improvement regex

[EngRajabi]

improvement regex with compile flag

[JRahnama]

@EngRajabi I am not sure if that makes any good here.

Compiled regular expressions maximize run-time performance at the expense of initialization time.

Can you provide some bench marking to support your idea please?

[EngRajabi]

Yes, I did.It is a bit slow to use the first time, but much faster the next time
https://medium.com/@mohsen_rajabi/how-to-write-a-regex-very-fast-in-c-best-practice-875d386c0485

[JRahnama]

Yes, I did.It is a bit slow to use the first time, but much faster the next time

@DavoudEshtehari and @Wraith2 any opinion on this? I think we should not sacrifice initialization time for runtime performance unless we have a good benchmark to show a practical test case.

@EngRajabi can you write a test case with SqlClient and do some benchmarking on it? The one you have provided is merely for RegEx and does not contain any SqlClient related tests.

[Wraith2]

@DavoudEshtehari and @Wraith2 any opinion on this? I think we should not sacrifice initialization time for runtime performance unless we have a good benchmark to show a practical test case.

I looked at this when it was posted and my opinon was that it is not harmful. It's not in a heavily used code path for any performance benchmarks I've seen so it's not going to cause trouble for most people. If it is heavily used for a small number of people then this is probably an improvement for them. Ideally I'd like to see benchmark numbers but it's a single line change in a low traffic area that might benefit users so I'm not against it.

We keep a reference the to the regex so we're not relying on the static regex cache we will do the work only once. On netfx compiled regex output an assembly which is going to cause codegen which is slow but if it's heavily used there may be an overall perf benefit. On netcore <7 compiled flag does nothing, on 7+ it may cause a build time code generator to generate the compiled expression which will be faster for users in all cases.

[DavoudEshtehari]

Following the Wraith2 comment, it'll improve a small number of customers with high loads.

• Regular Expression Performance
  
  

Best Practices
To maximize the performance of regular expressions in the .NET Framework, we recommend that you do the following when working with regular expression objects:

• Call static regular expression matching methods instead of repeatedly instantiating the same regular expression object.
• Use interpreted regular expressions when you expect to call pattern-matching methods a limited number of times to parse text.
• Use compiled regular expressions to optimize performance for regular expression patterns that are known in advance and when the frequency of calls to the regular expression’s pattern-matching methods can vary extensively.

[EngRajabi]

Thanks for the explanation friends
According to Microsoft documentation
https://docs.microsoft.com/en-us/dotnet/standard/base-types/best-practices

And the test I took
https://medium.com/@mohsen_rajabi/how-to-write-a-regex-very-fast-in-c-best-practice-875d386c0485

The following should be noted in regular expressions
-Use the Regex object statically because they are threadsafe
-Use the compiled flag