Hi,
I was wondering if anyone can help me figure out a problem having to
do with accessing a scalar variable with vec().. it's illustrated by
this little test program:
#!/usr/bin/perl
my $foo = '';
vec($foo, (1<<$ARGV[0])-1, 8)=1;
I can run this with the argument 27, and it works just fine. Perl
uses a bit more than 128 MB virtual memory before exiting, just as one
would expect. When I run the program with n=28 (perl 5.8.8, linux), I
get:
Out of memory!
I have plenty of virtual memory, so there's no reason a malloc would
fail that I can think of. From looking at perldebguts and malloc.c in
the source, it looks like sbrk is also used (is this just for package
globals?), so I tried using a lexical variable and I tried getting a
reference to an anonymous scalar with $vec = *foo{SCALAR} then
extending $$vec, but the same thing happened.
I can create a string of the same size using something like 'chr(0) x
(1<<$ARGV[0])', and perl will happily create a character array of
length 2^28 (and use half a gig to do so of course ;). But even if I
extend the scalar to the correct length in this fashion, I still get
fatal errors when trying to write into it with vec().
Then I thought maybe there's something like a maximum bucket size in
the perl allocator, which vec() lvalues don't handle properly, so I
tried compiling perl with -DNO_FANCY_MALLOC and -DPLAIN_MALLOC. I
still get the same error. I don't understand why a 128 MB scalar
string is no problem but 256 MB causes this?
I've noticed that with perl 5.8.6 I get the error "panic: realloc at
...". Perhaps it's the same error condition described more
accurately? But according to perldiag, this is an internal error that
indicates something tried to allocate a negative number of bytes!
Should I submit this with perlbug?
Thanks,
Kyle Cronan
<[EMAIL PROTECTED]>
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
<http://learn.perl.org/> <http://learn.perl.org/first-response>
