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

[Oliver Zeigermann]

I just checked this and I guess it actually does not apply. As far as I 
know Daniel uses the XPA XML parser, not a SAX one to drive ANTLR, but 
this one is single-threaded. Thus it can't be a race and I am clueless 
as well...

Oliver

Oliver Zeigermann wrote:
> 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 !  
>>>http://fr.ca.search.msn.com/
>>>
>>>
>>>
>>>
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>>
>>
>>
>> 
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