view tests/test-lfs-pointer.py @ 47343:9f798c1b0d89 stable

cext: fix memory leak in phases computation

Without this a buffer whose size in bytes is the number of
changesets in the repository is leaked each time the repository is
opened and changeset phases are computed.

Impact: the current code in hgwebdir creates a new `localrepository`
instance for each HTTP request. Since any pull or push is made of several
requests, a team of 100 people can easily produce thousands of such
requests per day.

Being a low-level malloc, this leak can't be seen with the gc module and
tools relying on that, but was spotted by valgrind immediately.

Reproduction
------------

  for i in range(cl_args.iterations):
      repo = hg.repository(baseui, repo_path)
      rev = repo.revs(rev).first()
      ctx = repo[rev]

  del ctx
  del repo
  # avoid any pollution by other type of leak
  # (that should be fixed in 5.8)
  repoview._filteredrepotypes.clear()

  gc.collect()

Measurements
------------

Resident Set Size (RSS), taken on a clone of
mozilla-central for performance analysis (440 000
changesets).

before:
  5.8+hg19.5ac0f2a8ba72  1000 iterations: 1606MB
  5.8+hg19.5ac0f2a8ba72 10000 iterations: 5723MB
after:
  5.8+hg20.e2084d39e145  1000 iterations:  555MB
  5.8+hg20.e2084d39e145 10000 iterations:  555MB
         (double checked, not a copy/paste error)

(e2084d39e14 is the present changeset, before amendment
of the message to add the measurements)

from __future__ import absolute_import, print_function

# Import something from Mercurial, so the module loader gets initialized.
from mercurial import pycompat

del pycompat  # unused for now

from hgext.lfs import pointer


def tryparse(text):
    r = {}
    try:
        r = pointer.deserialize(text)
        print('ok')
    except Exception as ex:
        print((b'%s' % ex).decode('ascii'))
    if r:
        text2 = r.serialize()
        if text2 != text:
            print('reconstructed text differs')
    return r


t = (
    b'version https://git-lfs.github.com/spec/v1\n'
    b'oid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1'
    b'258daaa5e2ca24d17e2393\n'
    b'size 12345\n'
    b'x-foo extra-information\n'
)

tryparse(b'')
tryparse(t)
tryparse(t.replace(b'git-lfs', b'unknown'))
tryparse(t.replace(b'v1\n', b'v1\n\n'))
tryparse(t.replace(b'sha256', b'ahs256'))
tryparse(t.replace(b'sha256:', b''))
tryparse(t.replace(b'12345', b'0x12345'))
tryparse(t.replace(b'extra-information', b'extra\0information'))
tryparse(t.replace(b'extra-information', b'extra\ninformation'))
tryparse(t.replace(b'x-foo', b'x_foo'))
tryparse(t.replace(b'oid', b'blobid'))
tryparse(t.replace(b'size', b'size-bytes').replace(b'oid', b'object-id'))