If a process is running when an image is saved, is the process stopped at
any point in particular? If the saved image is started, is there any way the process can tell? I'm running a process that keeps running for a look time. It loops with a delay and in the loop gets the date and time. If the date and time were obtained just before the save, they would be old at the time of the image restart and need to be refreshed. Lou ----------------------------------------------------------- Louis LaBrunda Keystone Software Corp. SkypeMe callto://PhotonDemon mailto:[hidden email] http://www.Keystone-Software.com |
On 2013-02-28, at 22:38, Louis LaBrunda <[hidden email]> wrote:
> If a process is running when an image is saved, is the process stopped at > any point in particular? The active process is stopped in the snapshot primitive (a.k.a. "image saving") and resumes after it on startup. All other processes are waiting on some semaphore anyway. > If the saved image is started, is there any way the process can tell? Not the process itself. But you surely keep the process in a class somewhere, and the class can arrange to get notified on startup by adding itself to the startup list. See addToStartUpList:. > I'm running a process that keeps running for a look time. It loops with a > delay and in the loop gets the date and time. If the date and time were > obtained just before the save, they would be old at the time of the image > restart and need to be refreshed. Delays get adjusted after resuming from snapshot. So it should just work. - Bert - |
In reply to this post by Louis LaBrunda
Hi Lou, See: SmalltalkImage >> snapshot: save andQuit: quit embedded: embeddedFlag What you are looking for is #startUp. Register your class with: Smalltalk addToStartUpList: self Or: Smalltalk addToStartUpList: self after: CPlatform. “this is an example, but if you have a particular order this is useful” You can remove your class with: Smalltalk removeFromStartUpList: self. Then you just need to implement the #startUp method on your class to handle refreshing the date. Hope that helps. All the best, Ron Teitelbaum Head Of Engineering 3d Immersive Collaboration Consulting Follow Me On Twitter: @RonTeitelbaum > -----Original Message----- > From: [hidden email] [mailto:squeak-dev- > [hidden email]] On Behalf Of Louis LaBrunda > Sent: Thursday, February 28, 2013 4:38 PM > To: [hidden email] > Subject: [squeak-dev] Running process after image save/stop/restart > > If a process is running when an image is saved, is the process stopped at any > point in particular? > > If the saved image is started, is there any way the process can tell? > > I'm running a process that keeps running for a look time. It loops with a delay > and in the loop gets the date and time. If the date and time were obtained just > before the save, they would be old at the time of the image restart and need to > be refreshed. > > > Lou > ----------------------------------------------------------- > Louis LaBrunda > Keystone Software Corp. > SkypeMe <a href="callto://PhotonDemon">callto://PhotonDemon > [hidden email] http://www.Keystone-Software.com > > |
Hi Ron,
Thanks for the help. >Then you just need to implement the #startUp method on your class to handle >refreshing the date. Is #startUp a class side method? When I try to save it, I get an ominous warning message. Lou ----------------------------------------------------------- Louis LaBrunda Keystone Software Corp. SkypeMe callto://PhotonDemon mailto:[hidden email] http://www.Keystone-Software.com |
Hi Lou, Yes see: processStartUpList: resuming "Send #startUp to each class that needs to run initialization after a snapshot." self send: #startUp: toClassesNamedIn: StartUpList with: resuming. If you need to send to instances then have the class side do it. MyClass class >> startUp: resuming "Send startUp to all my instances self allInstnaces do: [:a | a startUp: resuming]. Or maybe, “send startUp to my default instance” Default ifNotNil: [Default startUp: resuming]. Hope that helps. All the best, Ron Teitelbaum Head Of Engineering 3d Immersive Collaboration Consulting Follow Me On Twitter: @RonTeitelbaum > -----Original Message----- > From: [hidden email] [mailto:squeak-dev- > [hidden email]] On Behalf Of Louis LaBrunda > Sent: Thursday, February 28, 2013 6:37 PM > To: [hidden email] > Subject: [squeak-dev] Running process after image save/stop/restart > > Hi Ron, > > Thanks for the help. > > >Then you just need to implement the #startUp method on your class to > >handle refreshing the date. > > Is #startUp a class side method? When I try to save it, I get an ominous warning > message. > > Lou > ----------------------------------------------------------- > Louis LaBrunda > Keystone Software Corp. > SkypeMe <a href="callto://PhotonDemon">callto://PhotonDemon > [hidden email] http://www.Keystone-Software.com > > |
In reply to this post by Bert Freudenberg
Hi Bert,
Thanks for the help. I was trying to solve a problem adjusting things after an image restart and got into the weeds with fixing variables holding what should be the current date and time. That fix could have had a timing problem with when the image was saved. As it turns out adding a #startUp class method allows me to easily fix things without concern for dates and time and where the code was when the image was saved. Lou On Thu, 28 Feb 2013 23:30:08 +0100, Bert Freudenberg <[hidden email]> wrote: >On 2013-02-28, at 22:38, Louis LaBrunda <[hidden email]> wrote: > >> If a process is running when an image is saved, is the process stopped at >> any point in particular? > >The active process is stopped in the snapshot primitive (a.k.a. "image saving") and resumes after it on startup. All other processes are waiting on some semaphore anyway. > >> If the saved image is started, is there any way the process can tell? > >Not the process itself. But you surely keep the process in a class somewhere, and the class can arrange to get notified on startup by adding itself to the startup list. See addToStartUpList:. > >> I'm running a process that keeps running for a look time. It loops with a >> delay and in the loop gets the date and time. If the date and time were >> obtained just before the save, they would be old at the time of the image >> restart and need to be refreshed. > > >Delays get adjusted after resuming from snapshot. So it should just work. > >- Bert - > > Louis LaBrunda Keystone Software Corp. SkypeMe callto://PhotonDemon mailto:[hidden email] http://www.Keystone-Software.com |
In reply to this post by Ron Teitelbaum
Hi Ron,
Thanks again. I thought the #startUp method needed to be on the class side but as I said the ominous warning message on saving it scared me a little. I did need to do some work on the instance side but that was easy. Lou On Thu, 28 Feb 2013 19:59:33 -0500, "Ron Teitelbaum" <[hidden email]> wrote: >Hi Lou, >Yes see: >processStartUpList: resuming > > "Send #startUp to each class that needs to run initialization >after a snapshot." > self send: #startUp: toClassesNamedIn: StartUpList with: >resuming. >If you need to send to instances then have the class side do it. >MyClass class >> startUp: resuming > "Send startUp to all my instances > > self allInstnaces do: [:a | a startUp: resuming]. >Or maybe, > "send startUp to my default instance" > > Default ifNotNil: [Default startUp: resuming]. >Hope that helps. >All the best, >Ron Teitelbaum > >Head Of Engineering > >3d Immersive Collaboration Consulting > >[hidden email] > >Follow Me On Twitter: @RonTeitelbaum <https://twitter.com/RonTeitelbaum> > >www.3dicc.com <http://www.3dicc.com/> > >3d ICC on G+ ><https://plus.google.com/u/0/b/108936249366287171125/108936249366287171125/p >osts> > > > > > > > >> -----Original Message----- > >> From: [hidden email] [mailto:squeak-dev- > >> [hidden email]] On Behalf Of Louis LaBrunda > >> Sent: Thursday, February 28, 2013 6:37 PM > >> To: [hidden email] > >> Subject: [squeak-dev] Running process after image save/stop/restart > >> > >> Hi Ron, > >> > >> Thanks for the help. > >> > >> >Then you just need to implement the #startUp method on your class to > >> >handle refreshing the date. > >> > >> Is #startUp a class side method? When I try to save it, I get an ominous >warning > >> message. > >> > >> Lou > >> ----------------------------------------------------------- > >> Louis LaBrunda > >> Keystone Software Corp. > >> SkypeMe <callto://PhotonDemon> callto://PhotonDemon > >> <mailto:[hidden email]> mailto:[hidden email] ><http://www.Keystone-Software.com> http://www.Keystone-Software.com > >> > >> > > Louis LaBrunda Keystone Software Corp. SkypeMe callto://PhotonDemon mailto:[hidden email] http://www.Keystone-Software.com |
Hi Lou,
You are welcome! Glad it worked! Ron > From: [hidden email] [mailto:squeak-dev- > [hidden email]] On Behalf Of Louis LaBrunda > > Hi Ron, > > Thanks again. I thought the #startUp method needed to be on the class side but > as I said the ominous warning message on saving it scared me a little. > I did need to do some work on the instance side but that was easy. > > Lou > > On Thu, 28 Feb 2013 19:59:33 -0500, "Ron Teitelbaum" <[hidden email]> > wrote: > > >Hi Lou, > >Yes see: > >processStartUpList: resuming > > > > "Send #startUp to each class that needs to run > >initialization after a snapshot." > > self send: #startUp: toClassesNamedIn: StartUpList with: > >resuming. > >If you need to send to instances then have the class side do it. > >MyClass class >> startUp: resuming > > "Send startUp to all my instances > > > > self allInstnaces do: [:a | a startUp: resuming]. > >Or maybe, > > "send startUp to my default instance" > > > > Default ifNotNil: [Default startUp: resuming]. > >Hope that helps. > >All the best, > >Ron Teitelbaum > > > >Head Of Engineering > > > >3d Immersive Collaboration Consulting > > > >[hidden email] > > > >Follow Me On Twitter: @RonTeitelbaum > ><https://twitter.com/RonTeitelbaum> > > > >www.3dicc.com <http://www.3dicc.com/> > > > >3d ICC on G+ > ><https://plus.google.com/u/0/b/108936249366287171125/108936249366287 > 171 > >125/p > >osts> > > > > > > > > > > > > > > > >> -----Original Message----- > > > >> From: [hidden email] > >> [mailto:squeak-dev- > > > >> [hidden email]] On Behalf Of Louis LaBrunda > > > >> Sent: Thursday, February 28, 2013 6:37 PM > > > >> To: [hidden email] > > > >> Subject: [squeak-dev] Running process after image save/stop/restart > > > >> > > > >> Hi Ron, > > > >> > > > >> Thanks for the help. > > > >> > > > >> >Then you just need to implement the #startUp method on your class to > > > >> >handle refreshing the date. > > > >> > > > >> Is #startUp a class side method? When I try to save it, I get an > >> ominous > >warning > > > >> message. > > > >> > > > >> Lou > > > >> ----------------------------------------------------------- > > > >> Louis LaBrunda > > > >> Keystone Software Corp. > > > >> SkypeMe <callto://PhotonDemon> callto://PhotonDemon > > > >> <mailto:[hidden email]> mailto:Lou@Keystone- > Software.com > ><http://www.Keystone-Software.com> http://www.Keystone-Software.com > > > >> > > > >> > > > > > ----------------------------------------------------------- > Louis LaBrunda > Keystone Software Corp. > SkypeMe callto://PhotonDemon > mailto:[hidden email] http://www.Keystone-Software.com > > |
In reply to this post by Bert Freudenberg
On Thu, Feb 28, 2013 at 2:30 PM, Bert Freudenberg <[hidden email]> wrote: --
Nope. No processes are stopped. Processes are simply unable to run while in the snapshot. The key to understanding this is understanding the scheduler (the Processor global, an instance of ProcessorSheduler). It maintains an activeProcess and a set of runnable processes, implemented as an Array of lists of processes at the same priority. A runnable process (one not sent suspend or not waiting on a semaphore) is either the activeProcess or on one of the lists. This state is saved to the snapshot. At any time the scheduler's activeProcess is the first highest priority process in the set of runnable processes. It will only be deposed as activeProcess when either another higher-priority process becomes runnable or it yields or suspends or waits on a semaphore. If it suspends or waits on a semaphore it is removed from the set of runnable processes. If it yields it gets sent to the back of its run-queue and the next process in that queue becomes the runnable process. If it is the only runnable process at its priority yield is a noop.
On loading the image the VM activates the activeProcess; the activeProcess will typically be in a method that has called the snapshot primitive and the system will continue, with the snapshot primitive answering true. All the other processes in the run queues are runnable but, just as before the snapshot, can't be run because the activeProcess is still runnable. But as soon as the activeProcess suspends, waits or yields, one of these processes may run.
Several processes are terminated (terminate is suspend + run unwinds) on resuming the image. This is done to inform the VM of additional state to make these processes run. For example, the Delay process needs to tell the VM what the next delay expiry is on start-up. The delay semaphore (the semaphore the VM signals when the current active delay expires) is saved in the image in the specialObjects array, so it persists across a snapshot, but the VM doesn't persist the current delay expiry time.
So any long-running process which doesn't need to inform the VM of anything special at start-up will just keep truckin' along, and nothing need be done. A snapshot really is like a fermata, a pause. It is not some kind of shut-down.
As a side-note what happens if one does [Semaphore new wait] fork. Processor activeProcess yield. ? This creates a new process and adds it to the Processor's run queue. Once the process has been sent fork the current process doesn't reference it since it has been popped from the current process's stack, and so the only reference to the new process is from one of the Processors' run queues, but it isn't running yet because the activeProcess (the one that sent fork) is running. Wen the activeProcess yields the new process gets to run. Once it has created the new semaphore it sends wait to it. At this point it is removed from the Processor's run-queue and added to the semaphore's queue. So now there is a circular reference between the process and the semaphore and these are the only references to the process and the semaphore, and so both get garbage collected.
exactly. one could also e.g. poll OSProcess to get the process ID of the VM process and see if that changes, but that's a horrible hack, and once in a blue moon will fail (cuz process ids are not unique and get reused).
exactly. the snapshot will look just like a long time on the run-queue whole the process is preempted by higher-priroity processes,
- Bert - HTH, Eliot
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On 2013-03-05, at 21:32, Eliot Miranda <[hidden email]> wrote:
Yes, I used sloppy language, "suspended" is loaded in this context. The active process does not go through a suspend/resume cycle, it's simply that time "stops" and later "continues", so to speak. Excellent explanation, Eliot :) - Bert -
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In reply to this post by Eliot Miranda-2
Hi Eliot,
Thanks for all the very valuable information. I think I didn't ask my question properly but with all the answers I was able to accomplish exactly what I wanted. I do have a question about one thing you said. See below. Lou >On Thu, Feb 28, 2013 at 2:30 PM, Bert Freudenberg <[hidden email]>wrote: > >> On 2013-02-28, at 22:38, Louis LaBrunda <[hidden email]> wrote: >> >> > If a process is running when an image is saved, is the process stopped at >> > any point in particular? >> >> The active process is stopped in the snapshot primitive (a.k.a. "image >> saving") and resumes after it on startup. All other processes are waiting >> on some semaphore anyway. >> > >Nope. No processes are stopped. Processes are simply unable to run while >in the snapshot. The key to understanding this is understanding the >scheduler (the Processor global, an instance of ProcessorSheduler). It >maintains an activeProcess and a set of runnable processes, implemented as >an Array of lists of processes at the same priority. A runnable process >(one not sent suspend or not waiting on a semaphore) is either the >activeProcess or on one of the lists. This state is saved to the snapshot. > At any time the scheduler's activeProcess is the first highest priority >process in the set of runnable processes. It will only be deposed as >activeProcess when either another higher-priority process becomes runnable >or it yields or suspends or waits on a semaphore. If it suspends or waits >on a semaphore it is removed from the set of runnable processes. If it >yields it gets sent to the back of its run-queue and the next process in >that queue becomes the runnable process. If it is the only runnable >process at its priority yield is a noop. > >On loading the image the VM activates the activeProcess; the activeProcess >will typically be in a method that has called the snapshot primitive and >the system will continue, with the snapshot primitive answering true. All >the other processes in the run queues are runnable but, just as before the >snapshot, can't be run because the activeProcess is still runnable. But as >soon as the activeProcess suspends, waits or yields, one of these processes >may run. > >Several processes are terminated (terminate is suspend + run unwinds) on >resuming the image. This is done to inform the VM of additional state to >make these processes run. For example, the Delay process needs to tell the >VM what the next delay expiry is on start-up. The delay semaphore (the >semaphore the VM signals when the current active delay expires) is saved in >the image in the specialObjects array, so it persists across a snapshot, >but the VM doesn't persist the current delay expiry time. > >So any long-running process which doesn't need to inform the VM of anything >special at start-up will just keep truckin' along, and nothing need be >done. A snapshot really is like a fermata, a pause. It is not some kind >of shut-down. > >As a side-note what happens if one does > > [Semaphore new wait] fork. > Processor activeProcess yield. > >? > >This creates a new process and adds it to the Processor's run queue. Once >the process has been sent fork the current process doesn't reference it >since it has been popped from the current process's stack, and so the only >reference to the new process is from one of the Processors' run queues, but >it isn't running yet because the activeProcess (the one that sent fork) is >running. When the activeProcess yields the new process gets to run. Once >it has created the new semaphore it sends wait to it. At this point it is >removed from the Processor's run-queue and added to the semaphore's queue. > So now there is a circular reference between the process and the semaphore >and these are the only references to the process and the semaphore, and so >both get garbage collected. I think the forked process gets to run before the processor returns to the yield line. This is the way it works in VA Smalltalk and from looking at the implementers of #fork, I think it is the way it works in Squeak. I could be wrong, if so please be kind, I have been following the news group for a while but I'm new to playing with Squeak. There were times when I wanted to create a new fork but didn't want it to run until the method creating it finished. So, I added #forkReady (and friends) that would create the process but not run it right away. >> >> > If the saved image is started, is there any way the process can tell? >> >> Not the process itself. But you surely keep the process in a class >> somewhere, and the class can arrange to get notified on startup by adding >> itself to the startup list. See addToStartUpList:. >> > >exactly. one could also e.g. poll OSProcess to get the process ID of the VM >process and see if that changes, but that's a horrible hack, and once in a >blue moon will fail (cuz process ids are not unique and get reused). > >> I'm running a process that keeps running for a look time. It loops with a >> > delay and in the loop gets the date and time. If the date and time were >> > obtained just before the save, they would be old at the time of the image >> > restart and need to be refreshed. >> >> >> Delays get adjusted after resuming from snapshot. So it should just work. >> > >exactly. the snapshot will look just like a long time on the run-queue >whole the process is preempted by higher-priroity processes, > > >> - Bert - >> Louis LaBrunda Keystone Software Corp. SkypeMe callto://PhotonDemon mailto:[hidden email] http://www.Keystone-Software.com |
On Tue, Mar 5, 2013 at 1:36 PM, Louis LaBrunda <[hidden email]> wrote: Hi Eliot, No. In Smalltalk-80 (VisualWorks, Squeak etc) fork creates a new process with the same priority as the current process and then resumes it (resume is the primitive that adds the process to the run queue). So the new process is effectively behind the activeProcess in the run-queue. e.g.
| who | who := #me. [who := #him. Semaphore new wait] fork. who => #me | who | who := #me. [who := #him. Semaphore new wait] fork.
Processor yield. who => #him I can't speak for VA, but I doubt you;re right. I expect VA to have the same behaviour as the above. There were times when I wanted to create a new fork but didn't want it to there's also forkAt: Processor activePriority - 1, or | gate result | gate := Semaphore new.
[gate wait. self doStuff] fork. result := self getResult. gate signal. ^result
best, Eliot
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In reply to this post by Bert Freudenberg
On Tue, Mar 5, 2013 at 1:21 PM, Bert Freudenberg <[hidden email]> wrote:
That's OK. I was correcting "All other processes are waiting on some semaphore anyway.". That's definitely not the case. Forgive my pedantry.
Tuesday OCD ;)
best, Eliot
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In reply to this post by Eliot Miranda-2
I will bow to your knowledge of Squeak but take a look at the code below
from VA Smalltalk. Pay special attention to #resume: which looks to me like it puts the new process at the top of the queue (there are 7 queues, one for each priority) and puts the current (activeProcess) at the bottom of the same queue and then switches to the highestPriorityProcess. Which can be another process or the new process just put in front of the current process. Don't ask my why it works this way. As I said, I added #forkReady which it seems works more like Squeak. Most of the time I think it doesn't matter but sometimes it does. Lou fork "Create a new Process which is scheduled by the ProcessScheduler. The new process executes the receiver by sending it the message value. The new process is created with the same prority as the activeProcess. Answer the receiver." ^self newProcess resume resume "Tell the process scheduler to add the process to the ready to run queue." self isResumable ifFalse: [^self error: (NlsCatKRN indexedMsg: 2)]. "$NLS$ process cannot be resumed" Processor resume: self. ^ self resume: aProcess | state | state := self enableAsyncMessages: false. (aProcess == self activeProcess or: [aProcess isDead]) ifTrue: [ self enableAsyncMessages: state. ^self "Resuming a dead process or the active process is a nop."]. aProcess isRunable ifTrue: [ (aProcess processState: ##ready) queue addFirst: aProcess]. (self activeProcess processState: ##ready) queue addLast: self activeProcess. self activeProcess switchTo: self highestPriorityProcess. self enableAsyncMessages: state On Tue, 5 Mar 2013 13:46:13 -0800, Eliot Miranda <[hidden email]> wrote: >On Tue, Mar 5, 2013 at 1:36 PM, Louis LaBrunda <[hidden email]>wrote: > >> Hi Eliot, >> >> Thanks for all the very valuable information. I think I didn't ask my >> question properly but with all the answers I was able to accomplish exactly >> what I wanted. >> >> I do have a question about one thing you said. See below. >> >> Lou >> >> >On Thu, Feb 28, 2013 at 2:30 PM, Bert Freudenberg <[hidden email] >> >wrote: >> > >> >> On 2013-02-28, at 22:38, Louis LaBrunda <[hidden email]> >> wrote: >> >> >> >> > If a process is running when an image is saved, is the process >> stopped at >> >> > any point in particular? >> >> >> >> The active process is stopped in the snapshot primitive (a.k.a. "image >> >> saving") and resumes after it on startup. All other processes are >> waiting >> >> on some semaphore anyway. >> >> >> > >> >Nope. No processes are stopped. Processes are simply unable to run while >> >in the snapshot. The key to understanding this is understanding the >> >scheduler (the Processor global, an instance of ProcessorSheduler). It >> >maintains an activeProcess and a set of runnable processes, implemented as >> >an Array of lists of processes at the same priority. A runnable process >> >(one not sent suspend or not waiting on a semaphore) is either the >> >activeProcess or on one of the lists. This state is saved to the >> snapshot. >> > At any time the scheduler's activeProcess is the first highest priority >> >process in the set of runnable processes. It will only be deposed as >> >activeProcess when either another higher-priority process becomes runnable >> >or it yields or suspends or waits on a semaphore. If it suspends or waits >> >on a semaphore it is removed from the set of runnable processes. If it >> >yields it gets sent to the back of its run-queue and the next process in >> >that queue becomes the runnable process. If it is the only runnable >> >process at its priority yield is a noop. >> > >> >On loading the image the VM activates the activeProcess; the activeProcess >> >will typically be in a method that has called the snapshot primitive and >> >the system will continue, with the snapshot primitive answering true. All >> >the other processes in the run queues are runnable but, just as before the >> >snapshot, can't be run because the activeProcess is still runnable. But >> as >> >soon as the activeProcess suspends, waits or yields, one of these >> processes >> >may run. >> > >> >Several processes are terminated (terminate is suspend + run unwinds) on >> >resuming the image. This is done to inform the VM of additional state to >> >make these processes run. For example, the Delay process needs to tell >> the >> >VM what the next delay expiry is on start-up. The delay semaphore (the >> >semaphore the VM signals when the current active delay expires) is saved >> in >> >the image in the specialObjects array, so it persists across a snapshot, >> >but the VM doesn't persist the current delay expiry time. >> > >> >So any long-running process which doesn't need to inform the VM of >> anything >> >special at start-up will just keep truckin' along, and nothing need be >> >done. A snapshot really is like a fermata, a pause. It is not some kind >> >of shut-down. >> > >> >As a side-note what happens if one does >> > >> > [Semaphore new wait] fork. >> > Processor activeProcess yield. >> > >> >? >> > >> >This creates a new process and adds it to the Processor's run queue. Once >> >the process has been sent fork the current process doesn't reference it >> >since it has been popped from the current process's stack, and so the only >> >reference to the new process is from one of the Processors' run queues, >> but >> >it isn't running yet because the activeProcess (the one that sent fork) is >> >running. When the activeProcess yields the new process gets to run. Once >> >it has created the new semaphore it sends wait to it. At this point it is >> >removed from the Processor's run-queue and added to the semaphore's queue. >> > So now there is a circular reference between the process and the >> semaphore >> >and these are the only references to the process and the semaphore, and so >> >both get garbage collected. >> >> I think the forked process gets to run before the processor returns to the >> yield line. This is the way it works in VA Smalltalk and from looking at >> the implementers of #fork, I think it is the way it works in Squeak. I >> could be wrong, if so please be kind, I have been following the news group >> for a while but I'm new to playing with Squeak. >> > >No. In Smalltalk-80 (VisualWorks, Squeak etc) fork creates a new process >with the same priority as the current process and then resumes it (resume >is the primitive that adds the process to the run queue). So the new >process is effectively behind the activeProcess in the run-queue. e.g. > >| who | >who := #me. >[who := #him. Semaphore new wait] fork. >who >=> #me > > >| who | >who := #me. >[who := #him. Semaphore new wait] fork. >Processor yield. >who >=> #him > >I can't speak for VA, but I doubt you;re right. I expect VA to have the >same behaviour as the above. > > > >> There were times when I wanted to create a new fork but didn't want it to >> run until the method creating it finished. So, I added #forkReady (and >> friends) that would create the process but not run it right away. >> > >there's also forkAt: Processor activePriority - 1, or > >| gate result | >gate := Semaphore new. >[gate wait. > self doStuff] fork. >result := self getResult. >gate signal. >^result > > >> >> >> >> > If the saved image is started, is there any way the process can tell? >> >> >> >> Not the process itself. But you surely keep the process in a class >> >> somewhere, and the class can arrange to get notified on startup by >> adding >> >> itself to the startup list. See addToStartUpList:. >> >> >> > >> >exactly. one could also e.g. poll OSProcess to get the process ID of the >> VM >> >process and see if that changes, but that's a horrible hack, and once in a >> >blue moon will fail (cuz process ids are not unique and get reused). >> > >> >> I'm running a process that keeps running for a look time. It loops >> with a >> >> > delay and in the loop gets the date and time. If the date and time >> were >> >> > obtained just before the save, they would be old at the time of the >> image >> >> > restart and need to be refreshed. >> >> >> >> >> >> Delays get adjusted after resuming from snapshot. So it should just >> work. >> >> >> > >> >exactly. the snapshot will look just like a long time on the run-queue >> >whole the process is preempted by higher-priroity processes, >> > >> > >> >> - Bert - >> >> >> ----------------------------------------------------------- >> Louis LaBrunda >> Keystone Software Corp. >> SkypeMe callto://PhotonDemon >> mailto:[hidden email] http://www.Keystone-Software.com >> >> >> Louis LaBrunda Keystone Software Corp. SkypeMe callto://PhotonDemon mailto:[hidden email] http://www.Keystone-Software.com |
Hi Lou,
On Tue, Mar 5, 2013 at 2:38 PM, Louis LaBrunda <[hidden email]> wrote: I will bow to your knowledge of Squeak but take a look at the code below thanks, that's interesting, and good to know.
best, Eliot
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