Smalltalk › Cincom › VisualWorks

[vwnc] SocketAccessor>>accept blocks image?

_‹ Previous Topic Next Topic _›

Classic

List

Threaded

5 messages Options

kobetic

[vwnc] SocketAccessor>>accept blocks image?

"Philippe Demaecker"<[hidden email]> wrote:
> 3. Below you can find 2 stack traces created by a ctrl-y at a moment the image was blocking.
> Stack 1: it seems that SocketAccessor>>primAccept runs into an (EWouldBlock) error trying to report it, but blocking the image.

What exactly do you mean by "blocking the image" ? Socket operations shouldn't be blocking the VM, i.e. only the process performing the socket operation should be blocked, any other runnable processes should be able to run as long as they get Processor time. Is something spinning at a high priority ? The listener process normally does run at an elevated priority.

> Stack 2: the proxy setting up its listener process
>
> So, I have a few questions:
>
> 1. Why is the proxy starting a listener process? I don't understand we this is necessary when communication between Client and server happens using the sendRequest:? What am I missing?

The client uses an Opentalk broker and currently there is no way to start a broker without an active listener. Yes it is not necessary and wasteful in a client only configuration but that's what it is atm.

> 2. How can I create a situation where primAccept would return a EWOULDBLOCK error?

Not sure about that. It likely depends on specifics of your platform. Can you provide more details about that ?

> 3. Why is raising a EWOULDBLOCK in primAccept blocking the image?

As I said, socket operations don't block the whole image, just the process performing them. My guess is that the listener process ended up spinning at a high priority and consequently starving all other lower priority processes (including any UI processes). You can try setting the listenerPriority: below 50 and see if it makes any difference.

HTH,

Martin
_______________________________________________
vwnc mailing list
[hidden email]
http://lists.cs.uiuc.edu/mailman/listinfo/vwnc

Philippe Demaecker

Re: [vwnc] SocketAccessor>>accept blocks image?

Hello Martin,

Thanks for replying.
1. The listener is running at prio 83, lowering this value does not seem to change anything.

2. It's running VW 7.4.1 on Windows, I will ask for more detailed information about the CPU and Windows version.

3. Blocking image = all VW windows are grey and unresponsive (you can try for yourself using the scenario from my original mail).

You CAN still ctrl-y though, ending up in

[1] OsNeedRetryError(GenericException)>>findHandlerContextFrom:markDebug:
[2] OsNeedRetryError(GenericException)>>propagatePrivateFrom:
[3] OsNeedRetryError(GenericException)>>propagateFrom:
[4] OsNeedRetryError(GenericException)>>propagate
[5] OsNeedRetryError(GenericException)>>raiseRequest
[6] HandleRegistry>>evaluateWithFullProtection:
[7] HandleRegistry>>registerValueOf:
[8] SocketAccessor class(OSHandle class)>>handleValue:
[9] SocketAccessor>>accept
[10] optimized [] in Opentalk.ConnectionListener>>listenerProcessBody

. It seem that, once primAccept has been raised, that evaluateWithFullProtection: does not seem to be able to propagate this exception further...

. Also, is there any reason a connection would be made to the server process of the proxy?

Thanks for your help!
Philippe

> 3. Below you can find 2 stack traces created by a ctrl-y at a moment the image was blocking.
> Stack 1: it seems that SocketAccessor>>primAccept runs into an (EWouldBlock) error trying to report it, but blocking the image.

What exactly do you mean by "blocking the image" ? Socket operations shouldn't be blocking the VM, i.e. only the process performing the socket operation should be blocked, any other runnable processes should be able to run as long as they get Processor time. Is something spinning at a high priority ? The listener process normally does run at an elevated priority.

> 2. How can I create a situation where primAccept would return a EWOULDBLOCK error?

Not sure about that. It likely depends on specifics of your platform. Can you provide more details about that ?

> 3. Why is raising a EWOULDBLOCK in primAccept blocking the image?

As I said, socket operations don't block the whole image, just the process performing them. My guess is that the listener process ended up spinning at a high priority and consequently starving all other lower priority processes (including any UI processes). You can try setting the listenerPriority: below 50 and see if it makes any difference.

HTH,

Martin

_______________________________________________
vwnc mailing list
[hidden email]
http://lists.cs.uiuc.edu/mailman/listinfo/vwnc

WSOpentalkTestClient.st (2K) Download Attachment