consensus: flush wal on stop (#3297)

Should fix #3295
Also partial fix of #3043

Author: ebuchman

CHANGELOG.md

@@ -89,7 +89,7 @@ Special thanks to external contributors on this release:
 - [p2p] [\#3247](https://github.com/tendermint/tendermint/issues/3247) Fix panic in SeedMode when calling FlushStop and OnStop
   concurrently
 - [p2p] [\#3040](https://github.com/tendermint/tendermint/issues/3040) Fix MITM on secret connection by checking low-order points
-- [privval] [\#3258](https://github.com/tendermint/tendermint/issues/3258) Fix race between sign requests and ping requests in socket
+- [privval] [\#3258](https://github.com/tendermint/tendermint/issues/3258) Fix race between sign requests and ping requests in socket that was causing messages to be corrupted
 
 ## v0.29.1
 

CHANGELOG_PENDING.md

@@ -21,3 +21,5 @@ Special thanks to external contributors on this release:
 ### IMPROVEMENTS:
 
 ### BUG FIXES:
+- [consensus] \#3297 Flush WAL on stop to prevent data corruption during
+  graceful shutdown

consensus/wal.go

@@ -116,6 +116,7 @@ func (wal *baseWAL) OnStart() error {
 // Use Wait() to ensure it's finished shutting down
 // before cleaning up files.
 func (wal *baseWAL) OnStop() {
+	wal.group.Flush()
 	wal.group.Stop()
 	wal.group.Close()
 }