From ce1f213cc91cf545736048f28117fe1de89b8134 Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Mon, 8 Apr 2024 14:17:04 +0200 Subject: reftable/block: reuse `zstream` state on inflation When calling `inflateInit()` and `inflate()`, the zlib library will allocate several data structures for the underlying `zstream` to keep track of various information. Thus, when inflating repeatedly, it is possible to optimize memory allocation patterns by reusing the `zstream` and then calling `inflateReset()` on it to prepare it for the next chunk of data to inflate. This is exactly what the reftable code is doing: when iterating through reflogs we need to potentially inflate many log blocks, but we discard the `zstream` every single time. Instead, as we reuse the `block_reader` for each of the blocks anyway, we can initialize the `zstream` once and then reuse it for subsequent inflations. Refactor the code to do so, which leads to a significant reduction in the number of allocations. The following measurements were done when iterating through 1 million reflog entries. Before: HEAP SUMMARY: in use at exit: 13,473 bytes in 122 blocks total heap usage: 23,028 allocs, 22,906 frees, 162,813,552 bytes allocated After: HEAP SUMMARY: in use at exit: 13,473 bytes in 122 blocks total heap usage: 302 allocs, 180 frees, 88,352 bytes allocated Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- reftable/reader.c | 1 + 1 file changed, 1 insertion(+) (limited to 'reftable/reader.c') diff --git a/reftable/reader.c b/reftable/reader.c index aacd5f1337..481dff10d4 100644 --- a/reftable/reader.c +++ b/reftable/reader.c @@ -459,6 +459,7 @@ static int reader_seek_linear(struct table_iter *ti, * we would not do a linear search there anymore. */ memset(&next.br.block, 0, sizeof(next.br.block)); + next.br.zstream = NULL; next.br.uncompressed_data = NULL; next.br.uncompressed_cap = 0; -- cgit v1.3