Chain simulations throws panic for certain seeds

[javiersuweijie]

When take rate is set too high in simulations, asset.TotalTokens decay too quickly such that there isn't enough tokens to calculate reward distribution.

Stacktrace

Simulating... block 153/200, operation 0/16.panic: failed to rebalance assets in x/alliance module: there are no delegations yet

goroutine 866 [running]:
github.com/terra-money/alliance/x/alliance.EndBlocker({{0x106c93848, 0x14000128008}, {0x106ca3360, 0x140224193c0}, {{0x0, 0x0}, {0x105b70a86, 0xe}, 0x99, {0x0, ...}, ...}, ...}, ...)
        /Users/javiersuweijie/go/pkg/mod/github.com/terra-money/[email protected]/x/alliance/abci.go:31 +0x35c
github.com/terra-money/alliance/x/alliance.AppModule.EndBlock(...)
        /Users/javiersuweijie/go/pkg/mod/github.com/terra-money/[email protected]/x/alliance/module.go:103
github.com/cosmos/cosmos-sdk/types/module.(*Manager).EndBlock(_, {{0x106c93848, 0x14000128008}, {0x106ca3360, 0x140224193c0}, {{0x0, 0x0}, {0x105b70a86, 0xe}, 0x99, ...}, ...}, ...)
        /Users/javiersuweijie/go/pkg/mod/github.com/terra-money/[email protected]/types/module/module.go:505 +0x1a4
github.com/terra-money/core/v2/app.(*TerraApp).EndBlocker(...)
        /Users/javiersuweijie/Projects/core/app/app.go:876
github.com/cosmos/cosmos-sdk/baseapp.(*BaseApp).EndBlock(0x14001098380, {0x14000128008?})
        /Users/javiersuweijie/go/pkg/mod/github.com/terra-money/[email protected]/baseapp/abci.go:206 +0x134
github.com/cosmos/cosmos-sdk/x/simulation.SimulateFromSeed({0x106ca8a00?, 0x1400013ca00}, {0x106c75640?, 0x14000126008}, 0x43e2cf?, 0x1090b63a0?, 0x106c65030, {0x140001e7180, 0x24, 0x28}, ...)
        /Users/javiersuweijie/go/pkg/mod/github.com/terra-money/[email protected]/x/simulation/simulate.go:188 +0x11b0
github.com/terra-money/core/v2/app_test.BenchmarkSimulation(0x1400013ca00)
        /Users/javiersuweijie/Projects/core/app/simulation_test.go:74 +0x420
testing.(*B).runN(0x1400013ca00, 0x1)
        /usr/local/go/src/testing/benchmark.go:193 +0x128
testing.(*B).run1.func1()
        /usr/local/go/src/testing/benchmark.go:233 +0x50
created by testing.(*B).run1
        /usr/local/go/src/testing/benchmark.go:226 +0x8c
exit status 2
FAIL    github.com/terra-money/core/v2/app      28.802s
FAIL

[javiersuweijie]

Running simulations in feather-core

 https://github.com/AaronCQL/feather-core. Running simulations with --Seed=51:
go test ./app --benchmem --run='^$' --bench='^BenchmarkSimulation' --NumBlocks=200 --BlockSize=30 --InitialBlockHeight=1 --Seed=51

Results in error:
simulate.go:302: error on block  67/200, operation (14/27) from x/alliance:
failed to execute message; message index: 0: rpc error: code = InvalidArgument desc = Cannot redelegate to the same validator [terra-money/[email protected]/baseapp/baseapp.go:799]
Comment: unable to deliver tx

Running with a large enough --NumBlocks and --BlockSize may sometimes also cause errors:

// This passes:
go test ./app --benchmem --run='^$' --bench='^BenchmarkSimulation' --NumBlocks=200 --BlockSize=30 --InitialBlockHeight=1 --Seed=1 

// This fails:
go test ./app --benchmem --run='^$' --bench='^BenchmarkSimulation' --NumBlocks=400 --BlockSize=50 --InitialBlockHeight=1 --Seed=1

// With this error:
Simulating... block 169/400, operation 0/3.panic: failed to rebalance assets in x/alliance module: there are no delegations yet