view tests/test-merge2.t @ 23226:5dcaed20b27c stable

changegroup: sparsely populate fnodes

Previously, fnodes had a key and empty dict value for every element in
changedfiles. This is somewhat wasteful. Empty dicts in CPython consume
a lot more memory than you would expect - 280 bytes.

On mozilla-central, which has ~190,000 files/fnodes keys, the previous
loop populating fnodes allocated 91,924 KB of memory, most of that for
the empty dicts.

With this patch in place, our peak RSS during mozilla-central clone
drops:

before:  364,356 KB
after:   326,008 KB
delta:   -38,348 KB

When combined with the previous patch, total peak RSS decrease is now
190,116 KB.

  $ hg init t
  $ cd t
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ rm b
  $ hg update 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo This is file b2 > b
  $ hg add b
  $ hg commit -m "commit #2"
  created new head
  $ cd ..; rm -r t

  $ mkdir t
  $ cd t
  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ rm b
  $ hg update 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo This is file b2 > b
  $ hg commit -A -m "commit #2"
  adding b
  created new head
  $ cd ..; rm -r t

  $ hg init t
  $ cd t
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ rm b
  $ hg remove b
  $ hg update 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo This is file b2 > b
  $ hg commit -A -m "commit #2"
  adding b
  created new head

  $ cd ..