From 5473aca3767b00eab502b34a37b595de099980ae Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Wed, 3 Jan 2024 07:22:39 +0100 Subject: reftable/merged: really reuse buffers to compute record keys In 829231dc20 (reftable/merged: reuse buffer to compute record keys, 2023-12-11), we have refactored the merged iterator to reuse a pair of long-living strbufs by relying on the fact that `reftable_record_key()` tries to reuse already allocated strbufs by calling `strbuf_reset()`, which should give us significantly fewer reallocations compared to the old code that used on-stack strbufs that are allocated for each and every iteration. Unfortunately, we called `strbuf_release()` on these long-living strbufs that we meant to reuse on each iteration, defeating the optimization. Fix this performance issue by not releasing those buffers on iteration anymore, where we instead rely on `merged_iter_close()` to release the buffers for us. Using `git show-ref --quiet` in a repository with ~350k refs this leads to a significant drop in allocations. Before: HEAP SUMMARY: in use at exit: 21,163 bytes in 193 blocks total heap usage: 1,410,148 allocs, 1,409,955 frees, 61,976,068 bytes allocated After: HEAP SUMMARY: in use at exit: 21,163 bytes in 193 blocks total heap usage: 708,058 allocs, 707,865 frees, 36,783,255 bytes allocated Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- reftable/merged.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/reftable/merged.c b/reftable/merged.c index 556bb5c556..a28bb99aaf 100644 --- a/reftable/merged.c +++ b/reftable/merged.c @@ -128,8 +128,6 @@ static int merged_iter_next_entry(struct merged_iter *mi, done: reftable_record_release(&entry.rec); - strbuf_release(&mi->entry_key); - strbuf_release(&mi->key); return err; } -- cgit v1.2.3