Dpkg::Control: Fix memory leak due to objects not being garbage-collected

When runnung a Perl script that repeatedly creates unreferenced
Dpkg::Control objects, the perl process consumes memory without limit.

A one-line sample:

  perl -MDpkg::Control -e 'Dpkg::Control->new while 1'

It would be expected from a script like this to have a constant memory
usage, as the Dpkg::Control objects are garbage-collected soon after
being created. What happens instead, is that after running for thirty
seconds, perl has consumed over 100 MiB of memory.

By contrast, the same test using Dpkg::Index consumes a constant 6 MiB.

This problem effectively means that a process can't operate on a large
number of Dpkg::Control objects sequentially.

The cause of the problem appears to be a circular reference between a
Dpkg::Control::Hash and its contained tied hash. This patch explicitly
breaks this loop when a Dpkg::Control::Hash is destroyed, following
the advice in perlobj(1).

Closes: #669012

Signed-off-by: Guillem Jover <guillem@debian.org>

0 files changed, 0 insertions, 0 deletions