.Net 6 and 8 slower than .Net 472

[ttustonic]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I have a quite large index with 5-gram field on very large strings (tens or hundreds characters).
The program searches this index and looks for matches using NGramPhraseQuery. I usually have to look for a match for few hundred or thousand input queries.
I tested with .Net framework 4.72 , .Net 6 and .Net 8.
Results for .Net 6 and 8 are 2-4 times slower than .Net framework 4.72 for the same input.
Did you see this behaviour before, or have an idea what to look for?

Thanks, Tom

Expected Behavior

No response

Steps To Reproduce

No response

Exceptions (if any)

No response

Lucene.NET Version

4.8.0-beta00016

.NET Version

4.7.2 and 8.0.100

Operating System

Windows 10

Anything else?

No response

[jeme]

I think it would be very helpful if you tried to setup a code sample or even better something running under https://benchmarkdotnet.org/articles/guides/getting-started.html.

At the very least share relevant pieces of your code, the team will have no idea on how to begin to attempt to reproduce this as is, so more information is likely needed.

[eladmarg]

This is very strange
Can you reproduce this by test?

[ttustonic]

Thanks!
Ok, I'll try to create benchmark for this. It's not a benchmark for the different methods, but the same code under different frameworks, but, hopefully it will be OK. There might be some legal issues about sharing code and data so I'll see about creating a test program. Also, index is quite large (a few hundred megs).
Yes, I can reproduce this in my tests, running the same searches with .Net framework, 6 and 8.
I recompiled J2N and Lucene to explicitly target .Net 8, and checked whether all the feature flags are used, but it's still the same.

[jeme]

Without knowing the details, perhaps https://github.com/bchavez/Bogus can be of some assistance to create test data.

[ttustonic]

Here are benchmark results. I have also added a benchmark class. I had to rename the field names etc. but it's basically a simple search of 5-gram field.
There are two methods: SearchWithFullMatchResult and SearchWithEmptyMatchResult.
They both look for about 36000 inputs and return results.
Full method look for additional data for found hits, empty method just return a list of dummy match results.

.Net 6 full is slightly better than 472, but empty test is much slower. Also, I observed that 6 and 8 results are all over the place, sometimes the same method repeated 3 times in a row gives 2x difference in execution time. This can also be seen from the result, Stdev is quite big for .Net 6 and 8 (especially for an empty test).

This lead us to believe that there might be a problem in runtime or garbage collector, so I run the same benchmark using server GC, and now the results are great with 6 and even better with 8.

So, out immediate problem seems to be solved, but you perhaps that's something to look for.

As for test index, I can't share it publicly (and, besides, it's quite large, test case is 900MB), but perhaps there's a way to share it privately.

Thanks, Tom

Workstation GC

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.4046/22H2/2022Update)
AMD Ryzen 7 1700, 1 CPU, 16 logical and 8 physical cores
  [Host]     : .NET Framework 4.8.1 (4.8.9181.0), X64 RyuJIT VectorSize=256
  DefaultJob : .NET Framework 4.8.1 (4.8.9181.0), X64 RyuJIT VectorSize=256

Method	Mean	Error	StdDev
SearchWithFullMatchResult	47.05 s	0.235 s	0.220 s
SearchWithEmptyMatchResult	10.52 s	0.061 s	0.054 s

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.4046/22H2/2022Update)
AMD Ryzen 7 1700, 1 CPU, 16 logical and 8 physical cores
.NET SDK 8.0.200
  [Host]     : .NET 6.0.27 (6.0.2724.6912), X64 RyuJIT AVX2
  DefaultJob : .NET 6.0.27 (6.0.2724.6912), X64 RyuJIT AVX2

Method	Mean	Error	StdDev
SearchWithFullMatchResult	45.26 s	0.664 s	0.588 s
SearchWithEmptyMatchResult	34.49 s	0.686 s	1.108 s

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.4046/22H2/2022Update)
AMD Ryzen 7 1700, 1 CPU, 16 logical and 8 physical cores
.NET SDK 8.0.200
  [Host]     : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2
  DefaultJob : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2

Method	Mean	Error	StdDev
SearchWithFullMatchResult	54.08 s	0.776 s	0.648 s
SearchWithEmptyMatchResult	45.05 s	0.739 s	1.011 s

Server GC

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.4170/22H2/2022Update)
AMD Ryzen 7 1700, 1 CPU, 16 logical and 8 physical cores
  [Host]     : .NET Framework 4.8.1 (4.8.9181.0), X64 RyuJIT VectorSize=256
  DefaultJob : .NET Framework 4.8.1 (4.8.9181.0), X64 RyuJIT VectorSize=256

Method	Mean	Error	StdDev
SearchWithFullMatchResult	47.72 s	0.159 s	0.133 s
SearchWithEmptyMatchResult	11.19 s	0.159 s	0.141 s

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.4170/22H2/2022Update)
AMD Ryzen 7 1700, 1 CPU, 16 logical and 8 physical cores
.NET SDK 8.0.200
  [Host]     : .NET 6.0.28 (6.0.2824.12007), X64 RyuJIT AVX2
  DefaultJob : .NET 6.0.28 (6.0.2824.12007), X64 RyuJIT AVX2

Method	Mean	Error	StdDev
SearchWithFullMatchResult	24.183 s	0.3353 s	0.3137 s
SearchWithEmptyMatchResult	8.680 s	0.0447 s	0.0418 s

BenchmarkDotNet v0.13.12, Windows 10 (10.0.19045.4170/22H2/2022Update)
AMD Ryzen 7 1700, 1 CPU, 16 logical and 8 physical cores
.NET SDK 8.0.200
  [Host]     : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2
  DefaultJob : .NET 8.0.2 (8.0.224.6711), X64 RyuJIT AVX2

Method	Mean	Error	StdDev
SearchWithFullMatchResult	17.113 s	0.1021 s	0.0955 s
SearchWithEmptyMatchResult	6.735 s	0.0773 s	0.0723 s

[NightOwl888]

Great, this gets us a starting point. But, we will need more to narrow this down more than target framework to have any useful place to start (after all, we are maintaining over 600,000 lines of code).

One thing that would be helpful to know is whether you are benchmarking using the released components, and if not, which tag(s) or branch(es) you are compiling from source with. We have gone several hundred commits beyond the last release, so this may be relevant.

But now that you have created some benchmarks, would you consider contributing them back to us by forking the branch for #310? It is difficult for us to tell which components in the codebase are extremely common and which are extremely rare. The best we came up with was to benchmark the code in the demos, but I suspect this is still a far cry from a common real world combination of components that we should be using to determine whether a change we make is for the better or worse in terms of performance.

We still haven't seen any code, and that is the crucial bit. You don't technically need to provide an index, just the code to generate one and the code you are using to search that exhibits the behavior you are seeing. The data to generate the index can be completely based on a random seed so it generates the same data every time it is run. That way you don't have to share any real production data, and you don't have to provide a large index to us, just the code to generate the same index every time it runs.

While @jeme suggested a 3rd party package to generate test data with, do note that RandomizedTesting.Generators has several methods for generating simple or realistic strings. It is also important to base the implementation off of J2N.Randomizer instead of System.Random because .NET doesn't provide an implementation that guarantees the same random values on every target framework and operating system.

[ttustonic]

Ups, seems that I forgot to attach benchmark code and full results. I have replaced field names and removed input, but you can see what I'm measuring.
The benchmark is using Lucene.Net nuget package 4.8.0-beta00016.
As for the data, I'll be able to provide index that I used for testing and make a real test program. The data that I'm indexing are protein sequences, indexed by 5-grams. This test index is about 500 megs zipped.
Indexing code is a bit complicated, because I have providers for many different protein sources, so I'd have to extract just the code for this test data source. So, if you can accept 500 megs index, it would be easier for me, and if not, I'll make a small indexing program.
The source for the test data is
https://ftp.uniprot.org/pub/databases/uniprot/current_release/knowledgebase/complete/uniprot_sprot.fasta.gz
Thanks, Tom

BenchmarkLucene.zip
benchmarkRes.zip