Random exceptions terminating root process

Hi,

Here's the test case code I mentioned earlier. It's probably
my code
that's at fault, rather than the VM, but it's still very
strange behaviour.

When you run TerminationExperiment's #run, it can sometimes
reach
several tens of thousands of iterations of busyLoop before
faulting, but
will often fault before 20,000 iterations have completed on
my machine.

When you run #run2, things behave as I would have expected
them to
behave. No faulting occurs, and the process is sensibly
terminated.

Here's a selection of some of the faults I see from #run
after several
seconds. Each comes at the end of a single run of the
script, as attached.

Object: '' error: Invalid argument : must be a SmallInteger
SystemExceptions.WrongClass(Exception)>>signal
SystemExceptions.WrongClass class>>signalOn:mustBe:
SystemExceptions.WrongClass class>>signalOn:mustBe:
String(Object)>>checkIndexableBounds:put:
String>>at:put:
String class(ArrayedCollection class)>>with:
Character>>asString
[] in TextCollector>>showCr:
[] in Semaphore>>critical:
BlockClosure>>ensure:
Semaphore>>critical:
TextCollector>>showCr:
String(Object)>>printNl
TerminationExperiment>>busyLoop
TerminationExperiment>>run
UndefinedObject>>executeStatements

Object: nil error: did not understand #generality
MessageNotUnderstood(Exception)>>signal
UndefinedObject(Object)>>doesNotUnderstand:
#generality
SmallInteger>>+
FileStream(FileDescriptor)>>write:from:to:
FileStream>>flush
FileStream(Stream)>>nextPutAllFlush:
TextCollector>>primNextPutAll:
[] in TextCollector>>showCr:
[] in Semaphore>>critical:
BlockClosure>>ensure:
Semaphore>>critical:
TextCollector>>showCr:
String(Object)>>printNl
TerminationExperiment>>busyLoop
TerminationExperiment>>run
UndefinedObject>>executeStatements

Object: String error: Invalid argument 'b': must be a
SmallInteger
SystemExceptions.WrongClass(Exception)>>signal
SystemExceptions.WrongClass class>>signalOn:mustBe:
SystemExceptions.WrongClass class>>signalOn:mustBe:
String class(Behavior)>>new:
String(Collection)>>copyEmpty:
String(ArrayedCollection)>>copyFrom:to:
WriteStream>>contents
String(Object)>>printString
String(Object)>>printNl
TerminationExperiment>>busyLoop
TerminationExperiment>>run
UndefinedObject>>executeStatements

Object: 3 error: did not understand
#replaceFrom:to:with:startingAt:
MessageNotUnderstood(Exception)>>signal
SmallInteger(Object)>>doesNotUnderstand:
#replaceFrom:to:with:startingAt:
String(ArrayedCollection)>>copyFrom:to:
WriteStream>>contents
String(Object)>>printString
String(Object)>>printNl
TerminationExperiment>>busyLoop
TerminationExperiment>>run
UndefinedObject>>executeStatements


This one includes the end of the stdout, to illustrate an
odd doubling
of 'c':

'a'
'b'
'c''c'Object: nil error: did not understand #generality
MessageNotUnderstood(Exception)>>signal
UndefinedObject(Object)>>doesNotUnderstand:
#generality
SmallInteger>>+
FileStream(FileDescriptor)>>write:from:to:
FileStream>>flush
FileStream(Stream)>>nextPutAllFlush:
TextCollector>>primNextPutAll:
[] in TextCollector>>showCr:
[] in Semaphore>>critical:
BlockClosure>>ensure:
Semaphore>>critical:
TextCollector>>showCr:
String(Object)>>printNl
TerminationExperiment>>busyLoop
TerminationExperiment>>run
UndefinedObject>>executeStatements

Object: String error: did not understand #copyEmpty:
MessageNotUnderstood(Exception)>>signal
String class(Object)>>doesNotUnderstand: #copyEmpty:
WriteStream>>growCollection
WriteStream>>nextPut:
String>>printOn:
String(Object)>>printString
String(Object)>>printNl
TerminationExperiment>>busyLoop
TerminationExperiment>>run
UndefinedObject>>executeStatements

etc. etc.

Tony
-- 
 [][][] Tony Garnock-Jones     | Mob: +44 (0)7905 974 211
   [][] LShift Ltd             | Tel: +44 (0)20 7729 7060
 []  [] http://www.lshift.net/ |
Email: tonyglshift.net

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Tony Garnock-Jones wrote:
> Hi,
> 
> Here's the test case code I mentioned earlier. It's
probably my code
> that's at fault, rather than the VM, but it's still
very strange behaviour.

No, it's the VM.  You're right -- it's a bad idea to
terminate a 
CallinProcess and I knew that but forgot today; it wouldn't
terminate at 
all if it was not for those random exceptions (which are a
different 
bug).  Please file the bug report and attach the code there
too.

Paolo


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