This tool makes it easy to run parachain consensus stress/performance
testing on your development machine or in CI.
## Motivation
The parachain consensus node implementation spans across many modules
which we call subsystems. Each subsystem is responsible for a small part
of logic of the parachain consensus pipeline, but in general the most
load and performance issues are localized in just a few core subsystems
like `availability-recovery`, `approval-voting` or
`dispute-coordinator`. In the absence of such a tool, we would run large
test nets to load/stress test these parts of the system. Setting up and
making sense of the amount of data produced by such a large test is very
expensive, hard to orchestrate and is a huge development time sink.
## PR contents
- CLI tool
- Data Availability Read test
- reusable mockups and components needed so far
- Documentation on how to get started
### Data Availability Read test
An overseer is built with using a real `availability-recovery` susbsytem
instance while dependent subsystems like `av-store`, `network-bridge`
and `runtime-api` are mocked. The network bridge will emulate all the
network peers and their answering to requests.
The test is going to be run for a number of blocks. For each block it
will generate send a “RecoverAvailableData” request for an arbitrary
number of candidates. We wait for the subsystem to respond to all
requests before moving to the next block.
At the same time we collect the usual subsystem metrics and task CPU
metrics and show some nice progress reports while running.
### Here is how the CLI looks like:
```
[2023-11-28T13:06:27Z INFO subsystem_bench::core::display] n_validators = 1000, n_cores = 20, pov_size = 5120 - 5120, error = 3, latency = Some(PeerLatency { min_latency: 1ms, max_latency: 100ms })
[2023-11-28T13:06:27Z INFO subsystem-bench::availability] Generating template candidate index=0 pov_size=5242880
[2023-11-28T13:06:27Z INFO subsystem-bench::availability] Created test environment.
[2023-11-28T13:06:27Z INFO subsystem-bench::availability] Pre-generating 60 candidates.
[2023-11-28T13:06:30Z INFO subsystem-bench::core] Initializing network emulation for 1000 peers.
[2023-11-28T13:06:30Z INFO subsystem-bench::availability] Current block 1/3
[2023-11-28T13:06:30Z INFO substrate_prometheus_endpoint] 〽️ Prometheus exporter started at 127.0.0.1:9999
[2023-11-28T13:06:30Z INFO subsystem_bench::availability] 20 recoveries pending
[2023-11-28T13:06:37Z INFO subsystem_bench::availability] Block time 6262ms
[2023-11-28T13:06:37Z INFO subsystem-bench::availability] Sleeping till end of block (0ms)
[2023-11-28T13:06:37Z INFO subsystem-bench::availability] Current block 2/3
[2023-11-28T13:06:37Z INFO subsystem_bench::availability] 20 recoveries pending
[2023-11-28T13:06:43Z INFO subsystem_bench::availability] Block time 6369ms
[2023-11-28T13:06:43Z INFO subsystem-bench::availability] Sleeping till end of block (0ms)
[2023-11-28T13:06:43Z INFO subsystem-bench::availability] Current block 3/3
[2023-11-28T13:06:43Z INFO subsystem_bench::availability] 20 recoveries pending
[2023-11-28T13:06:49Z INFO subsystem_bench::availability] Block time 6194ms
[2023-11-28T13:06:49Z INFO subsystem-bench::availability] Sleeping till end of block (0ms)
[2023-11-28T13:06:49Z INFO subsystem_bench::availability] All blocks processed in 18829ms
[2023-11-28T13:06:49Z INFO subsystem_bench::availability] Throughput: 102400 KiB/block
[2023-11-28T13:06:49Z INFO subsystem_bench::availability] Block time: 6276 ms
[2023-11-28T13:06:49Z INFO subsystem_bench::availability]
Total received from network: 415 MiB
Total sent to network: 724 KiB
Total subsystem CPU usage 24.00s
CPU usage per block 8.00s
Total test environment CPU usage 0.15s
CPU usage per block 0.05s
```
### Prometheus/Grafana stack in action
<img width="1246" alt="Screenshot 2023-11-28 at 15 11 10"
src="https://github.com/paritytech/polkadot-sdk/assets/54316454/eaa47422-4a5e-4a3a-aaef-14ca644c1574">
<img width="1246" alt="Screenshot 2023-11-28 at 15 12 01"
src="https://github.com/paritytech/polkadot-sdk/assets/54316454/237329d6-1710-4c27-8f67-5fb11d7f66ea">
<img width="1246" alt="Screenshot 2023-11-28 at 15 12 38"
src="https://github.com/paritytech/polkadot-sdk/assets/54316454/a07119e8-c9f1-4810-a1b3-f1b7b01cf357">
---------
Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>
Collators were previously reencoding the available data and checking the
erasure root.
Replace that with just checking the PoV hash, which consumes much less
CPU and takes less time.
We also don't need to check the `PersistedValidationData` hash, as
collators don't use it.
Reason:
https://github.com/paritytech/polkadot-sdk/issues/575#issuecomment-1806572230
After systematic chunks recovery is merged, collators will no longer do
any reed-solomon encoding/decoding, which has proven to be a great CPU
consumer.
Signed-off-by: alindima <alin@parity.io>
Refactors availability-recovery strategies to allow for easily adding
new hotpaths and failover mechanisms.
The new interface allows for chaining multiple `RecoveryStrategy`-es
together, to cleanly express the relationship between them and share
state and code where neccessary/possible:
This was done in order to aid in implementing new hotpaths like
[systematic chunks
recovery](https://github.com/paritytech/polkadot-sdk/issues/598) and
[fetching from approval
checkers](https://github.com/paritytech/polkadot-sdk/issues/575).
Thanks to this design, intermediate state can be shared between the
strategies. For example, if the systematic chunks recovery retrieved
less than the needed amount of chunks, pass them over to the next
FetchChunks strategy, which will only need to recover the remaining
number of chunks.
Draft example of how a systematic chunk recovery strategy would look:
https://github.com/paritytech/polkadot-sdk/commit/667d870bdf1470525d66c13929d5eac7249dd995
(notice how easy it was to add and reuse code)
Note that this PR doesn't itself add any new strategy, it should fully
preserve backwards compatiblity in terms of functionality. Follow-up PRs
to add new strategies will come.
Andrei Sandu