouldn't work. Notification based on a weak array can only notify after the scavenge (or other GC) has happened, at which point it's too late to put up the GC cursor. And a weak array doesn't seem like it could be reliable for notification of scavenge -- what if the Object in the weak array gets tenured? Then only an incremental or full GC could collect it and notify. Scavenge notification is done by the VM signaling a semaphore that a scavenge notification thread is waiting on. And the GC cursor is simple -- it's explicitly set by Smalltalk code before a compacting GC, and set back afterward. Regards, -Martin

Sept. 10, 2020

Re: [Pharo-dev] is there a way to know when a GC is happening?

by Eliot Miranda

On Wed, Sep 9, 2020 at 9:49 PM Esteban Maringolo <emaringolo(a)gmail.com> wrote: > On Wed, Sep 9, 2020 at 11:58 PM Eliot Miranda <eliot.miranda(a)gmail.com> > wrote: > > > In VisualWorks, for example, a WeakArray is primed with an Object > instance, and this gets collected every scavenge. > > So the WeakArray is notified. From this VW builds a notification system. > > I guess this is how VisualWorks changes its cursor from a regular > pointer to the, sometimes dreadful, "GC" icon during garbage > collection. > Isn't it? > I think so :-) > > Regards! > > Esteban A. Maringolo > and to you, Esteban! _,,,^..^,,,_ best, Eliot

Sept. 10, 2020

Re: [Pharo-dev] is there a way to know when a GC is happening?

by Esteban Maringolo

On Wed, Sep 9, 2020 at 11:58 PM Eliot Miranda <eliot.miranda(a)gmail.com> wrote: > In VisualWorks, for example, a WeakArray is primed with an Object instance, and this gets collected every scavenge. > So the WeakArray is notified. From this VW builds a notification system. I guess this is how VisualWorks changes its cursor from a regular pointer to the, sometimes dreadful, "GC" icon during garbage collection. Isn't it? Regards! Esteban A. Maringolo

Sept. 10, 2020

Re: [Pharo-dev] is there a way to know when a GC is happening?

by Eliot Miranda

On Wed, Sep 9, 2020 at 5:49 AM StÃ©phane Ducasse <stephane.ducasse(a)inria.fr> wrote: > > Hi > > I would to be able to see when an incremental GC is happening. You can't. All GC activity happens while the mutator (the rest of the Smalltalk VM) has stopped executing. i.e. GC does not occur in parallel with the rest of the VM. > is there a way to know when a GC is happening? It is impossible, because effectively GCs happen between sends, and even between bytecodes. But the VM collects statistics that show how many GCs of the various kinds have occurred and how much time has been sent in them The statistics are made available through the vm parameterAt: primitives. They are typically displayed in a SystemReporter dialog. Here's an example from a Squeak image: Virtual Machine Statistics -------------------------- uptime 2d 5h 9m 56s (runtime 10h 27m 28s, idletime 1d 18h 42m 28s) memory 238,690,304 bytes old 229,738,272 bytes (96.2%) young 7,190,528 bytes (3%) used 198,213,464 bytes (83%) free 32,454,736 bytes (13.6%) GCs 110,155 (1737.5 ms between GCs 341.8 ms runtime between GCs) full 115 totalling 17,644 ms (0.05% runtime), avg 153.4 ms marking 6,600 ms (37.4%) avg 57.4 ms, compacting 11,044 ms (62.6%) avg 96 ms scavenges 110,040 totalling 68,213 ms (0.18% runtime), avg 0.6 ms tenures 82,870,154 (avg 753 tenures per scavenge) Code compactions 699 totalling 625 ms (0.002% runtime), avg 0.9 ms These times were collected on a 2.9 GHz Intel Core i9 MacBook Pro. A different question is can one be informed when a GC just happened? The current answer is no, but it would be very easy to add. In VisualWorks, for example, a WeakArray is primed with an Object instance, and this gets collected every scavenge. So the WeakArray is notified. From this VW builds a notification system. I would engineer it differently. If there is a Semaphore in either of two slots in the specialObjectsArray the VM could signal one Semaphore whenever a scavenge occurs and signal the other when a full GC occurs. P.S> can we please stop using the term "incremental GC" for a young space collection? In Spur the young space GC is a classic Ungar-style scavenger, so I like to call these GCs scavenges. Soon I hope that the Spur VM will have a proper incremental global GC. This will comprise a mark-sweep collector and a compactor fort old space, but both will operate incrementally. The mark phase will be done in increments, allowing very small pause times as marking proceeds. Likewise sweeping to free objects and especially compacting, to coalesce storage, will be done in small increments. So there will be pause times of the order of 2 or 3 millisecondes due to the incremental collector and overall the system will avoid the relatively long pauses the global GC causes. HTH _,,,^..^,,,_ best, Eliot

Sept. 10, 2020

[Pharo 9.0] Build #652: SystemHelp-no-PragmaCollector

by ci-pharo-ci-jenkins2＠inria.fr

There is a new Pharo build available! The status of the build #652 was: FAILURE. The Pull Request #7275 was integrated: "SystemHelp-no-PragmaCollector" Pull request url: https://github.com/pharo-project/pharo/pull/7275 Issue Url: https://github.com/pharo-project/pharo/issues/SystemHelp Build Url: https://ci.inria.fr/pharo-ci-jenkins2/job/Test%20pending%20pull%20request%2…

Sept. 9, 2020

[Pharo 9.0] Build #651: Variables-variable-not-binding

by ci-pharo-ci-jenkins2＠inria.fr

There is a new Pharo build available! The status of the build #651 was: FAILURE. The Pull Request #7280 was integrated: "Variables-variable-not-binding" Pull request url: https://github.com/pharo-project/pharo/pull/7280 Issue Url: https://github.com/pharo-project/pharo/issues/Variables Build Url: https://ci.inria.fr/pharo-ci-jenkins2/job/Test%20pending%20pull%20request%2…

Sept. 9, 2020

Re: [Pharo-dev] sideOf: logic

by tbrunz

It just occurred to me: If you have a graphic element, such as a triangle or rectangle, etc., and you want to know if a point lies inside it or outside it, you would want a method such as this one. But I think you would need to apply it relative to a vertex of the polygon in question, since it assumes a ray starting at (0@0) to a given point (i.e., an adjoining vertex). -- Sent from: http://forum.world.st/Pharo-Smalltalk-Developers-f1294837.html

Sept. 9, 2020

Re: [Pharo-dev] sideOf: logic

by tbrunz

I'm not sure, but I suspect this is a helpful method for things in analytic geometry. I.e., if you have a ray and a point, it would allow you to determine the direction to move for the shortest path (in polar coordinates, for example). -t -- Sent from: http://forum.world.st/Pharo-Smalltalk-Developers-f1294837.html

Sept. 9, 2020