Add support for ISpanFormattable in StringBuilder.Append(Object) #92197

manandre · 2023-09-17T20:50:49Z

Applying the optimization for ISpanFormattable, already implemented in AppendFormat, to Append.

src/libraries/System.Private.CoreLib/src/System/Text/StringBuilder.cs

stephentoub · 2023-09-18T13:57:41Z

Applying the optimization for ISpanFormattable, already implemented in AppendFormat, to Append.

Note that AppendFormatted is different. It's generic, which means thanks to generic specialization, we don't pay this check for value types; it evaporates completely in optimized code when the T is a struct. That's not the case here for Append(object), which means we'll be paying for the interface check more often.

stephentoub · 2023-09-18T15:31:03Z

Or we don't want to impact the performance when the object doesn't implement ISpanFormattable?

That's the concern. I'm not saying we can't do this, just that there is a cost associated with it, and we need to validate the perf on the common case where it doesn't implement the interface.

manandre · 2023-09-18T19:21:59Z

I am going to setup a benchmark to evaluate such impact for use cases with and without objects implementing ISpanFormattable.
It seems it won't be easy as dotnet/performance still does not support .NET 9.

manandre · 2023-10-05T21:38:18Z

I have benchmarked the changes to the StringBuilder.Append(object?) method.
Benchmark code: dotnet/performance@main...manandre:performance:sb-append-object
Benchmark results (where not Same):

Method	data	Ratio	MannWhitney(5%)	Alloc Ratio	Total Ratio
Append_ValueTypes		1.25	Slower	0.76	0.95
Append_Object	null	4.03	Slower	1.00	4.03
Append_Object	Char : A	1.11	Slower	0.21	0.23
Append_Object	Int32 : 42	1.75	Slower	1.00	1.75
Append_Object	Rune : A	0.98	Same	0.21	0.21
Append_Object	String :	2.39	Slower	1.00	2.39
Append_Object	String : 1234567890	1.28	Slower	1.00	1.28
Append_Object	Version : 1.2.3.4	0.95	Same	0.56	0.53

We should maybe put the null check in first place in the switch order to reduce the impact of the change.
Globally, the duration impact is quite important but I do not know how to compare it against the allocation gain.
I have computed a Total ratio (= Ratio * Alloc Ratio) as a naive metric.
Moreover, it is difficult to estimate the "weight" of each use case...

@stephentoub Can you please help here?

Benchmark summary

BenchmarkDotNet v0.13.9-nightly.20230908.70, Windows 10 (10.0.19045.3448/22H2/2022Update)
Intel Core i7-4770K CPU 3.50GHz (Haswell), 1 CPU, 8 logical and 4 physical cores
.NET SDK 8.0.100-rc.1.23463.5
[Host] : .NET 8.0.0 (8.0.23.41904), X64 RyuJIT AVX2
Job-MABLYB : .NET 8.0.0 (42.42.42.42424), X64 RyuJIT AVX2
Job-DFWZBP : .NET 8.0.0 (42.42.42.42424), X64 RyuJIT AVX2

PowerPlanMode=00000000-0000-0000-0000-000000000000 Arguments=/p:EnableUnsafeBinaryFormatterSerialization=true IterationTime=250.0000 ms
MaxIterationCount=20 MinIterationCount=15 WarmupCount=1

Method	Job	Toolchain	repeat	length	data	Mean	Error	StdDev	Median	Min	Max	Ratio	MannWhitney(5%)	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
AppendLine_Strings	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	174.45 ns	0.875 ns	0.776 ns	174.60 ns	173.09 ns	175.42 ns	1.00	Base	0.00	0.3074	-	-	1288 B	1.00
AppendLine_Strings	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	173.30 ns	0.644 ns	0.602 ns	173.06 ns	172.44 ns	174.45 ns	0.99	Same	0.01	0.3073	-	-	1288 B	1.00

Append_Primitives	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	871.61 ns	4.007 ns	3.748 ns	871.59 ns	865.47 ns	878.13 ns	1.00	Base	0.00	0.2615	-	-	1096 B	1.00
Append_Primitives	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	881.18 ns	6.783 ns	5.664 ns	879.61 ns	873.53 ns	889.82 ns	1.01	Same	0.01	0.2621	-	-	1096 B	1.00

Append_ValueTypes	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	1,470.36 ns	15.379 ns	13.633 ns	1,468.94 ns	1,454.33 ns	1,505.18 ns	1.00	Base	0.00	0.7488	-	-	3152 B	1.00
Append_ValueTypes	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	1,843.18 ns	7.217 ns	6.398 ns	1,843.02 ns	1,826.14 ns	1,854.63 ns	1.25	Slower	0.01	0.5756	-	-	2408 B	0.76

Append_ValueTypes_Interpolated	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	1,633.49 ns	11.670 ns	10.345 ns	1,636.03 ns	1,621.15 ns	1,655.19 ns	1.00	Base	0.00	0.3767	-	-	1584 B	1.00
Append_ValueTypes_Interpolated	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	1,760.95 ns	73.500 ns	84.643 ns	1,748.46 ns	1,645.36 ns	1,965.16 ns	1.10	Same	0.05	0.3776	-	-	1584 B	1.00

Append_Memory	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	419.87 ns	2.690 ns	2.384 ns	419.76 ns	416.05 ns	425.41 ns	1.00	Base	0.00	0.8681	-	-	3632 B	1.00
Append_Memory	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	414.48 ns	2.117 ns	1.981 ns	414.63 ns	411.10 ns	417.69 ns	0.99	Same	0.00	0.8674	-	-	3632 B	1.00

Append_NonEmptySpan	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	383.87 ns	2.111 ns	1.871 ns	383.80 ns	380.91 ns	387.43 ns	1.00	Base	0.00	0.8676	-	-	3632 B	1.00
Append_NonEmptySpan	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	380.07 ns	2.956 ns	2.469 ns	380.36 ns	377.30 ns	385.45 ns	0.99	Same	0.01	0.8677	-	-	3632 B	1.00

Insert_Primitives	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	27,965.09 ns	128.254 ns	119.968 ns	27,938.07 ns	27,837.08 ns	28,234.74 ns	1.00	Base	0.00	2.4510	-	-	10416 B	1.00
Insert_Primitives	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	28,213.10 ns	84.678 ns	79.208 ns	28,234.20 ns	28,112.17 ns	28,328.15 ns	1.01	Same	0.00	2.4686	-	-	10416 B	1.00

Insert_Strings	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	?	487.55 ns	2.621 ns	2.452 ns	487.78 ns	484.04 ns	491.64 ns	1.00	Base	0.00	0.3170	-	-	1328 B	1.00
Insert_Strings	Job-DFWZBP	\8.0.0\corerun.exe	?	?	?	509.14 ns	5.319 ns	4.975 ns	508.02 ns	501.35 ns	519.57 ns	1.04	Same	0.01	0.3173	-	-	1328 B	1.00

Append_Strings	Job-MABLYB	\8.0.0-ref\corerun.exe	1	?	?	158.31 ns	0.792 ns	0.741 ns	158.21 ns	156.94 ns	159.44 ns	1.00	Base	0.00	0.2984	-	-	1248 B	1.00
Append_Strings	Job-DFWZBP	\8.0.0\corerun.exe	1	?	?	159.40 ns	0.920 ns	0.861 ns	159.20 ns	158.37 ns	161.07 ns	1.01	Same	0.01	0.2981	-	-	1248 B	1.00

ctor_string	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100	?	29.40 ns	0.169 ns	0.150 ns	29.35 ns	29.13 ns	29.67 ns	1.00	Base	0.00	0.0649	-	-	272 B	1.00
ctor_string	Job-DFWZBP	\8.0.0\corerun.exe	?	100	?	29.37 ns	0.141 ns	0.125 ns	29.36 ns	29.17 ns	29.61 ns	1.00	Same	0.00	0.0649	-	-	272 B	1.00

ctor_capacity	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100	?	21.80 ns	0.104 ns	0.097 ns	21.83 ns	21.59 ns	21.93 ns	1.00	Base	0.00	0.0650	-	-	272 B	1.00
ctor_capacity	Job-DFWZBP	\8.0.0\corerun.exe	?	100	?	21.63 ns	0.089 ns	0.079 ns	21.63 ns	21.48 ns	21.77 ns	0.99	Same	0.01	0.0650	-	-	272 B	1.00

ToString_SingleSegment	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100	?	21.12 ns	0.103 ns	0.091 ns	21.12 ns	21.00 ns	21.25 ns	1.00	Base	0.00	0.0535	-	-	224 B	1.00
ToString_SingleSegment	Job-DFWZBP	\8.0.0\corerun.exe	?	100	?	21.27 ns	0.190 ns	0.168 ns	21.28 ns	21.04 ns	21.58 ns	1.01	Same	0.01	0.0535	-	-	224 B	1.00

ToString_MultipleSegments	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100	?	27.90 ns	0.114 ns	0.107 ns	27.89 ns	27.74 ns	28.06 ns	1.00	Base	0.00	0.0535	-	-	224 B	1.00
ToString_MultipleSegments	Job-DFWZBP	\8.0.0\corerun.exe	?	100	?	27.99 ns	0.105 ns	0.088 ns	27.98 ns	27.86 ns	28.18 ns	1.00	Same	0.00	0.0535	-	-	224 B	1.00

Append_Char	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100	?	241.87 ns	1.071 ns	1.002 ns	241.60 ns	240.66 ns	243.76 ns	1.00	Base	0.00	0.1300	-	-	544 B	1.00
Append_Char	Job-DFWZBP	\8.0.0\corerun.exe	?	100	?	241.30 ns	0.745 ns	0.661 ns	241.33 ns	240.19 ns	242.08 ns	1.00	Same	0.01	0.1293	-	-	544 B	1.00

Append_Char_Capacity	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100	?	184.25 ns	0.671 ns	0.628 ns	184.39 ns	183.50 ns	185.80 ns	1.00	Base	0.00	0.0646	-	-	272 B	1.00
Append_Char_Capacity	Job-DFWZBP	\8.0.0\corerun.exe	?	100	?	184.05 ns	0.712 ns	0.632 ns	183.91 ns	183.25 ns	185.08 ns	1.00	Same	0.00	0.0644	-	-	272 B	1.00

Append_Strings	Job-MABLYB	\8.0.0-ref\corerun.exe	1000	?	?	64,634.32 ns	412.374 ns	385.735 ns	64,675.87 ns	64,033.32 ns	65,094.01 ns	1.00	Base	0.00	99.1291	68.3914	-	559264 B	1.00
Append_Strings	Job-DFWZBP	\8.0.0\corerun.exe	1000	?	?	64,019.56 ns	593.960 ns	555.590 ns	63,872.80 ns	63,311.83 ns	65,350.13 ns	0.99	Same	0.01	99.1736	68.1818	-	559264 B	1.00

ctor_string	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100000	?	86,061.34 ns	1,523.205 ns	1,350.281 ns	86,133.38 ns	83,625.24 ns	88,818.55 ns	1.00	Base	0.00	62.1622	62.1622	62.1622	200093 B	1.00
ctor_string	Job-DFWZBP	\8.0.0\corerun.exe	?	100000	?	86,399.61 ns	1,641.253 ns	1,611.930 ns	86,427.58 ns	84,282.47 ns	88,997.28 ns	1.00	Same	0.02	62.1603	62.1603	62.1603	200093 B	1.00

ctor_capacity	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100000	?	9,895.95 ns	117.554 ns	109.960 ns	9,868.61 ns	9,753.29 ns	10,113.17 ns	1.00	Base	0.00	62.4625	62.4625	62.4625	200093 B	1.00
ctor_capacity	Job-DFWZBP	\8.0.0\corerun.exe	?	100000	?	9,870.02 ns	104.713 ns	97.948 ns	9,856.19 ns	9,737.11 ns	10,055.96 ns	1.00	Same	0.01	62.4622	62.4622	62.4622	200093 B	1.00

ToString_SingleSegment	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100000	?	82,538.59 ns	1,611.019 ns	1,654.397 ns	82,354.08 ns	80,563.27 ns	85,254.72 ns	1.00	Base	0.00	62.1811	62.1811	62.1811	200045 B	1.00
ToString_SingleSegment	Job-DFWZBP	\8.0.0\corerun.exe	?	100000	?	82,821.13 ns	1,593.155 ns	1,490.238 ns	82,308.53 ns	80,968.39 ns	85,776.82 ns	1.00	Same	0.03	62.1745	62.1745	62.1745	200045 B	1.00

ToString_MultipleSegments	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100000	?	88,075.89 ns	1,740.701 ns	1,709.601 ns	87,618.42 ns	85,793.44 ns	91,109.96 ns	1.00	Base	0.00	62.1566	62.1566	62.1566	200045 B	1.00
ToString_MultipleSegments	Job-DFWZBP	\8.0.0\corerun.exe	?	100000	?	88,520.24 ns	1,713.739 ns	1,683.121 ns	88,292.83 ns	86,143.28 ns	90,643.43 ns	1.01	Same	0.02	62.1408	62.1408	62.1408	200045 B	1.00

Append_Char	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100000	?	187,315.46 ns	827.968 ns	774.482 ns	187,259.00 ns	186,417.26 ns	189,021.21 ns	1.00	Base	0.00	49.8512	1.4881	-	209968 B	1.00
Append_Char	Job-DFWZBP	\8.0.0\corerun.exe	?	100000	?	187,439.21 ns	714.764 ns	668.591 ns	187,544.72 ns	186,596.65 ns	188,679.54 ns	1.00	Same	0.01	49.8512	1.4881	-	209968 B	1.00

Append_Char_Capacity	Job-MABLYB	\8.0.0-ref\corerun.exe	?	100000	?	252,053.05 ns	1,392.473 ns	1,302.520 ns	252,007.74 ns	250,227.38 ns	254,778.57 ns	1.00	Base	0.00	61.5079	61.5079	61.5079	200093 B	1.00
Append_Char_Capacity	Job-DFWZBP	\8.0.0\corerun.exe	?	100000	?	252,284.08 ns	880.869 ns	735.566 ns	252,625.64 ns	251,154.02 ns	253,210.07 ns	1.00	Same	0.00	61.5079	61.5079	61.5079	200093 B	1.00

Append_Object	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?		13.02 ns	0.079 ns	0.074 ns	13.02 ns	12.93 ns	13.15 ns	1.00	Base	0.00	0.0248	-	-	104 B	1.00
Append_Object	Job-DFWZBP	\8.0.0\corerun.exe	?	?		52.45 ns	0.280 ns	0.262 ns	52.46 ns	52.08 ns	53.02 ns	4.03	Slower	0.03	0.0248	-	-	104 B	1.00

Append_Object	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	Char : A	111.69 ns	0.394 ns	0.349 ns	111.61 ns	111.27 ns	112.52 ns	1.00	Base	0.00	0.1163	-	-	488 B	1.00
Append_Object	Job-DFWZBP	\8.0.0\corerun.exe	?	?	Char : A	123.70 ns	0.430 ns	0.402 ns	123.75 ns	123.14 ns	124.30 ns	1.11	Slower	0.00	0.0244	-	-	104 B	0.21

Append_Object	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	Int32 : 42	103.71 ns	0.520 ns	0.461 ns	103.49 ns	103.19 ns	104.67 ns	1.00	Base	0.00	0.0494	-	-	208 B	1.00
Append_Object	Job-DFWZBP	\8.0.0\corerun.exe	?	?	Int32 : 42	181.31 ns	0.821 ns	0.768 ns	181.44 ns	180.12 ns	182.55 ns	1.75	Slower	0.01	0.0493	-	-	208 B	1.00

Append_Object	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	Rune : A	119.31 ns	0.538 ns	0.504 ns	119.19 ns	118.73 ns	120.41 ns	1.00	Base	0.00	0.1165	-	-	488 B	1.00
Append_Object	Job-DFWZBP	\8.0.0\corerun.exe	?	?	Rune : A	117.21 ns	0.334 ns	0.279 ns	117.32 ns	116.80 ns	117.59 ns	0.98	Same	0.00	0.0247	-	-	104 B	0.21

Append_Object	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	String :	40.11 ns	0.238 ns	0.223 ns	40.06 ns	39.84 ns	40.56 ns	1.00	Base	0.00	0.0247	-	-	104 B	1.00
Append_Object	Job-DFWZBP	\8.0.0\corerun.exe	?	?	String :	95.74 ns	0.580 ns	0.543 ns	95.74 ns	95.12 ns	97.02 ns	2.39	Slower	0.02	0.0246	-	-	104 B	1.00

Append_Object	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	String : 1234567890	186.33 ns	1.191 ns	1.056 ns	185.84 ns	185.39 ns	188.99 ns	1.00	Base	0.00	0.2081	-	-	872 B	1.00
Append_Object	Job-DFWZBP	\8.0.0\corerun.exe	?	?	String : 1234567890	239.21 ns	1.255 ns	1.174 ns	239.16 ns	237.66 ns	241.99 ns	1.28	Slower	0.01	0.2078	-	-	872 B	1.00

Append_Object	Job-MABLYB	\8.0.0-ref\corerun.exe	?	?	Version : 1.2.3.4	652.52 ns	4.961 ns	4.641 ns	653.31 ns	644.76 ns	659.71 ns	1.00	Base	0.00	0.2812	-	-	1184 B	1.00
Append_Object	Job-DFWZBP	\8.0.0\corerun.exe	?	?	Version : 1.2.3.4	617.83 ns	7.158 ns	6.696 ns	619.80 ns	602.53 ns	624.03 ns	0.95	Same	0.01	0.1569	-	-	664 B	0.56

ghost · 2023-10-30T08:02:46Z

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

Issue Details

Closes #92193

Applying the optimization for ISpanFormattable, already implemented in AppendFormat, to Append.

Author:	manandre
Assignees:	-
Labels:	`area-System.Runtime`, `community-contribution`, `needs-area-label`
Milestone:	-

adamsitnik · 2023-10-30T17:13:58Z

It seems it won't be easy as dotnet/performance still does not support .NET 9.

I've created dotnet/performance#3453 to track progress on that.

stephentoub · 2023-10-31T15:34:06Z

src/libraries/System.Private.CoreLib/src/System/Text/StringBuilder.cs

            if (value.TryFormat(RemainingCurrentChunk, out int charsWritten, format: default, provider: null))
            {
+                if ((uint)charsWritten > (uint)RemainingCurrentChunkLength)


Does this measurably slow down the existing uses in overloads like Append(int)?

No noticeable impact measured.
See the new benchmark for more details

stephentoub · 2023-10-31T15:41:13Z

Append_Object | Int32 : 42 | 1.75 | Slower | 1.00 | 1.75

Taking this benchmark as an example, the benchmark data shows this increasing from something like 100ns to 180ns. Have you investigated what accounts for that difference?

manandre · 2023-11-11T19:11:10Z

New attempt with some small optimizations:

Method	data	Ratio	MannWhitney(5%)	Alloc Ratio	Total Ratio
Append_ValueTypes		1.28	Slower	0.76	0.95
Append_Object	null	2.60	Slower	1.00	2.60
Append_Object	Char : A	1.10	Slower	0.21	0.23
Append_Object	Int32 : 42	1.60	Slower	1.00	1.60
Append_Object	Rune : A	1.02	Same	0.21	0.21
Append_Object	String :	2.39	Slower	1.00	2.39
Append_Object	String : 1234567890	1.36	Slower	1.00	1.36
Append_Object	Version : 1.2.3.4	0.92	Faster	0.56	0.52

Optimizations:

Check for null first
- Huge improvement (from 4.03 to 2.60) but I still do not understand why it is not ~1.0)
Check for faulty ISpanFormattable implementation only on untrusted path
- No impact (from 1.25 to 1.28)
- It could be removed...

Benchmark summary

BenchmarkDotNet v0.13.10-nightly.20231019.90, Windows 10 (10.0.19045.3570/22H2/2022Update) Intel Core i7-4770K CPU 3.50GHz (Haswell), 1 CPU, 8 logical and 4 physical cores .NET SDK 8.0.100-rc.1.23463.5 [Host] : .NET 8.0.0 (8.0.23.41904), X64 RyuJIT AVX2 Job-TZIULB : .NET 8.0.0 (42.42.42.42424), X64 RyuJIT AVX2 Job-HAQEJN : .NET 8.0.0 (42.42.42.42424), X64 RyuJIT AVX2

PowerPlanMode=00000000-0000-0000-0000-000000000000 Arguments=/p:EnableUnsafeBinaryFormatterSerialization=true IterationTime=250.0000 ms
MaxIterationCount=20 MinIterationCount=15 WarmupCount=1

Method	Job	Toolchain	repeat	length	data	Mean	Error	StdDev	Median	Min	Max	Ratio	MannWhitney(5%)	RatioSD	Gen0	Gen1	Gen2	Allocated	Alloc Ratio
AppendLine_Strings	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	176.32 ns	1.786 ns	1.670 ns	175.90 ns	174.06 ns	179.30 ns	1.00	Base	0.00	0.3079	-	-	1288 B	1.00
AppendLine_Strings	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	175.00 ns	0.953 ns	0.845 ns	174.75 ns	173.98 ns	177.01 ns	0.99	Same	0.01	0.3078	-	-	1288 B	1.00

Append_Primitives	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	869.10 ns	8.138 ns	7.214 ns	867.57 ns	859.08 ns	887.11 ns	1.00	Base	0.00	0.2590	-	-	1096 B	1.00
Append_Primitives	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	895.44 ns	16.440 ns	14.574 ns	889.78 ns	882.77 ns	924.08 ns	1.03	Same	0.02	0.2596	-	-	1096 B	1.00

Append_ValueTypes	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	1,476.86 ns	14.795 ns	13.115 ns	1,472.30 ns	1,463.17 ns	1,504.70 ns	1.00	Base	0.00	0.7492	-	-	3152 B	1.00
Append_ValueTypes	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	1,897.06 ns	14.000 ns	12.411 ns	1,891.83 ns	1,881.45 ns	1,920.08 ns	1.28	Slower	0.01	0.5714	-	-	2408 B	0.76

Append_ValueTypes_Interpolated	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	1,788.26 ns	11.765 ns	9.824 ns	1,789.73 ns	1,777.33 ns	1,809.23 ns	1.00	Base	0.00	0.3753	-	-	1584 B	1.00
Append_ValueTypes_Interpolated	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	1,697.81 ns	7.860 ns	6.968 ns	1,696.03 ns	1,687.88 ns	1,712.35 ns	0.95	Same	0.01	0.3734	-	-	1584 B	1.00

Append_Memory	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	434.02 ns	10.320 ns	11.884 ns	431.15 ns	418.58 ns	451.38 ns	1.00	Base	0.00	0.8674	-	-	3632 B	1.00
Append_Memory	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	418.25 ns	2.382 ns	1.989 ns	418.24 ns	415.62 ns	421.44 ns	0.95	Same	0.02	0.8677	-	-	3632 B	1.00

Append_NonEmptySpan	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	377.96 ns	1.308 ns	1.160 ns	377.92 ns	376.06 ns	379.79 ns	1.00	Base	0.00	0.8673	-	-	3632 B	1.00
Append_NonEmptySpan	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	377.13 ns	3.054 ns	2.384 ns	376.36 ns	374.32 ns	381.85 ns	1.00	Same	0.01	0.8669	-	-	3632 B	1.00

Insert_Primitives	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	28,334.26 ns	179.942 ns	159.514 ns	28,357.55 ns	28,135.34 ns	28,725.80 ns	1.00	Base	0.00	2.3777	-	-	10416 B	1.00
Insert_Primitives	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	28,224.64 ns	221.316 ns	184.809 ns	28,116.62 ns	28,022.52 ns	28,524.80 ns	1.00	Same	0.01	2.4819	-	-	10416 B	1.00

Insert_Strings	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	?	487.76 ns	2.704 ns	2.529 ns	487.14 ns	483.83 ns	491.90 ns	1.00	Base	0.00	0.3162	-	-	1328 B	1.00
Insert_Strings	Job-HAQEJN	\8.0.0\corerun.exe	?	?	?	492.49 ns	9.625 ns	9.003 ns	488.76 ns	482.26 ns	509.80 ns	1.01	Same	0.02	0.3168	-	-	1328 B	1.00

Append_Strings	Job-TZIULB	\8.0.0-ref\corerun.exe	1	?	?	163.24 ns	4.070 ns	4.687 ns	163.78 ns	157.21 ns	173.39 ns	1.00	Base	0.00	0.2979	-	-	1248 B	1.00
Append_Strings	Job-HAQEJN	\8.0.0\corerun.exe	1	?	?	163.10 ns	3.538 ns	4.074 ns	164.47 ns	157.34 ns	168.85 ns	1.00	Same	0.04	0.2981	-	-	1248 B	1.00

ctor_string	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100	?	30.51 ns	0.773 ns	0.890 ns	29.98 ns	29.62 ns	32.13 ns	1.00	Base	0.00	0.0649	-	-	272 B	1.00
ctor_string	Job-HAQEJN	\8.0.0\corerun.exe	?	100	?	29.71 ns	0.123 ns	0.109 ns	29.70 ns	29.54 ns	29.88 ns	0.97	Same	0.03	0.0650	-	-	272 B	1.00

ctor_capacity	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100	?	22.74 ns	0.547 ns	0.630 ns	22.53 ns	22.07 ns	23.92 ns	1.00	Base	0.00	0.0649	-	-	272 B	1.00
ctor_capacity	Job-HAQEJN	\8.0.0\corerun.exe	?	100	?	22.58 ns	0.557 ns	0.641 ns	22.23 ns	21.94 ns	23.61 ns	0.99	Same	0.03	0.0650	-	-	272 B	1.00

ToString_SingleSegment	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100	?	21.79 ns	0.486 ns	0.541 ns	21.49 ns	21.30 ns	22.72 ns	1.00	Base	0.00	0.0535	-	-	224 B	1.00
ToString_SingleSegment	Job-HAQEJN	\8.0.0\corerun.exe	?	100	?	22.82 ns	0.062 ns	0.048 ns	22.83 ns	22.74 ns	22.88 ns	1.04	Same	0.03	0.0535	-	-	224 B	1.00

ToString_MultipleSegments	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100	?	29.06 ns	0.689 ns	0.794 ns	29.52 ns	27.87 ns	30.32 ns	1.00	Base	0.00	0.0535	-	-	224 B	1.00
ToString_MultipleSegments	Job-HAQEJN	\8.0.0\corerun.exe	?	100	?	28.07 ns	0.455 ns	0.403 ns	27.89 ns	27.70 ns	28.96 ns	0.97	Same	0.03	0.0535	-	-	224 B	1.00

Append_Char	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100	?	251.72 ns	5.350 ns	6.161 ns	252.65 ns	243.47 ns	261.01 ns	1.00	Base	0.00	0.1293	-	-	544 B	1.00
Append_Char	Job-HAQEJN	\8.0.0\corerun.exe	?	100	?	256.72 ns	2.482 ns	2.321 ns	256.01 ns	253.76 ns	260.98 ns	1.02	Same	0.03	0.1298	-	-	544 B	1.00

Append_Char_Capacity	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100	?	185.03 ns	0.835 ns	0.740 ns	184.83 ns	184.23 ns	186.83 ns	1.00	Base	0.00	0.0649	-	-	272 B	1.00
Append_Char_Capacity	Job-HAQEJN	\8.0.0\corerun.exe	?	100	?	197.20 ns	3.480 ns	3.255 ns	197.89 ns	188.80 ns	200.87 ns	1.06	Slower	0.02	0.0644	-	-	272 B	1.00

Append_Strings	Job-TZIULB	\8.0.0-ref\corerun.exe	1000	?	?	65,992.37 ns	2,104.099 ns	2,423.083 ns	64,983.75 ns	63,287.88 ns	69,519.35 ns	1.00	Base	0.00	99.1848	68.4783	-	559264 B	1.00
Append_Strings	Job-HAQEJN	\8.0.0\corerun.exe	1000	?	?	67,441.30 ns	2,219.309 ns	2,555.760 ns	68,829.80 ns	63,651.26 ns	70,694.17 ns	1.02	Same	0.03	99.0513	68.3594	-	559264 B	1.00

ctor_string	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100000	?	76,852.49 ns	1,689.878 ns	1,946.066 ns	76,834.70 ns	72,602.80 ns	79,405.60 ns	1.00	Base	0.00	62.2024	62.2024	62.2024	200093 B	1.00
ctor_string	Job-HAQEJN	\8.0.0\corerun.exe	?	100000	?	77,613.96 ns	1,387.987 ns	1,298.324 ns	77,758.55 ns	75,423.53 ns	79,770.65 ns	1.02	Same	0.03	62.1936	62.1936	62.1936	200093 B	1.00

ctor_capacity	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100000	?	9,234.93 ns	97.684 ns	86.594 ns	9,226.39 ns	9,058.55 ns	9,372.33 ns	1.00	Base	0.00	62.4658	62.4658	62.4658	200093 B	1.00
ctor_capacity	Job-HAQEJN	\8.0.0\corerun.exe	?	100000	?	9,259.14 ns	69.742 ns	65.236 ns	9,242.88 ns	9,164.18 ns	9,382.13 ns	1.00	Same	0.01	62.4652	62.4652	62.4652	200093 B	1.00

ToString_SingleSegment	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100000	?	74,861.36 ns	1,075.510 ns	1,006.033 ns	74,664.30 ns	73,128.06 ns	76,262.59 ns	1.00	Base	0.00	62.1995	62.1995	62.1995	200045 B	1.00
ToString_SingleSegment	Job-HAQEJN	\8.0.0\corerun.exe	?	100000	?	74,472.80 ns	1,001.324 ns	887.648 ns	74,564.35 ns	72,897.67 ns	75,792.43 ns	0.99	Same	0.02	62.2010	62.2010	62.2010	200045 B	1.00

ToString_MultipleSegments	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100000	?	79,509.55 ns	1,643.880 ns	1,893.094 ns	79,631.81 ns	74,305.85 ns	82,563.99 ns	1.00	Base	0.00	62.1891	62.1891	62.1891	200045 B	1.00
ToString_MultipleSegments	Job-HAQEJN	\8.0.0\corerun.exe	?	100000	?	80,059.91 ns	1,497.933 ns	1,471.170 ns	80,684.54 ns	75,999.73 ns	81,571.68 ns	1.01	Same	0.02	62.1981	62.1981	62.1981	200045 B	1.00

Append_Char	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100000	?	194,260.88 ns	4,245.082 ns	4,888.643 ns	194,229.55 ns	187,859.89 ns	202,332.52 ns	1.00	Base	0.00	49.8418	0.7911	-	209968 B	1.00
Append_Char	Job-HAQEJN	\8.0.0\corerun.exe	?	100000	?	198,968.54 ns	1,218.231 ns	1,139.534 ns	198,867.64 ns	197,097.47 ns	201,396.99 ns	1.03	Same	0.03	49.8418	0.7911	-	209968 B	1.00

Append_Char_Capacity	Job-TZIULB	\8.0.0-ref\corerun.exe	?	100000	?	247,854.18 ns	4,896.577 ns	4,809.094 ns	246,074.21 ns	242,210.52 ns	255,991.57 ns	1.00	Base	0.00	61.5079	61.5079	61.5079	200093 B	1.00
Append_Char_Capacity	Job-HAQEJN	\8.0.0\corerun.exe	?	100000	?	254,185.26 ns	2,652.187 ns	2,480.857 ns	253,832.16 ns	250,264.52 ns	257,747.58 ns	1.03	Same	0.02	61.4919	61.4919	61.4919	200093 B	1.00

Append_Object	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?		14.14 ns	0.193 ns	0.181 ns	14.13 ns	13.81 ns	14.36 ns	1.00	Base	0.00	0.0248	-	-	104 B	1.00
Append_Object	Job-HAQEJN	\8.0.0\corerun.exe	?	?		36.82 ns	0.750 ns	0.701 ns	37.09 ns	35.09 ns	37.84 ns	2.60	Slower	0.06	0.0248	-	-	104 B	1.00

Append_Object	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	Char : A	117.94 ns	1.015 ns	0.950 ns	117.97 ns	116.68 ns	119.68 ns	1.00	Base	0.00	0.1165	-	-	488 B	1.00
Append_Object	Job-HAQEJN	\8.0.0\corerun.exe	?	?	Char : A	129.13 ns	2.654 ns	2.950 ns	130.53 ns	123.53 ns	131.60 ns	1.10	Slower	0.03	0.0244	-	-	104 B	0.21

Append_Object	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	Int32 : 42	119.83 ns	2.857 ns	3.057 ns	120.92 ns	111.77 ns	123.06 ns	1.00	Base	0.00	0.0495	-	-	208 B	1.00
Append_Object	Job-HAQEJN	\8.0.0\corerun.exe	?	?	Int32 : 42	191.72 ns	3.678 ns	3.612 ns	192.06 ns	183.00 ns	197.07 ns	1.60	Slower	0.05	0.0495	-	-	208 B	1.00

Append_Object	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	Rune : A	126.17 ns	1.160 ns	1.085 ns	126.18 ns	123.81 ns	127.96 ns	1.00	Base	0.00	0.1163	-	-	488 B	1.00
Append_Object	Job-HAQEJN	\8.0.0\corerun.exe	?	?	Rune : A	128.93 ns	1.614 ns	1.510 ns	128.26 ns	127.14 ns	132.24 ns	1.02	Same	0.01	0.0247	-	-	104 B	0.21

Append_Object	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	String :	41.19 ns	1.011 ns	1.164 ns	41.03 ns	39.78 ns	43.90 ns	1.00	Base	0.00	0.0248	-	-	104 B	1.00
Append_Object	Job-HAQEJN	\8.0.0\corerun.exe	?	?	String :	98.90 ns	0.990 ns	0.827 ns	98.66 ns	97.94 ns	100.63 ns	2.39	Slower	0.07	0.0248	-	-	104 B	1.00

Append_Object	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	String : 1234567890	189.93 ns	1.681 ns	1.404 ns	189.91 ns	188.33 ns	193.26 ns	1.00	Base	0.00	0.2082	-	-	872 B	1.00
Append_Object	Job-HAQEJN	\8.0.0\corerun.exe	?	?	String : 1234567890	256.81 ns	5.046 ns	4.955 ns	258.63 ns	246.42 ns	263.39 ns	1.36	Slower	0.03	0.2084	-	-	872 B	1.00

Append_Object	Job-TZIULB	\8.0.0-ref\corerun.exe	?	?	Version : 1.2.3.4	693.07 ns	9.055 ns	8.470 ns	691.90 ns	677.27 ns	707.73 ns	1.00	Base	0.00	0.2820	-	-	1184 B	1.00
Append_Object	Job-HAQEJN	\8.0.0\corerun.exe	?	?	Version : 1.2.3.4	634.11 ns	4.454 ns	4.167 ns	633.98 ns	628.55 ns	642.33 ns	0.92	Faster	0.01	0.1587	-	-	664 B	0.56

manandre · 2023-11-11T19:43:38Z

Append_Object | Int32 : 42 | 1.75 | Slower | 1.00 | 1.75

Taking this benchmark as an example, the benchmark data shows this increasing from something like 100ns to 180ns. Have you investigated what accounts for that difference?

I have investigated this particular use case (Append_Object with an Int32 value) using the ETW profiler and Perfview.
Reference:

New:

I was expecting the impact of the cast attempt to ISpanFormattable (via the IsInstanceOfInterface method), but I do not understand why:

Reference: execution time in the tested method Append(class System.object) is 0.1% of the total !?!
New: some execution time is spent in the Append(class System.String) method whereas it should not be called at all!?!

Can someone please help me here to interpret these results?

src/libraries/System.Private.CoreLib/src/System/Text/StringBuilder.cs

stephentoub · 2024-01-22T15:58:32Z

New: some execution time is spent in the Append(class System.String) method whereas it should not be called at all!?!

Why wouldn't it be called at all? The runtime itself uses StringBuilder. Are these calls not coming from its use?

Reference: execution time in the tested method Append(class System.object) is 0.1% of the total !?!

Can you elaborate? Are you confused about it being smaller than expected or larger than expected?

manandre · 2024-02-04T21:43:11Z

I have found the explanation for the Int32: 42 case. There is a lazy-populated cache for numbers below 300, which is only used in the ToString() path and not in the TryFormat() one. It now clearly explains the surprising allocation ratio of 1.0...

runtime/src/libraries/System.Private.CoreLib/src/System/Number.Formatting.cs

Line 1954 in 7b3e409

if (value < SmallNumberCacheLength)

manandre · 2024-02-19T22:35:23Z

New benchmark execution after rebase on main branch and with .NET 9 preview 1:

Method	data	Ratio	MannWhitney(5%)	Alloc Ratio	Total Ratio
Append_ValueTypes		1.24	Slower	0.76	0.94
Append_Object	null	2.57	Slower	1.00	2.57
Append_Object	Char : A	0.79	Faster	0.21	0.17
Append_Object	Int32 : 4242	0.85	Faster	1.00	0.85
Append_Object	Rune : A	0.86	Faster	0.21	0.18
Append_Object	String :	1.24	Slower	1.00	1.24
Append_Object	String : 1234567890	1.05	Slower	1.00	1.05
Append_Object	Version : 1.2.3.4	0.87	Faster	0.56	0.49

stephentoub · 2024-07-01T14:17:11Z

I've spent some time browsing around use of Append(object), and the majority of places I see this being used wouldn't benefit from an ISpanFormattable check; the actual type often ends up being strings or other such instances. Given that there is a regression for such use, until we have better data that suggests this will be a net win, I think we should close this. Thanks for your work on it, @manandre.

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Add support for ISpanFormattable in StringBuilder.Append(Object) #92193

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Add support for ISpanFormattable in StringBuilder.Append(Object)

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Add support for ISpanFormattable in StringBuilder.Append(Object) #92197

Add support for ISpanFormattable in StringBuilder.Append(Object) #92197

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Add support for ISpanFormattable in StringBuilder.Append(Object) #92197

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