Problem: memiavl restore not fast enough (backport crypto-org-chain#1241

)

* Problem: memiavl restore not fast enough

Solution:
- increase channel buffer size to improve parallisation

it reduce restore time by 44% when testing with testnet, thanks @yzang2019 for sharing the finding.

* Update CHANGELOG.md

Signed-off-by: yihuang <huang@crypto.com>

* fix unit test

---------

Signed-off-by: yihuang <huang@crypto.com>

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- [#1241](https://github.com/crypto-org-chain/cronos/pull/1241) Improve parallelization of memiavl restoration.
+
 ### State Machine Breaking
 
 - [cronos#695](https://github.com/crypto-org-chain/cronos/pull/695) Implement ADR-007, generic events format with indexed params.

memiavl/import.go

@@ -17,6 +17,8 @@ import (
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 )
 
+const NodeChannelBuffer = 2048
+
 // Import restore memiavl db from state-sync snapshot stream
 func Import(
 	dir string, height uint64, format uint32, protoReader protoio.Reader,
@@ -116,7 +118,7 @@ type TreeImporter struct {
 }
 
 func NewTreeImporter(dir string, version int64) *TreeImporter {
-	nodesChan := make(chan *iavl.ExportNode)
+	nodesChan := make(chan *iavl.ExportNode, NodeChannelBuffer)
 	quitChan := make(chan error)
 	go func() {
 		defer close(quitChan)