Benchmark: Check to Skip

Sometimes, you just need to check whether a collection is empty or null to skip execution. But how expensive is that?

This very simple benchmark tested some ways to do this:

AntonioFalcaoJr / Benchmark

Sometimes, you just need to check whether a collection is empty or null to skip execution. But how expensive is that?

Scenarios

// SCENARIO 1
    var list = Ids?.ToList() ?? new List<Guid>();
    if (list.Any() is false) { }

// SCENARIO 2
    var list = Ids?.ToArray() ?? Array.Empty<Guid>();
    if (list.Any() is false) { }

// SCENARIO 3
    // toList(); 
    var list = _ids?.ToList();
    if (list is null || list.Any() is false) { }
    // toArray();
    var list = _ids?.ToArray();
    if (list is null || list.Any() is false) { }

// SCENARIO 4
    // toList();
    var list = Ids?.ToList();
    if (list is {Count: > 0} is false) { }
    // toArray();
    var list = _ids?.ToArray();
    if (list is {Length: > 0} is false) { }

// SCENARIO 5
    // toList();
    var list = Ids?.ToList();
    if (list?.Count <= 0) { }
    // toArray();
    var list = _ids?.ToArray();
    if (list?.Length <= 0) { }

Result

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.18363.1198 (1909/November2018Update/19H2)
Intel Core i7-9700 CPU 3.00GHz, 1 CPU, 8 logical and 8 physical cores
.NET Core SDK=5.0.101
  [Host]        : .NET Core 5.0.1 (CoreCLR 5.0.120.57516, CoreFX 5.0.120.57516), X64 RyuJIT
  .NET Core 3.1 : .NET Core 3.1.10 (CoreCLR 4.700.20.51601, CoreFX 4.700.20.51901), X64 RyuJIT
  .NET Core 5.0 : .NET Core 5.0.1 (CoreCLR 5.0.120.57516, CoreFX 5.0.120.57516), X64 RyuJIT

Method	Runtime	Mean	Error	StdDev	Ratio	RatioSD
Scenario1	Core 3.1	25.0384ns	0.5082ns	0.5649ns	2.64	0.06
Scenario1	.NET Core 5.0	9.5186ns	0.1186ns	0.1109ns	1.00	0.00
Scenario2	Core 3.1	7.0908ns	0.0687ns	0.0537ns	0.63	0.00
Scenario2	.NET 5	11.2512ns	0.0510ns	0.0426ns	1.00	0.00
Scenario3 toList	Core 3.1	0.4756ns	0.0099ns	0.0093ns	0.85	0.04
Scenario3 toList	.NET 5	0.5622ns	0.0278ns	0.0246ns	1.00	0.00
Scenario3 toArray	Core 3.1	0.4801ns	0.0074ns	0.0069ns	0.99	0.02
Scenario3 toArray	.NET 5	0.4854ns	0.0108ns	0.0101ns	1.00	0.00
Scenario4 toList	Core 3.1	0.2452ns	0.0024ns	0.0022ns	1.14	0.03
Scenario4 toList	.NET 5	0.2164ns	0.0058ns	0.0045ns	1.00	0.00
Scenario4 toArray	Core 3.1	0.4812ns	0.0082ns	0.0064ns	0.99	0.03
Scenario4 toArray	.NET 5	0.4856ns	0.0119ns	0.0111ns	1.00	0.00
Scenario5 toList	Core 3.1	0.2381ns	0.0060ns	0.0050ns	1.06	0.06
Scenario5 toList	.NET 5	0.2255ns	0.0166ns	0.0129ns	1.00	0.00
Scenario5 toArray	Core 3.1	0.6015ns	0.0365ns	0.0391ns	1.26	0.10
Scenario5 toArray	.NET 5	0.4802ns	0.0115ns	0.0107ns	1.00	0.00

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Hints

Outliers

Scenarios.Scenario1: .NET Core 3.1         -> 1 outlier  was  removed (29.51 ns)
Scenarios.Scenario2: .NET Core 3.1         -> 3 outliers were removed (8.72 ns..8.88 ns)
Scenarios.Scenario2: .NET Core 5.0         -> 2 outliers were removed (12.83 ns, 13.51 ns)
Scenarios.Scenario3_toList: .NET Core 5.0  -> 1 outlier  was  removed (2.01 ns)
Scenarios.Scenario4_toList: .NET Core 5.0  -> 3 outliers were removed (1.65 ns..1.67 ns)
Scenarios.Scenario4_toArray: .NET Core 3.1 -> 3 outliers were removed (1.87 ns..1.93 ns)
Scenarios.Scenario5_toList: .NET Core 3.1  -> 2 outliers were removed (1.64 ns, 1.65 ns)
Scenarios.Scenario5_toList: .NET Core 5.0  -> 3 outliers were removed (1.65 ns..1.68 ns)
Scenarios.Scenario5_toArray: .NET Core 3.1 -> 1 outlier  was  removed (2.08 ns)

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Legends

Mean    : Arithmetic mean of all measurements
Error   : Half of 99.9% confidence interval
StdDev  : Standard deviation of all measurements
Ratio   : Mean of the ratio distribution ([Current]/[Baseline])
RatioSD : Standard deviation of the ratio distribution ([Current]/[Baseline])
1 ns    : 1 Nanosecond (0.000000001 sec)