Use a single client per node in benchmarks

[abailly-iohk]

A while ago we introduced the withNewClient function to submit transactions in the benchmark because we wanted to increase concurrency and be able to load the server with more than one client. We ended up dropping that capability from the benchmarks but kept having a separate connection between the main body of the benchmark and the transaction submission process.

This actually introduces a subtle bug that does only surface for sufficiently large loads. Here is what's happening:

1. The benchmark opens a connection to control the head
2. For each separate list of transaction in the workload, we open a connection and starts sending txs and reading results
3. Because all Server outputs are broadcast to all clients, the first connection is also sent the messages but does not read it
4. After a while, which depends on parameters of the machine, the TCP buffer is full and the TCP protocol triggers a close of the server -> client part of the connection
5. The client -> server part is still valid so the client can send the close once the transaction processing ends
6. But as soon as we want to receive something, we start reading stale messages accumulated in some buffer and then it the closed connection

---

• CHANGELOG updated or not needed
• Documentation updated or not needed
• Haddocks updated or not needed
• No new TODOs introduced or explained herafter

[github-actions]

Transactions Costs

Sizes and execution budgets for Hydra protocol transactions. Note that unlisted parameters are currently using arbitrary values and results are not fully deterministic and comparable to previous runs.

Metadata
Generated at	2023-06-06 17:13:02.347537111 UTC
Max. memory units	14000000
Max. CPU units	10000000000
Max. tx size (kB)	16384

Script summary

Name	Hash	Size (Bytes)
νInitial	2212a4ee618434b9b2f366d7c330dbdfb5c7072e793a850fd0de6ddd	4294
νCommit	69e1ccf9ad73dc6d37a5bc8de5aec86f3c4c1710fe5fd334e0e16b18	2124
νHead	8ae095dca4d14a1b8edffb37faa6c84ec60340fbf389a62f027e0b76	9355
μHead	33642a45c7fbb955ce1704ef09229bb211bf9af9980530db28c6aafe*	4148

• The minting policy hash is only usable for comparison. As the script is parameterized, the actual script is unique per Head.

Cost of Init Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	4739	13.97	5.49	0.51
2	4947	16.27	6.35	0.55
3	5152	19.50	7.61	0.59
5	5559	22.97	8.86	0.64
10	6587	36.20	13.91	0.83
37	12123	97.09	36.76	1.73

Cost of Commit Transaction

This is using ada-only outputs for better comparability.

UTxO	Tx size	% max Mem	% max CPU	Min fee ₳
1	596	14.98	5.74	0.34
2	784	19.57	7.70	0.40
3	970	24.66	9.84	0.46
5	1350	36.07	14.56	0.61
10	2280	71.73	28.85	1.04
13	2846	98.03	39.15	1.35

Cost of CollectCom Transaction

Parties	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
1	57	814	27.93	10.85	0.49
2	114	1142	43.16	16.89	0.67
3	170	1455	61.97	24.41	0.89
4	225	1783	82.10	32.49	1.13

Cost of Close Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	640	18.88	8.42	0.39
2	671	17.76	7.45	0.38
3	969	21.67	10.94	0.45
5	1299	24.46	13.45	0.50
10	2120	31.42	19.73	0.64
50	8725	86.87	69.87	1.74

Cost of Contest Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	676	24.34	10.47	0.45
2	833	26.49	12.01	0.49
3	1006	27.77	13.21	0.51
5	1335	31.20	15.95	0.58
10	2168	40.20	22.97	0.74
45	7928	99.74	70.74	1.81

Cost of Abort Transaction

Some variation because of random mixture of still initial and already committed outputs.

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	4857	22.45	9.40	0.61
2	5174	36.59	15.53	0.79
3	5496	53.73	22.99	0.99
4	5817	73.63	31.65	1.23
5	6142	95.94	41.43	1.49

Cost of FanOut Transaction

Involves spending head output and burning head tokens. Uses ada-only UTxO for better comparability.

Parties	UTxO	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
5	0	0	4769	8.66	3.57	0.46
5	1	57	4801	10.06	4.39	0.47
5	5	285	4945	15.64	7.69	0.55
5	10	569	5120	22.61	11.82	0.64
5	20	1137	5481	36.56	20.07	0.83
5	30	1708	5845	50.52	28.33	1.02
5	40	2279	6209	64.49	36.60	1.21
5	50	2847	6567	78.46	44.87	1.40
5	65	3700	7101	99.42	57.28	1.68

[github-actions]

Test Results

319 tests  +11   313 ✔️ +11   19m 28s ⏱️ + 1m 5s
108 suites +  4       6 💤 ±  0 
    6 files   +  1       0 ❌ ±  0 

Results for commit b1cc6b5. ± Comparison against base commit 70a9967.