[PATCH v2 3/3] commit-graph: reduce initial oid allocation

From: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date: Oct 3, 2018, 17:12 UTC
Message-ID: <1002fd34fc57e929265d07ad6e6010116b27b7a9.1538586732.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.42.v2.git.gitgitgadget@gmail.com>

From: Derrick Stolee <dstolee@microsoft.com>

While writing a commit-graph file, we store the full list of commits in a flat list. We use this list for sorting and ensuring we are closed under reachability.

The initial allocation assumed that (at most) one in four objects is a commit. This is a dramatic over-count for many repos, especially large ones. Since we grow the repo dynamically, reduce this count by a factor of eight. We still set it to a minimum of 1024 before allocating.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 commit-graph.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/commit-graph.c b/commit-graph.c
index ceca6026b0..e773703e1d 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -720,7 +720,7 @@ void write_commit_graph(const char *obj_dir,
 	struct progress *progress = NULL;
 
 	oids.nr = 0;
-	oids.alloc = approximate_object_count() / 4;
+	oids.alloc = approximate_object_count() / 32;
 	oids.progress = NULL;
 	oids.progress_done = 0;

-- 
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