From d369f542c5d881879e37e968493b3fba7ac3d9fb Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Wed, 9 Sep 2020 23:17:09 +0300
Subject: [PATCH] warn when optimal selection fails to pack a block and we fall
 back to random selection

---
 chain/messagepool/selection.go | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/chain/messagepool/selection.go b/chain/messagepool/selection.go
index 8bb32eb1d..2ddbed0ad 100644
--- a/chain/messagepool/selection.go
+++ b/chain/messagepool/selection.go
@@ -309,8 +309,10 @@ tailLoop:
 
 	// if we have gasLimit to spare, pick some random (non-negative) chains to fill the block
 	// we pick randomly so that we minimize the probability of duplication among all miners
-	startRandom := time.Now()
 	if gasLimit >= minGas {
+		randomCount := 0
+
+		startRandom := time.Now()
 		shuffleChains(chains)
 
 		for _, chain := range chains {
@@ -359,15 +361,23 @@ tailLoop:
 				curChain := chainDeps[i]
 				curChain.merged = true
 				result = append(result, curChain.msgs...)
+				randomCount += len(curChain.msgs)
 			}
 
 			chain.merged = true
 			result = append(result, chain.msgs...)
+			randomCount += len(chain.msgs)
 			gasLimit -= chainGasLimit
 		}
-	}
-	if dt := time.Since(startRandom); dt > time.Millisecond {
-		log.Infow("pack random tail chains done", "took", dt)
+
+		if dt := time.Since(startRandom); dt > time.Millisecond {
+			log.Infow("pack random tail chains done", "took", dt)
+		}
+
+		if randomCount > 0 {
+			log.Warnf("optimal selection failed to pack a block; picked %d messages with random selection",
+				randomCount)
+		}
 	}
 
 	return result, nil