Re: [PATCH] commit-graph: avoid leaking topo_levels slab in write_commit_graph()

On 2/19/2021 10:36 PM, Junio C Hamano wrote:

"Andrzej Hunt via GitGitGadget" [off-list ref] writes:

quoted

From: Andrzej Hunt <redacted>

write_commit_graph initialises topo_levels using init_topo_level_slab(),
next it calls compute_topological_levels() which can cause the slab to
grow, we therefore need to clear the slab again using
clear_topo_level_slab() when we're done.

First introduced in 72a2bfcaf01860ce8dd6921490d903dc0ad59c89 - which
is currently only in master and not on maint.

Thanks.  

Forwarding to those who were involved in the said commit for
insights.

quoted

index ed31843fa522..9529ec552139 100644

--- a/commit-graph.c
+++ b/commit-graph.c

@@ -2471,6 +2471,7 @@ int write_commit_graph(struct object_directory *odb,
 	free(ctx->graph_name);
 	free(ctx->commits.list);
 	oid_array_clear(&ctx->oids);
+	clear_topo_level_slab(&topo_levels);

This change looks like a sane change to me. It definitely fixes a leak.
The leak "wasn't hurting anybody" because write_commit_graph() is only
called at most once per process, and the process closes itself out
shortly after. Still, it's good to have good memory hygiene here.

Thanks,
-Stolee