# HG changeset patch
# User Joerg Sonnenberger <joerg@bec.de>
# Date 1603237689 -7200
# Node ID 8719a5b684199bcdfb8e5137573e91c9f5a8a62b
# Parent  6620caf427ecf0b8b1dbc77aff9b498c15857a08
revlog: use LRU for the chain cache

For a large repository, this reduces the number of filelog instances and
associated data a lot. For a 1% speed penalty, it reduces peak RSS by
20% for the full NetBSD test repository.

Differential Revision: https://phab.mercurial-scm.org/D9235

diff -r 6620caf427ec -r 8719a5b68419 mercurial/revlog.py
--- a/mercurial/revlog.py	Wed Oct 14 08:38:58 2020 -0700
+++ b/mercurial/revlog.py	Wed Oct 21 01:48:09 2020 +0200
@@ -668,7 +668,7 @@
         if not self._chunkcache:
             self._chunkclear()
         # revnum -> (chain-length, sum-delta-length)
-        self._chaininfocache = {}
+        self._chaininfocache = util.lrucachedict(500)
         # revlog header -> revlog compressor
         self._decompressors = {}
 
@@ -2550,7 +2550,7 @@
 
         # then reset internal state in memory to forget those revisions
         self._revisioncache = None
-        self._chaininfocache = {}
+        self._chaininfocache = util.lrucachedict(500)
         self._chunkclear()
 
         del self.index[rev:-1]