Sorry for the top post... However, if the issue with ctest being slow
can be fixed by using PCRE in CMake, that is good news. We can just
link in the library, and replace that small part of CMake internal code
that has the performance problem. This should not break backwards
compatibility. It also gives us a way to slowly bring in PCRE into CMake.
Alex, is there a way you can try PCRE in CMake to see if it fixes the
problem?
-Bill
On 11/14/2011 1:13 PM, Pau Garcia i Quiles wrote:
Hi,
Check this:
A wish a day 11: Perl Compatible Regular Expressions in CMake
http://www.elpauer.org/?p=684
Unfortunately the student turned out to be a total fraud: he knew
nothing about CMake, regular expressions (much less PCRE!), git, and
could barely manage with C/C++. After months of explaining *really*
basic stuff (such as the difference between a static and a shared
library), he silently gave up.
I do have an initial implementation and extensive information on how to
implement PCRE in CMake. It's just I don't have enough spare time to do
that, and at work I cannot justify investing so many time in CMake for
free (for now, we don't need advanced regular expressions)
On Mon, Nov 14, 2011 at 6:57 PM, Alexandru Ciobanu
<a...@rogue-research.com <mailto:a...@rogue-research.com>> wrote:
Hi,
Our team is affected by issue 0012381, that causes extremely poor
performance by CTest. Details here:
http://public.kitware.com/Bug/view.php?id=12381
I've created a small test case that demonstrates the problem. Please
find the .cpp file attached.
>From what I see, the RegularExpression class uses Henry Spencer
regex implementation, which is known to be slow for some cases.
On my machine, the attached example runs in 0.8 sec. Just to process
one string!
$ time ./repr
real 0m0.865s
user 0m0.862s
sys 0m0.002s
Grep can process 100k such strings in 0.5 sec (which includes
reading a 570MB file from disk):
$ wc -l big.str.txt
100000 big.str.txt
$ ls -lh big.str.txt
-rw-r--r-- 1 alex staff 572M 14 Nov 12:30 big.str.txt
$ time grep "([^:]+): warning[ \t]*[0-9]+[ \t]*:" big.str.txt
real 0m0.525s
user 0m0.255s
sys 0m0.269s
I see three ways to fix this problem:
A) use a trusted 3rd party regex library, like re2 or pcre
B) find another self-contained regex implementation
C) try to use the standard POSIX regex available in regex.h on
most systems
I tried to find another self-contained regex implementation, that we
could use. I found Tiny REX, but it is as slow, in this case, as
Henry Spencer's implementation.
So what do you think is the best way to proceed about this problem?
sincerely,
Alex Ciobanu
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(Due to my workload, I may need 10 days to answer)
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