Each client submit same number of transactions in benchmark

Having widely different sequence length make interpretation of numbers
and graph difficult because the observed throughput and latency can
change dramatically if several clients stop feeding the nodes

hydra-node/src/Hydra/Ledger/Cardano.hs

@@ -268,6 +268,12 @@ genSequenceOfValidTransactions initialUtxo
   | otherwise = do
     n <- getSize
     numTxs <- choose (1, n)
+    genFixedSizeSequenceOfValidTransactions numTxs initialUtxo
+
+genFixedSizeSequenceOfValidTransactions :: Int -> Utxo CardanoTx -> Gen [CardanoTx]
+genFixedSizeSequenceOfValidTransactions numTxs initialUtxo
+  | initialUtxo == mempty = pure []
+  | otherwise = do
     reverse . snd <$> foldM newTx (initialUtxo, []) [1 .. numTxs]
  where
   newTx (utxos, acc) _ = do

local-cluster/bench/Bench/EndToEnd.hs

@@ -33,7 +33,7 @@ import Data.Set ((\\))
 import qualified Data.Set as Set
 import Data.Time (nominalDiffTimeToSeconds)
 import Hydra.Ledger (Tx, TxId, Utxo, txId)
-import Hydra.Ledger.Cardano (CardanoTx, genSequenceOfValidTransactions, genUtxo)
+import Hydra.Ledger.Cardano (CardanoTx, genFixedSizeSequenceOfValidTransactions, genUtxo)
 import Hydra.Logging (showLogsOnFailure)
 import HydraNode (
   HydraClient,
@@ -49,7 +49,7 @@ import HydraNode (
   withNewClient,
  )
 import System.FilePath ((</>))
-import Test.QuickCheck (generate, scale)
+import Test.QuickCheck (generate)
 import Text.Printf (printf)
 
 aliceSk, bobSk, carolSk :: SignKeyDSIGN MockDSIGN
@@ -69,9 +69,9 @@ data Dataset = Dataset
   deriving (Eq, Show, Generic, ToJSON, FromJSON)
 
 generateDataset :: Int -> IO Dataset
-generateDataset scalingFactor = do
+generateDataset sequenceLength = do
   initialUtxo <- generate genUtxo
-  transactionsSequence <- generate $ scale (* scalingFactor) $ genSequenceOfValidTransactions initialUtxo
+  transactionsSequence <- generate $ genFixedSizeSequenceOfValidTransactions sequenceLength initialUtxo
   pure Dataset{initialUtxo, transactionsSequence}
 
 data Event = Event

local-cluster/bench/Main.hs

@@ -25,6 +25,7 @@ import Options.Applicative (
 import System.Directory (createDirectory, doesDirectoryExist)
 import System.Environment (withArgs)
 import System.FilePath ((</>))
+import Test.QuickCheck (generate, getSize, scale)
 
 data Options = Options
   { outputDirectory :: Maybe FilePath
@@ -113,7 +114,8 @@ main =
     run timeoutSeconds benchDir datasets clusterSize
 
   play scalingFactor concurrency timeoutSeconds clusterSize benchDir = do
-    dataset <- replicateM concurrency (generateDataset scalingFactor)
+    numberOfTxs <- generate $ scale (* scalingFactor) getSize
+    dataset <- replicateM concurrency (generateDataset numberOfTxs)
     saveDataset benchDir dataset
     run timeoutSeconds benchDir dataset clusterSize