Hi Stefan,
this sounds a lot like an issue that bit someone in squeak 4.x recently and was due to a bytecode compiler bug that I fixed. I can't find or remember the email associated with this, so if anyone does remember please speak up. Stefan, you might try running this in an updated squeak 4.1 image and compare the bytecodes. If you get different bytecodes then we need to port the compiler fixes from 4.1 trunk to Pharo.
HTH Eliot
On Wed, Sep 29, 2010 at 10:22 AM, Stefan Marr pharo@stefan-marr.de wrote:
Further testing reveals a strange behavior in the debugger. So, I am not sure where the problem is actually caused.
I added a new local variable block to the method. block gets assigned aBlock (the parameter).
If I executed Erlang spawn: [Transcript show: 'foo'], the '1 halt.' is executed as I mentioned before. However, the debugger does not allow me to access aBlock, there is a subscript out of bound exception. Interestingly, 'block' is accessible without error.
If I now actually use 'block' instead of 'aBlock' in the executed block, then phenomena is reversed. Thus, the variable which is actually referenced in the code is not accessible anymore but gets somehow lost. They also get lost if I use both.
I would still like to understand what is going on here. So any remarks are welcome.
Thanks Stefan
spawn: aBlock "Answer an ErlProcess running the code given in the parameter. The process isscheduled." | proc block | <primitive: 19> "Simulation guard" block := aBlock. proc := Process forContext: [1 halt. aBlock value. Processor terminateActive] asContext priority: Processor activePriority. proc resume. ^ proc
On 29 Sep 2010, at 11:21, Stefan Marr wrote:
On 29 Sep 2010, at 11:01, Igor Stasenko wrote:
On 29 September 2010 11:11, Stéphane Ducasse stephane.ducasse@inria.fr
wrote:
no idea but I want to know that too so keep us posted.
Smalltalk specialObjectsArray at: 28. Thats it, Process is a special object, recognized by VM. No other Process (sub)classes can be accepted by it.
Could you elaborate on that? No other process can be accepted for what? Being scheduled, or being executed?
There is also a comment in the comment of Process which suggests that it
should be possible:
"(If anyone ever makes a subclass of Process, be sure to use
allSubInstances in anyProcessesAbove:.)"
But even after making the change, that does not seem to be the actual
problem.
The process gets execute fine. With a '1 halt.' as the first statement of
the aBlock block I even get a debugger. It only fails on accessing variables referenced by the closure with an index out of bound error or something similar.
Erlang>>spawn: aBlock "Answer an ErlProcess running the code given in the parameter. The process is scheduled." | proc | proc := ErlProcess forContext: [1 halt. aBlock value. Processor terminateActive] asContext priority: Processor activePriority. proc resume. ^ proc
Thanks and best regards Stefan
-- Stefan Marr Software Languages Lab Vrije Universiteit Brussel Pleinlaan 2 / B-1050 Brussels / Belgium http://soft.vub.ac.be/~smarr Phone: +32 2 629 2974 Fax: +32 2 629 3525
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
-- Stefan Marr Software Languages Lab Vrije Universiteit Brussel Pleinlaan 2 / B-1050 Brussels / Belgium http://soft.vub.ac.be/~smarr Phone: +32 2 629 2974 Fax: +32 2 629 3525
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
Hi Eliot:
I had tried Squeak 4.1 before, also updated, but same result.
However, after your mail I tried an updated Squeak 4.2 alpha (http://ftp.squeak.org/trunk/Squeak4.2-10382-alpha.zip) and here it works.
Thanks for the hint.
Best regards Stefan
On 29 Sep 2010, at 19:48, Eliot Miranda wrote:
Hi Stefan,
this sounds a lot like an issue that bit someone in squeak 4.x recently and was due to a bytecode compiler bug that I fixed. I can't find or remember the email associated with this, so if anyone does remember please speak up. Stefan, you might try running this in an updated squeak 4.1 image and compare the bytecodes. If you get different bytecodes then we need to port the compiler fixes from 4.1 trunk to Pharo.HTH Eliot
On Wed, Sep 29, 2010 at 10:22 AM, Stefan Marr pharo@stefan-marr.de wrote: Further testing reveals a strange behavior in the debugger. So, I am not sure where the problem is actually caused.
I added a new local variable block to the method. block gets assigned aBlock (the parameter).
If I executed Erlang spawn: [Transcript show: 'foo'], the '1 halt.' is executed as I mentioned before. However, the debugger does not allow me to access aBlock, there is a subscript out of bound exception. Interestingly, 'block' is accessible without error.
If I now actually use 'block' instead of 'aBlock' in the executed block, then phenomena is reversed. Thus, the variable which is actually referenced in the code is not accessible anymore but gets somehow lost. They also get lost if I use both.
I would still like to understand what is going on here. So any remarks are welcome.
Thanks Stefan
spawn: aBlock "Answer an ErlProcess running the code given in the parameter. The process isscheduled." | proc block | <primitive: 19> "Simulation guard" block := aBlock. proc := Process forContext: [1 halt. aBlock value. Processor terminateActive] asContext priority: Processor activePriority. proc resume. ^ proc
On 29 Sep 2010, at 11:21, Stefan Marr wrote:
On 29 Sep 2010, at 11:01, Igor Stasenko wrote:
On 29 September 2010 11:11, Stéphane Ducasse stephane.ducasse@inria.fr wrote:
no idea but I want to know that too so keep us posted.
Smalltalk specialObjectsArray at: 28. Thats it, Process is a special object, recognized by VM. No other Process (sub)classes can be accepted by it.
Could you elaborate on that? No other process can be accepted for what? Being scheduled, or being executed?
There is also a comment in the comment of Process which suggests that it should be possible: "(If anyone ever makes a subclass of Process, be sure to use allSubInstances in anyProcessesAbove:.)" But even after making the change, that does not seem to be the actual problem.
The process gets execute fine. With a '1 halt.' as the first statement of the aBlock block I even get a debugger. It only fails on accessing variables referenced by the closure with an index out of bound error or something similar.
Erlang>>spawn: aBlock "Answer an ErlProcess running the code given in the parameter. The process is scheduled." | proc | proc := ErlProcess forContext: [1 halt. aBlock value. Processor terminateActive] asContext priority: Processor activePriority. proc resume. ^ proc
Thanks and best regards Stefan
-- Stefan Marr Software Languages Lab Vrije Universiteit Brussel Pleinlaan 2 / B-1050 Brussels / Belgium http://soft.vub.ac.be/~smarr Phone: +32 2 629 2974 Fax: +32 2 629 3525
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
-- Stefan Marr Software Languages Lab Vrije Universiteit Brussel Pleinlaan 2 / B-1050 Brussels / Belgium http://soft.vub.ac.be/~smarr Phone: +32 2 629 2974 Fax: +32 2 629 3525
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
squeak-dev@lists.squeakfoundation.org
-
Eliot Miranda -
Stefan Marr