stack overflow with moderately complex data structures [rt.cpan.org #97525]

[atoomic]

Migrated from rt.cpan.org#97525 (status was 'open')

Requestors:

• [email protected]

From [email protected] on 2014-07-26 13:33:50:

This comes from the discussion of [rt.cpan.org #97508]:

$ ulimit -s
8192
$ perl -e 'use Clone qw(clone); $t = [$t] for 1..30000; clone $t'
$ perl -e 'use Clone qw(clone); $t = [$t] for 1..40000; clone $t'
Segmentation fault (core dumped)
$ ulimit -s 16348
$ perl -e 'use Clone qw(clone); $t = [$t] for 1..40000; clone $t'
$ perl -e 'use Clone qw(clone); $t = [$t] for 1..60000; clone $t'
$ perl -e 'use Clone qw(clone); $t = [$t] for 1..70000; clone $t'
Segmentation fault (core dumped)
$ dpkg -l perl libclone-perl | grep ii
ii  libclone-perl  0.36-1           amd64  module for recursively copying Perl datatypes
ii  perl           5.18.2-2ubuntu1  amd64  Larry Wall's Practical Extraction and Report Language

The same happens with:
$ perl -e 'use threads; $t = [$t] for 1..30000; (async {})->join'
Segmentation fault (core dumped)
$ perl -e 'use Storable qw(dclone); $t = [$t] for 1..30000; dclone $t'
Segmentation fault (core dumped)

From [email protected] on 2015-11-06 14:42:26:

According to this stack trace (generated by stsc) this is a recursion only involving av_clone() and sv_clone() from auto/Clone/Clone.so , which is completely internal to the Clone distribution:

http://perlpunks.de/paste/show/563ba05b.425c.da?plain=1

I would humbly suggest switching from recursion to some explicitly coded iterative traversal (e.g. maintaining an explicit recursion stack in the heap).

Ralf

[atoomic]

with perl 5.28.0

> perl -e 'use Storable qw(dclone); $t = [$t] for 1..30000; dclone $t'
Max. recursion depth with nested structures exceeded at -e line 1.