view tests/test-diff-antipatience.t @ 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)

#testcases bdiff xdiff

#if xdiff
#require xdiff
  $ cat >> $HGRCPATH <<EOF
  > [experimental]
  > xdiff = true
  > EOF
#endif

Test case that makes use of the weakness of patience diff algorithm

  $ hg init
  >>> open('a', 'wb').write(('\n'.join(list('a' + 'x' * 10 + 'u' + 'x' * 30 + 'a\n'))).encode('ascii')) and None
  $ hg commit -m 1 -A a
  >>> open('a', 'wb').write(('\n'.join(list('b' + 'x' * 30 + 'u' + 'x' * 10 + 'b\n'))).encode('ascii')) and None
#if xdiff
  $ hg diff
  diff -r f0aeecb49805 a
  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,4 +1,4 @@
  -a
  +b
   x
   x
   x
  @@ -9,7 +9,6 @@
   x
   x
   x
  -u
   x
   x
   x
  @@ -30,6 +29,7 @@
   x
   x
   x
  +u
   x
   x
   x
  @@ -40,5 +40,5 @@
   x
   x
   x
  -a
  +b
   
#else
  $ hg diff
  diff -r f0aeecb49805 a
  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,15 +1,4 @@
  -a
  -x
  -x
  -x
  -x
  -x
  -x
  -x
  -x
  -x
  -x
  -u
  +b
   x
   x
   x
  @@ -40,5 +29,16 @@
   x
   x
   x
  -a
  +u
  +x
  +x
  +x
  +x
  +x
  +x
  +x
  +x
  +x
  +x
  +b
   
#endif