From 32d94d4e85f14670b72beb2ded96b518d78e2dbb Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Fri, 30 Jul 2021 10:53:22 +0300
Subject: [PATCH] reset walked set as epoch boundaries are crossed

the walk is BFS, so we can do this!
---
 blockstore/splitstore/splitstore_compact.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/blockstore/splitstore/splitstore_compact.go b/blockstore/splitstore/splitstore_compact.go
index 7628e2bde..2ae5c9e68 100644
--- a/blockstore/splitstore/splitstore_compact.go
+++ b/blockstore/splitstore/splitstore_compact.go
@@ -616,7 +616,7 @@ func (s *SplitStore) endTxnProtect() {
 
 func (s *SplitStore) walkChain(ts *types.TipSet, inclState, inclMsgs abi.ChainEpoch,
 	visitor ObjectVisitor, f func(cid.Cid) error) error {
-	walked := cid.NewSet()
+	var walked *cid.Set
 	toWalk := ts.Cids()
 	walkCnt := 0
 	scanCnt := 0
@@ -687,6 +687,10 @@ func (s *SplitStore) walkChain(ts *types.TipSet, inclState, inclMsgs abi.ChainEp
 			return err
 		}
 
+		// the walk is BFS, so we can reset the walked set in every iteration and avoid building up
+		// a set that contains all blocks (1M epochs -> 5M blocks -> 200MB worth of memory and growing
+		// over time)
+		walked = cid.NewSet()
 		walking := toWalk
 		toWalk = nil
 		for _, c := range walking {