Fix getting the start time so the first block is no longer empty

tools/tm-bench/README.md

@@ -51,15 +51,26 @@ with the last command being in a seperate window.
 ## How stats are collected
 
 These stats are derived by having each connection send transactions at the
-specified rate (or as close as it can get) for the specified time. After the
-specified time, it iterates over all of the blocks that were created in that
-time. The average and stddev per second are computed based off of that, by
+specified rate (or as close as it can get) for the specified time.
+After the specified time, it iterates over all of the blocks that were created
+in that time.
+The average and stddev per second are computed based off of that, by
 grouping the data by second.
 
 To send transactions at the specified rate in each connection, we loop
-through the number of transactions. If its too slow, the loop stops at one second.
-If its too fast, we wait until the one second mark ends. The transactions per
-second stat is computed based off of what ends up in the block.
+through the number of transactions.
+If its too slow, the loop stops at one second.
+If its too fast, we wait until the one second mark ends.
+The transactions per second stat is computed based off of what ends up in the
+block.
+
+Note that there will be edge effects on the number of transactions in the first
+and last blocks.
+This is because transactions may start sending midway through when tendermint
+starts building the next block, so it only has half as much time to gather txs
+that tm-bench sends.
+Similarly the end of the duration will likely end mid-way through tendermint
+trying to build the next block.
 
 Each of the connections is handled via two separate goroutines. 
 

tools/tm-bench/main.go

@@ -101,7 +101,20 @@ Examples:
 		"broadcast_tx_"+broadcastTxMethod,
 	)
 
-	// record time start
+	// Wait until transacters have begun until we get the start time
+	for {
+		started := true
+		for _, t := range transacters {
+			for i := 0; i < t.Connections; i++ {
+				if !t.connsStarted[i] && !t.connsBroken[i] {
+					started = false
+				}
+			}
+		}
+		if started {
+			break
+		}
+	}
 	timeStart := time.Now()
 	logger.Info("Time last transacter started", "t", timeStart)
 

tools/tm-bench/transacter.go

@@ -34,10 +34,11 @@ type transacter struct {
 	Connections       int
 	BroadcastTxMethod string
 
-	conns       []*websocket.Conn
-	connsBroken []bool
-	wg          sync.WaitGroup
-	stopped     bool
+	conns        []*websocket.Conn
+	connsStarted []bool
+	connsBroken  []bool
+	wg           sync.WaitGroup
+	stopped      bool
 
 	logger log.Logger
 }
@@ -50,6 +51,7 @@ func newTransacter(target string, connections, rate int, size int, broadcastTxMe
 		Connections:       connections,
 		BroadcastTxMethod: broadcastTxMethod,
 		conns:             make([]*websocket.Conn, connections),
+		connsStarted:      make([]bool, connections),
 		connsBroken:       make([]bool, connections),
 		logger:            log.NewNopLogger(),
 	}
@@ -156,6 +158,7 @@ func (t *transacter) sendLoop(connIndex int) {
 			startTime := time.Now()
 			endTime := startTime.Add(time.Second)
 			numTxSent := t.Rate
+			t.connsStarted[connIndex] = true
 
 			for i := 0; i < t.Rate; i++ {
 				// each transaction embeds connection index, tx number and hash of the hostname