[antlr-interest] Re: Intermitent bug with ANTLR.

[Oliver Zeigermann]

Hi guys,

I really can't believe this is a VM bug (although I just found an 
obvious one the other day, so, hmmmm, maybe). What I rather suspect is 
there is some sort of race. At least this is indicated by this 
undeterministic behavior. To have a race you need at least two threads 
running. As far as I know ANTLR is strictly single-threaded, right? But, 
trara, XPA is *not*. It uses a producer/consumer thing to give both SAX 
parser an ANTLR the impression they are the master of it all. Although 
this code is very simple, there might still be a bug in it. If you can 
give me any hint upon which conditions this error occurs, I would highly 
appreciate this.

Cheers,
Oliver


lachinois2002 wrote:
> Hi Monty,
> 
> Well... I'm outa luck, after adding 2 or 3 rules to my grammar it 
> seems like the bug doesnt show up anymore. This really looks like a 
> java VM bug. In anycase, if this happens again I'll trace it and 
> hope it behaves the same with the trace activated.
> 
> Daniel Shane
> 
> --- In antlr-interest at yahoogroups.com, mzukowski at y... wrote:
> 
>>To continue on the theme of the week, try building with -trace and 
> 
> then
> 
>>running.  I'd be curious to see the difference between success & 
> 
> failure.
> 
>>Monty
>>
>>-----Original Message-----
>>From: Daniel Shane [mailto:lachinois at h...] 
>>Sent: Wednesday, January 28, 2004 11:49 AM
>>To: antlr-interest at yahoogroups.com
>>Subject: [antlr-interest] Intermitent bug with ANTLR.
>>
>>Hi everyone, mostly Terence.
>>
>>I will greatly need your help on this one. I have a grammar (that 
> 
> uses XPA) 
> 
>>and, listen to this, I sometimes get a grammar error, and 
> 
> sometimes not by 
> 
>>executing the same command line with the same input.
>>
>>Here is what happens:
>>
>>$ java -cp 
>>"/usr/local/soft/antlr-2.7.2/lib/antlr.jar:/usr/local/soft/xpa-
> 
> 1.0.1/lib/xpa
> 
>>1_0_1-full.jar:.:Code" 
>>MainRegulationParser tmp/Fr/C.R.C.,_c._100.06-MTE.html > /tmp/g
>>
>>$ java -cp 
>>"/usr/local/soft/antlr-2.7.2/lib/antlr.jar:/usr/local/soft/xpa-
> 
> 1.0.1/lib/xpa
> 
>>1_0_1-full.jar:.:Code" 
>>MainRegulationParser tmp/Fr/C.R.C.,_c._100.06-MTE.html > /tmp/g
>>
>>$ java -cp 
>>"/usr/local/soft/antlr-2.7.2/lib/antlr.jar:/usr/local/soft/xpa-
> 
> 1.0.1/lib/xpa
> 
>>1_0_1-full.jar:.:Code" 
>>MainRegulationParser tmp/Fr/C.R.C.,_c._100.06-MTE.html > /tmp/g
>>
>>$ java -cp 
>>"/usr/local/soft/antlr-2.7.2/lib/antlr.jar:/usr/local/soft/xpa-
> 
> 1.0.1/lib/xpa
> 
>>1_0_1-full.jar:.:Code" 
>>MainRegulationParser tmp/Fr/C.R.C.,_c._100.06-MTE.html > /tmp/g
>>line 3: expecting "<IdOfRegulation>", found 'TitleOfAct'
>>
>>$ java -cp 
>>"/usr/local/soft/antlr-2.7.2/lib/antlr.jar:/usr/local/soft/xpa-
> 
> 1.0.1/lib/xpa
> 
>>1_0_1-full.jar:.:Code" 
>>MainRegulationParser tmp/Fr/C.R.C.,_c._100.06-MTE.html > /tmp/g
>>
>>$
>>
>>These invocation were done in sequence and the input file has not 
> 
> changed 
> 
>>between invocations. I printed some debug out of ANTLR to show the 
> 
> sequence 
> 
>>of tokens that have been read and in both cases the token sequence 
> 
> is the 
> 
>>same.
>>
>>Something is happening in ANTLR that is causing it to take a 
> 
> different path 
> 
>>for what seems like a random reason.
>>
>>This is really causing me a headache, and I can trace the problem 
> 
> to one 
> 
>>rule I added in the grammar. If I remove this rule, then I do not 
> 
> get this 
> 
>>strange behavior (BTW, the rule is simple, so I'm not doing 
> 
> anything tricky 
> 
>>here). I really cannot see why this additionnal rule would break 
> 
> anything 
> 
>>and specially not like this.
>>
>>I really out of clues here, what would you like me to do to give 
> 
> you some 
> 
>>additionnal information? Do you want the java files/grammar so 
> 
> that you can 
> 
>>run it on your setup see if it does the same? Would you like an 
> 
> ssh access 
> 
>>to this linux machine to see for yourself? Do you think the bug 
> 
> arrises from
> 
>>XPA?
>>
>>I'm running on Linux, RedHat 9 with the SUN JDK 1.4.2 for linux.
>>
>>Daniel Shane
>>
>>_________________________________________________________________
>>MSN Search, le moteur de recherche qui pense comme vous !  
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>>
>>
>> 
>>
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