[antlr-interest] Re: Local lookahead depth

Tom Zagotta tzagotta1 at sienasystems.com
Mon Nov 10 14:16:29 PST 2003


> Do the math.  A modern disk drive will sustain a bandwidth of 
> 10-15 MB/s.  You have described a problem in which disk usage 
> would be predominantly sequential (one read and one write per 
> pass), and a large fraction of the disk I/O can be overlapped 
> with computation.  It is decidedly not a "one hour or ten" 
> issue--the performance differential is unlikely to be more 
> than a few percent, provided that you treat the disk as a 
> block-access device.  Besides, between stuff discarded during 
> lexing and stuff discarded during parsing, that 100 MB is 
> likely to shrink into 1-2 MB of tokens and 10-20 MB of syntax tree.

Sorry to interject here -- in my view, performance is always important.  If
I build a parser with ANTLR that takes 10 seconds to parse a file, but my
competitor's parser takes 3 seconds, then I am in trouble.

ANTLR should have best-in-class runtime performance, in my opinion.  We
shouldn't settle for less, especially for academic reasons.

Best regards,

- Tom


 

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