perf: Speed up SDK init

[jairbubbles]

In some scenarios the time spent in initializing the SDK can be too important. What is tricky is that the init of the SDK is one of the first thing the app do and we're JITing almost everything. Creating a HttpClient, a Regex is costly...

In this pull request I'm experimenting with lazy instanciation so all that JIT time for these types will be spent afterwards.

I'm disabling almost everything to be in the best scenario possible:

await Task.Run(() =>
{
    SentrySdk.Init(o =>
    {
        o.Dsn = "<sentry_dsn>";
        o.Release = "1.0.0";
        o.DisableAppDomainProcessExitFlush();
        o.DisableAppDomainUnhandledExceptionCapture();
        o.DisableUnobservedTaskExceptionCapture();
        o.DisableDuplicateEventDetection();
        o.DisableDiagnosticSourceIntegration();
        o.DisableWinUiUnhandledExceptionIntegration(); // this one is new!
        o.AutoSessionTracking = false;
        o.IsGlobalModeEnabled = true;
        o.DetectStartupTime = StartupTimeDetectionMode.Fast;
        o.TracesSampleRate = 0;
    });
});

Here is the current status:

Compared to main branch:

Let me know what you think!

[bruno-garcia]

Nice! Thanks for this PR, the idea makes sense. I realize it's a draft but left some notes already.

Could you please add some benchmarks in https://github.com/getsentry/sentry-dotnet/tree/main/benchmarks ?

[jairbubbles]

Could you please add some benchmarks in https://github.com/getsentry/sentry-dotnet/tree/main/benchmarks ?

I struggled a bit to add the benchmarks as I needed a specific "ColdStart" configuration but here we go:

Method	Mean	Error	StdDev	Min	Max	Median	Methods JITted	Methods Tiered	JIT allocated memory	Allocated
'Init SDK (Full)'	47.02 ms	2.512 ms	1.661 ms	45.32 ms	50.16 ms	46.63 ms	1,051	1	192 KB	43.83 KB
'Init SDK (Slim)'	28.04 ms	2.237 ms	1.479 ms	27.01 ms	32.18 ms	27.61 ms	900	1	165 KB	39.87 KB

But it's not so convincing when running it on main to compare:

Method	Mean	Error	StdDev	Min	Max	Median	Methods JITted	Methods Tiered	JIT allocated memory	Allocated
'Init SDK (Full)'	53.49 ms	4.709 ms	3.115 ms	51.52 ms	61.17 ms	52.12 ms	1,060	1	191 KB	49.09 KB
'Init SDK (Slim)'	44.01 ms	3.667 ms	2.426 ms	41.61 ms	50.16 ms	43.20 ms	962	1	175 KB	33.35 KB

[jairbubbles]

Some notes:

• Dns.Parse is still taking a bit of time (20ms), maybe we could do a simple verification in the constructor and lazy init it?
• Some features which I disabled in my use case were taking a lot of time : in particular AutoSession is writing / reading a file for the persistant id.

[vaind]

Dns.Parse is still taking a bit of time (20ms),

that's not a bit of time, that's a lot of time for such a simple operation (seemingly). Could use a bit more investigation.

[jairbubbles]

Dns.Parse is still taking a bit of time (20ms),

that's not a bit of time, that's a lot of time for such a simple operation (seemingly). Could use a bit more investigation.

Yeah but it's due to JIT.

[bruno-garcia]

Dns.Parse is still taking a bit of time (20ms),

that's not a bit of time, that's a lot of time for such a simple operation (seemingly). Could use a bit more investigation.

Yeah but it's due to JIT.

We looked at it with @bitsandfoxes when profiling this and IIRC it was mainly the Uri class, most time spent.
If that's the case we could prob stop using it and take a simpler approach.
We parse it in other SDKs, e.g in C: https://github.com/getsentry/sentry-native/blob/406d41881111d15b1144b443d51760c1415c8029/src/sentry_utils.c#L216-L270

[bruno-garcia]

This is quite promising.Once it's out of draft we can test it against feat/4.0.0 to make sure it works fine with AOT

[bruno-garcia]

But it's not so convincing when running it on main to compare:

Would be more noticible if we had some "application code" right after Init. That now would get a chance to run before some gets sent into Sentry vs before where it would need everything to bootstrap

[jairbubbles]

With latest changes, here are the benchmarks results:

Method	Mean	Error	StdDev	Min	Max	Median	Methods JITted	Methods Tiered	JIT allocated memory	Allocated
'Init SDK (Full)'	42.91 ms	1.679 ms	1.110 ms	41.51 ms	44.63 ms	42.52 ms	1,028	1	186 KB	43.05 KB
'Init SDK (Slim)'	25.45 ms	0.981 ms	0.649 ms	24.51 ms	26.25 ms	25.56 ms	891	1	161 KB	27.22 KB

[bruno-garcia]

Great stuff! Thanks @jairbubbles
Prob needs @bitsandfoxes @vaind or @jamescrosswell as some extra check before we can merge but lgtm

[bitsandfoxes]

Those are some serious gains! I'll follow up with a review/merge this tomorrow.

[bitsandfoxes]

Let me run this against 4.0.0 before merging to avoid any heartache.

[bruno-garcia]

Lets merge this and figure out AOT after

[bruno-garcia]

Thanks @jairbubbles

[bitsandfoxes]

Already tested. Works like a charm. No hickups there!