do + <DATA> = leak

bsb has asked for the wisdom of the Perl Monks concerning the following question:

After considerable effort I discovered what seems like a leak caused by repeatedly "do"ing n file that reads from it's DATA handle. Closing it stops the leak.

Is this a known problem?

$ perl -nwe 'BEGIN {print "$$\n"} do "file_with_DATA.pl"'
$ head -n 10 file_with_DATA.pl 
() = <DATA>;
#close(DATA);
1;
__DATA__
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
[... Many more lines of "AAAA"s ...]
[download]

Update:
p5pmsg Potential to leak DATA filehandles
man perldata:
The filehandle is left open pointing to the contents after __DATA__. It is the program's responsibility to "close DATA" when it is done reading from it.

Comment on do + <DATA> = leak Download Code

Replies are listed 'Best First'.
Re: do + <DATA> = leak by simonm (Vicar) on Dec 03, 2003 at 03:46 UTC
Yup, I get a similar effect in Perl v5.6.0 built for darwin -- it leaks unless there's an explicit close(). In fact, if you let the test script run long enough, it eventually runs into some other kind of problem on repetition number 252; perhaps it's running out of file handles? perl -w -l -e 'BEGIN {print "$$\n"} while ( 1 ) { do "file_with_DATA.pl"; print( ( ++ $i ) . ": " . `date`, ` ps -o rssize $$` ) }'	[reply] [d/l]
Re: do + <DATA> = leak by Roger (Parson) on Dec 03, 2003 at 02:20 UTC
Don't know what sort of leak you are talking about. When I tried to run it, it just waits for me to hit the return key. `perl -h` explains that the -n switch assume `while (<>) { ... }` loop around program, so it is waiting for input from STDIN. So I kept hitting <ENTER>, and watched the memory usage of perl on another terminal. The memory usage seemed quite stable at 4224k. Note that I did not have the `close(DATA)` line in my test script.	[reply] [d/l] [select]
Re: Re: do + <DATA> = leak by bsb (Priest) on Dec 03, 2003 at 03:18 UTC
My real file has a lot more lines of "AAAAA"s. It does seem to leak for me: $ yes\|perl -nwe 'BEGIN {print "$$\n"} do "file_with_DATA.pl"; print `p +s -o rssize $$`' 26279 RSS 1120 RSS 1128 RSS 1132 [..etc..] RSS 5564 RSS 5572 RSS 5576 [download] This is perl, v5.6.1 built for i386-linux	[reply] [d/l]
Re: Re: Re: do + <DATA> = leak by Roger (Parson) on Dec 03, 2003 at 03:32 UTC
Ah... I see it. I am using perl 5.6.1 for sun-solaris. The memory leak remains even after I add the `close(DATA);`	[reply] [d/l]