From 1f3e0606ee42f5cec594b2c34b17d2aafcb47faf Mon Sep 17 00:00:00 2001
From: fudongbai <296179868@qq.com>
Date: Mon, 17 May 2021 19:32:39 +0800
Subject: [PATCH 1/2] use more aggressive write cache policy

---
 consensus/parlia/parlia.go   |  2 +-
 consensus/parlia/snapshot.go | 12 +++++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/consensus/parlia/parlia.go b/consensus/parlia/parlia.go
index 438042aff2..a8976fd4ad 100644
--- a/consensus/parlia/parlia.go
+++ b/consensus/parlia/parlia.go
@@ -868,7 +868,7 @@ func (p *Parlia) EnoughDistance(chain consensus.ChainReader, header *types.Heade
 	if err != nil {
 		return true
 	}
-	return snap.enoughDistance(p.val)
+	return snap.enoughDistance(p.val, header)
 }
 
 // CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
diff --git a/consensus/parlia/snapshot.go b/consensus/parlia/snapshot.go
index 05aa8de64f..dc83d92c8d 100644
--- a/consensus/parlia/snapshot.go
+++ b/consensus/parlia/snapshot.go
@@ -244,17 +244,23 @@ func (s *Snapshot) inturn(validator common.Address) bool {
 	return validators[offset] == validator
 }
 
-func (s *Snapshot) enoughDistance(validator common.Address) bool {
+func (s *Snapshot) enoughDistance(validator common.Address, header *types.Header) bool {
 	idx := s.indexOfVal(validator)
 	if idx < 0 {
 		return true
 	}
 	validatorNum := int64(len(s.validators()))
+	if validatorNum == 1 {
+		return true
+	}
+	if validator == header.Coinbase {
+		return false
+	}
 	offset := (int64(s.Number) + 1) % int64(validatorNum)
 	if int64(idx) >= offset {
-		return int64(idx)-offset >= validatorNum/2
+		return int64(idx)-offset >= validatorNum-2
 	} else {
-		return validatorNum+int64(idx)-offset >= validatorNum/2
+		return validatorNum+int64(idx)-offset >= validatorNum-2
 	}
 }
 

From 571a3170923bccf899d3ac9fb9f74d3605b5b8b8 Mon Sep 17 00:00:00 2001
From: fudongbai <296179868@qq.com>
Date: Wed, 19 May 2021 11:46:46 +0800
Subject: [PATCH 2/2] fix ungraceful shutdown issue

---
 eth/backend.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/eth/backend.go b/eth/backend.go
index 224253d4e1..2247b94b5d 100644
--- a/eth/backend.go
+++ b/eth/backend.go
@@ -574,6 +574,9 @@ func (s *Ethereum) Stop() error {
 	close(s.closeBloomHandler)
 	s.txPool.Stop()
 	s.miner.Stop()
+	s.miner.Close()
+	// TODO this is a hotfix for https://github.com/ethereum/go-ethereum/issues/22892, need a better solution
+	time.Sleep(5 * time.Second)
 	s.blockchain.Stop()
 	s.engine.Close()
 	rawdb.PopUncleanShutdownMarker(s.chainDb)