`WriteArray` involves reflection, it makes sense to optimize
serialization of transactions and application logs which are serialized
constantly. Adding case in a type switch in `WriteArray` is not an
option because we don't want new dependencies for `io` package.
```
name old time/op new time/op delta
AppExecResult_EncodeBinary-8 852ns ± 3% 656ns ± 2% -22.94% (p=0.000 n=10+9)
name old alloc/op new alloc/op delta
AppExecResult_EncodeBinary-8 448B ± 0% 376B ± 0% -16.07% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
AppExecResult_EncodeBinary-8 7.00 ± 0% 5.00 ± 0% -28.57% (p=0.000 n=10+10)
```
```
name old time/op new time/op delta
Transaction_Bytes-8 1.29µs ± 3% 0.76µs ± 5% -41.52% (p=0.000 n=9+10)
name old alloc/op new alloc/op delta
Transaction_Bytes-8 1.21kB ± 0% 1.01kB ± 0% -16.56% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
Transaction_Bytes-8 12.0 ± 0% 7.0 ± 0% -41.67% (p=0.000 n=10+10)
```
Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>
ReadArray() can return some error and we shouldn't overwrite it. At the same
time limiting ReadArray() to the number of Signers can make it return wrong
error if the number of witnesses actually is bigger than the number of
signers, so use MaxAttributes.
We burn GAS in OnPersist for every transaction so some buffer reuse here is
quite natural.
This also doesn't change a lot in the overall TPS picture, maybe adding some
1%.
Which duplicates the check, but deduplicates error path. This check forced
double balance deserialization which is quite costly operation, so we better
do it once.
It's hardly noticeable as of TPS metrics though, maybe some 1-2%%.
Persist by its definition doesn't change MemCachedStore visible state, all KV
pairs that were acessible via it before Persist remain accessible after
Persist. The only thing it does is flushing of the current set of KV pairs
from memory to peristent store. To do that it needs read-only access to the
current KV pair set, but technically it then replaces maps, so we have to use
full write lock which makes MemCachedStore inaccessible for the duration of
Persist. And Persist can take a lot of time, it's about disk access for
regular DBs.
What we do here is we create new in-memory maps for MemCachedStore before
flushing old ones to the persistent store. Then a fake persistent store is
created which actually is a MemCachedStore with old maps, so it has exactly
the same visible state. This Store is never accessed for writes, so we can
read it without taking any internal locks and at the same time we no longer
need write locks for original MemCachedStore, we're not using it. All of this
makes it possible to use MemCachedStore as normally reads are handled going
down to whatever level is needed and writes are handled by new maps. So while
Persist for (*Blockchain).dao does its most time-consuming work we can process
other blocks (reading data for transactions and persisting storeBlock caches
to (*Blockchain).dao).
The change was tested for performance with neo-bench (single node, 10 workers,
LevelDB) on two machines and block dump processing (RC4 testnet up to 62800
with VerifyBlocks set to false) on i7-8565U.
Reference results (bbe4e9cd7b):
Ryzen 9 5950X:
RPS 23616.969 22817.086 23222.378 ≈ 23218 ± 1.72%
TPS 23047.316 22608.578 22735.540 ≈ 22797 ± 0.99%
CPU % 23.434 25.553 23.848 ≈ 24.3 ± 4.63%
Mem MB 600.636 503.060 582.043 ≈ 562 ± 9.22%
Core i7-8565U:
RPS 6594.007 6499.501 6572.902 ≈ 6555 ± 0.76%
TPS 6561.680 6444.545 6510.120 ≈ 6505 ± 0.90%
CPU % 58.452 60.568 62.474 ≈ 60.5 ± 3.33%
Mem MB 234.893 285.067 269.081 ≈ 263 ± 9.75%
DB restore:
real 0m22.237s 0m23.471s 0m23.409s ≈ 23.04 ± 3.02%
user 0m35.435s 0m38.943s 0m39.247s ≈ 37.88 ± 5.59%
sys 0m3.085s 0m3.360s 0m3.144s ≈ 3.20 ± 4.53%
After the change:
Ryzen 9 5950X:
RPS 27747.349 27407.726 27520.210 ≈ 27558 ± 0.63% ↑ 18.69%
TPS 26992.010 26993.468 27010.966 ≈ 26999 ± 0.04% ↑ 18.43%
CPU % 28.928 28.096 29.105 ≈ 28.7 ± 1.88% ↑ 18.1%
Mem MB 760.385 726.320 756.118 ≈ 748 ± 2.48% ↑ 33.10%
Core i7-8565U:
RPS 7783.229 7628.409 7542.340 ≈ 7651 ± 1.60% ↑ 16.72%
TPS 7708.436 7607.397 7489.459 ≈ 7602 ± 1.44% ↑ 16.85%
CPU % 74.899 71.020 72.697 ≈ 72.9 ± 2.67% ↑ 20.50%
Mem MB 438.047 436.967 416.350 ≈ 430 ± 2.84% ↑ 63.50%
DB restore:
real 0m20.838s 0m21.895s 0m21.794s ≈ 21.51 ± 2.71% ↓ 6.64%
user 0m39.091s 0m40.565s 0m41.493s ≈ 40.38 ± 3.00% ↑ 6.60%
sys 0m3.184s 0m2.923s 0m3.062s ≈ 3.06 ± 4.27% ↓ 4.38%
It obviously uses more memory now and utilizes CPU more aggressively, but at
the same time it allows to improve all relevant metrics and finally reach a
situation where we process 50K transactions in less than second on Ryzen 9
5950X (going higher than 25K TPS). The other observation is much more stable
block time, on Ryzen 9 it's as close to 1 second as it could be.
Block processing consists of:
* saving block/transactions to the DB
* executing blocks/transactions
* processing notifications/saving AERs
* updating MPT
* atomically updating Blockchain state
Of these the first one is completely independent of others, it can be done in
a separate routine easily. The third one technically depends on the second,
it just doesn't have data until something is executed. At the same time it
doesn't affect future executions in any way, so we can offload
AER/notification processing to separate goroutine (while the main thread
proceeds with other transactions).
MPT update depends on all executions, so it can't be offloaded, but it can be
done concurrently to AER processing. And only the last thing actually needs
all previous ones to be finished, so it's a natural synchronization point.
So we spawn two additional routines and let the main one execute transactions
and update MPT as fast as it can. While technically all of these routines
could share single DAO (they are working with different KV sets) benchmarking
shows that using separate DAOs and then persisting them to lower one actually
works about 7-8%% better. At the same time we can simplify DAOs used, Cached
one is only relevant for AER processing because it caches NEP-17 tracking
data, everything else can do just fine with Simple.
The change was tested for performance with neo-bench (single node, 10 workers,
LevelDB) on two machines and block dump processing (RC4 testnet up to 50825
with VerifyBlocks set to false) on i7-8565U. neo-bench creates huge blocks
with lots of transactions while RC4 dump mostly consists of empty blocks.
Reference results (06c3dda5d1):
Ryzen 9 5950X:
RPS ≈ 20059.569 21186.328 20158.983 ≈ 20468 ± 3.05%
TPS ≈ 19544.993 20585.450 19658.338 ≈ 19930 ± 2.86%
CPU ≈ 18.682% 23.877% 22.852% ≈ 21.8 ± 12.62%
Mem ≈ 618.981MB 559.246MB 541.539MB ≈ 573 ± 7.08%
Core i7-8565U:
RPS ≈ 5927.082 6526.739 6372.115 ≈ 6275 ± 4.96%
TPS ≈ 5899.531 6477.187 6329.515 ≈ 6235 ± 4.81%
CPU ≈ 56.346% 61.955% 58.125% ≈ 58.8 ± 4.87%
Mem ≈ 212.191MB 224.974MB 205.479MB ≈ 214 ± 4.62%
DB restore:
real 0m12.683s 0m13.222s 0m13.382s ≈ 13.096 ± 2.80%
user 0m18.501s 0m19.163s 0m19.489s ≈ 19.051 ± 2.64%
sys 0m1.404s 0m1.396s 0m1.666s ≈ 1.489 ± 10.32%
After the change:
Ryzen 9 5950X:
RPS ≈ 23056.899 22822.015 23006.543 ≈ 22962 ± 0.54%
TPS ≈ 22594.785 22292.071 22800.857 ≈ 22562 ± 1.13%
CPU ≈ 24.262% 23.185% 25.921% ≈ 24.5 ± 5.65%
Mem ≈ 614.254MB 613.204MB 555.491MB ≈ 594 ± 5.66%
Core i7-8565U:
RPS ≈ 6378.702 6423.927 6363.788 ≈ 6389 ± 0.49%
TPS ≈ 6327.072 6372.552 6311.179 ≈ 6337 ± 0.50%
CPU ≈ 57.599% 58.622% 59.737% ≈ 58.7 ± 1.82%
Mem ≈ 198.697MB 188.746MB 200.235MB ≈ 196 ± 3.18%
DB restore:
real 0m13.576s 0m13.334s 0m12.757s ≈ 13.222 ± 3.18%
user 0m19.113s 0m19.490s 0m20.197s ≈ 19.600 ± 2.81%
sys 0m2.211s 0m1.558s 0m1.559s ≈ 1.776 ± 21.21%
On Ryzen 9 we've got 12% better RPS, 13% better TPS with 12% CPU and 3% RAM
more used. Core i7-8565U changes don't seem to be statistically significant:
1.8% more RPS, 1.6% more TPS with about the same CPU and 8.5% less RAM
used. It also is 1% worse in DB restore time.
The result is somewhat expected, on a powerful machine with lots of spare
cores we get 10%+ better results while on average resource-constrained laptop it
doesn't change much (the machine is already saturated). Overall, this seems to
be worthwhile.
If wallet size decreases, we need to remove trailing garbage if it
exists. This can happen when removing account or reading pretty-printed
wallet. It doesn't affect our CLI (we decode only file prefix), but
it is nice to always have a valid JSON file.
Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>
Request NEP17 balances from a set of NEP17 contracts instead of getting
them from storage. LastUpdatedBlock tracking remains untouched, because
there's no way to retrieve it dynamically.
Balances are to be removed from state.NEP17TransferInfo, so the remnant
fields are NextTransferBatch, NewBatch and a map of LastUpdatedBlocks.
These fields are more staff-related.
Also rename dao.[Get, Put, put]NEP17Balances and STNEP17Balances
preffix.
Also rename NEP17TransferInfo.Trackers to LastUpdatedBlockTrackers
because NEP17TransferInfo.Balances are to be removed.
