Re: [Flex-help] Generated scanner consumes too much time - help request

[Simon S. <sim...@gn...>]

Thank you for answering and about the notes about the progress.

I'll try 2.6.5 dev on Monday or Tuesday (or whenever the pull you
refered to was done) - Can you please leave a link to the PR allowing me
to subscribe to it?
I'll report back next week when I have access to the test environment.

If someone stumbles over bad practice in the referred scanner.l I'd
still like to know about it ;-)

Thank you for the analyzer,
Simon

Am 16.03.2018 um 21:32 schrieb Will Estes:
> There have been some performance changes since that version, yes, so first I would see how things stand with 2.6.4. There will be a 2.6.5 soonish -- one more pull request remains and then I'll be putting in tooling in to make releasing flex easier -- just to give you a sense of the timeline for 2.6.5 which also contains a fair number of changes since 2.6.4.
> 
> On Friday, 16 March 2018,  9:05 pm +0100, Simon Sobisch <sim...@gn...> wrote:
> 
>>
>> Hi flex-users and developers,
>>  
>> I've just did a profiling (using callgrind) on the GnuCOBOL compiler
>> (parsing only) with 2,500,000 LOC and found out that the recent
>> scanner[1] consumes most of the time:
>>
>> * 44% spent in yylex (16% of these are spent in GnuCOBOL internal
>> functions leaving 28% of the complete parser process in this single flex
>> generated file)
>>
>> * 13% in yy_get_previous_state
>>
>> * 5.6% spent in yy_get_next_buffer with 1.3% in fgets
>>  
>> Removing all the "noise" there is still over 25% spent in the scanner
>> and "get_previous_state" doesn't sound like it should be called that often.
>>  
>> I guess there are some bad practices used in scanner.l, but I don't know
>> what to look out for.
>> Can you please have a look at this and post suggestions or point to bad
>> practice found in there?
>>  
>> Is the amount of calls to get_previous_state normal?
>>  
>> scanner.c was generated with flex 2.5.37 - Do you expect a speedup with
>> a more recent release?
>>  
>> Thank you for taking the time to answer and maybe even for checking the
>> source,
>> Simon
>>
>> [1] https://sourceforge.net/p/open-cobol/code/HEAD/tree/trunk/cobc/scanner.l
>>
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>