# HG changeset patch
# User Gregory Szorc <gregory.szorc@gmail.com>
# Date 1453068855 28800
# Node ID e219dbfd0342492eb5695f1a11d1156063aabdb5
# Parent  c183f7b79541560192ab2cc6864308416d137604
localrepo: don't reference transaction from hook closure (issue5043)

Before, the hook() closure (which is called as part of locking hooks)
would maintain a reference to a transaction instance (which should be
finalized by the time lock hooks are called). Because we accumulate
hook() instances when there are multiple transactions per lock, this
would result in holding references to the transaction instances which
would lead to higher memory utilization.

Creating a reference to the hook arguments dict minimizes the number
of objects that are kept alive until the lock release hook runs,
minimizing memory "leaks."

diff -r c183f7b79541 -r e219dbfd0342 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Sun Jan 17 12:10:30 2016 -0800
+++ b/mercurial/localrepo.py	Sun Jan 17 14:14:15 2016 -0800
@@ -1085,9 +1085,15 @@
         def txnclosehook(tr2):
             """To be run if transaction is successful, will schedule a hook run
             """
+            # Don't reference tr2 in hook() so we don't hold a reference.
+            # This reduces memory consumption when there are multiple
+            # transactions per lock. This can likely go away if issue5045
+            # fixes the function accumulation.
+            hookargs = tr2.hookargs
+
             def hook():
                 reporef().hook('txnclose', throw=False, txnname=desc,
-                               **tr2.hookargs)
+                               **hookargs)
             reporef()._afterlock(hook)
         tr.addfinalize('txnclose-hook', txnclosehook)
         def txnaborthook(tr2):