[R] Memory management in R

[Lorenzo Isella]

Dear All,
I am experiencing some problems with a script of mine.
It crashes with this message

Error in grepl(fut_string, past_string) :
   invalid regular expression 
'12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12653a6#12
Calls: entropy_estimate_hash -> total_entropy_lz -> entropy_lz -> grepl
In addition: Warning message:
In grepl(fut_string, past_string) : regcomp error:  'Out of memory'
Execution halted

To make a long story short, I use some functions which eventually call 
grepl on very long strings to check whether a certain substring is part 
of a longer string.
Now, the script technically works (it never crashes when I run it on a 
smaller dataset) and the problem does not seem to be RAM memory (I have 
several GB of RAM on my machine and its consumption never shoots up so 
my machine never resorts to swap memory).
So (though I am not an expert) it looks like the problem is some 
limitation of grepl or R memory management.
Any idea about how I could tackle this problem or how I can profile my 
code to fix it (though it really seems to me that I have to find a way 
to allow R to process longer strings).
Any suggestion is appreciated.
Cheers

Lorenzo