Don't write back to the same input we read from; seems to cause deadlock

[noonio]

@ffakenz can you write a little bit about this change?

• Fixes Node stuck in ReplayingState #2089

Also related to #2086, but we don't expect this to completely resolve that problem.

[github-actions]

Transaction 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	2025-06-26 15:30:10.27908713 UTC
Max. memory units	14000000
Max. CPU units	10000000000
Max. tx size (kB)	16384

Script summary

Name	Hash	Size (Bytes)
νInitial	c8a101a5c8ac4816b0dceb59ce31fc2258e387de828f02961d2f2045	2652
νCommit	61458bc2f297fff3cc5df6ac7ab57cefd87763b0b7bd722146a1035c	685
νHead	be6ebc744208c660bf0fdc1cfbb5157477cd305de5b1777e575cbb4c	14665
μHead	1f47a42d1d6edc32ccd834acb19d5db3b2a5232f0bd7eaa8908dc519*	5284
νDeposit	ae01dade3a9c346d5c93ae3ce339412b90a0b8f83f94ec6baa24e30c	1102

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

Init transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	5836	10.56	3.35	0.52
2	6038	12.67	4.02	0.55
3	6238	14.26	4.50	0.57
5	6640	18.97	6.00	0.64
10	7647	29.35	9.26	0.79
43	14283	98.94	30.92	1.80

Commit transaction costs

This uses ada-only outputs for better comparability.

UTxO	Tx size	% max Mem	% max CPU	Min fee ₳
1	561	2.44	1.16	0.20
2	743	3.38	1.73	0.22
3	920	4.36	2.33	0.24
5	1273	6.41	3.60	0.28
10	2173	12.13	7.25	0.40
54	10055	98.61	68.52	1.88

CollectCom transaction costs

Parties	UTxO (bytes)	Tx size	% max Mem	% max CPU	Min fee ₳
1	57	525	25.24	7.32	0.43
2	113	640	34.38	9.91	0.53
3	171	747	40.14	11.65	0.59
4	225	858	49.50	14.27	0.69
5	284	969	57.39	16.55	0.78
6	339	1081	71.70	20.44	0.92
7	394	1192	74.59	21.53	0.96
8	448	1303	91.55	25.94	1.13
9	507	1418	89.52	26.02	1.12

Cost of Increment Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	1748	22.83	7.57	0.47
2	1938	25.69	9.18	0.51
3	2147	28.88	11.00	0.56
5	2383	31.12	12.96	0.60
10	3110	39.23	18.97	0.74
42	7909	99.98	60.07	1.74

Cost of Decrement Transaction

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	607	22.73	7.33	0.41
2	692	22.51	7.91	0.42
3	874	24.94	9.26	0.46
5	1179	28.96	11.72	0.52
10	1958	38.45	17.73	0.67
41	6535	97.04	54.66	1.62

Close transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	697	27.33	8.80	0.47
2	891	29.66	10.30	0.50
3	971	33.10	11.95	0.55
5	1264	37.37	14.69	0.61
10	2105	45.06	20.78	0.76
37	6126	98.76	56.40	1.62

Contest transaction costs

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	679	33.70	10.50	0.53
2	768	35.06	11.48	0.55
3	1007	38.41	13.37	0.60
5	1417	43.66	16.52	0.68
10	2104	53.67	22.98	0.84
30	4822	97.53	49.86	1.51

Abort transaction costs

There is some variation due to the random mixture of initial and already committed outputs.

Parties	Tx size	% max Mem	% max CPU	Min fee ₳
1	5791	26.89	9.02	0.69
2	5961	36.68	12.35	0.80
3	6015	44.26	14.82	0.88
4	6242	55.64	18.67	1.01
5	6269	62.22	20.80	1.08
6	6308	70.47	23.53	1.17
7	6542	81.46	27.30	1.29
8	6778	91.83	30.87	1.41
9	6708	93.35	31.23	1.42

FanOut transaction costs

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 ₳
10	0	0	5835	19.19	6.41	0.61
10	1	57	5868	22.11	7.52	0.64
10	20	1139	6514	59.57	22.38	1.08
10	30	1709	6856	80.53	30.62	1.32
10	38	2163	7126	97.13	37.15	1.52

End-to-end benchmark results

This page is intended to collect the latest end-to-end benchmark results produced by Hydra's continuous integration (CI) system from the latest master code.

Please note that these results are approximate as they are currently produced from limited cloud VMs and not controlled hardware. Rather than focusing on the absolute results, the emphasis should be on relative results, such as how the timings for a scenario evolve as the code changes.

Generated at 2025-06-26 15:32:58.626288353 UTC

Baseline Scenario

Number of nodes	1
Number of txs	300
Avg. Confirmation Time (ms)	4.542773983
P99	8.973801159999988ms
P95	5.451819950000002ms
P50	4.345498ms
Number of Invalid txs	0

Memory data

Time	Used	Free
2025-06-26 15:31:41.801036601 UTC	0m	0;
2025-06-26 15:31:46.800882755 UTC	2	0;
2025-06-26 15:31:51.801128403 UTC	7	0;
2025-06-26 15:31:56.800936685 UTC	1	0;
2025-06-26 15:32:01.800981333 UTC	1	0;
2025-06-26 15:32:06.800967919 UTC	1	0;

Three local nodes

Number of nodes	3
Number of txs	900
Avg. Confirmation Time (ms)	30.292866520
P99	45.84901367ms
P95	40.6053948ms
P50	29.1562025ms
Number of Invalid txs	0

Memory data

Time	Used	Free
2025-06-26 15:32:20.810618794 UTC	0m	0;
2025-06-26 15:32:25.81059166 UTC	2	0;
2025-06-26 15:32:30.813464418 UTC	4	0;
2025-06-26 15:32:35.810580646 UTC	20	0;
2025-06-26 15:32:40.810606601 UTC	20	0;
2025-06-26 15:32:45.810567135 UTC	3	0;
2025-06-26 15:32:50.810565994 UTC	3	0;
2025-06-26 15:32:55.81059017 UTC	2	0;

[github-actions]

Transaction cost differences

No cost or size differences found