feat: blocking detection #2709
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,12 @@ | ||
| Sample usages of the Sentry SDK for ASP.NET Core on an MVC app | ||
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| Start by changing the DSN in `appsettings.json`, `Sentry:Dsn` property with your own. | ||
| No DSN yet? Get one for free at https://sentry.io/ to give this sample a run. | ||
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| Blocking detection: | ||
| * It's turned on via option `CaptureBlockingCalls` | ||
| * In the `HomeController` there's an action that causes a blocking call on an async method. | ||
| * You can trigger it with: | ||
| * `GET http://localhost:5001/home/block/true` | ||
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| Results `Was blocking? True` and an event captured in Sentry. |
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| Original file line number | Diff line number | Diff line change |
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@@ -11,55 +11,4 @@ | |
| <ProjectReference Include="..\..\src\Sentry.AspNetCore\Sentry.AspNetCore.csproj" /> | ||
| </ItemGroup> | ||
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| </Project> | ||
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,107 @@ | ||
| using Sentry.Internal; | ||
| using Sentry.Protocol; | ||
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| // Namespace starting with Sentry makes sure the SDK cuts frames off before reporting | ||
| namespace Sentry.Ben.BlockingDetector | ||
| { | ||
| internal class BlockingMonitor : IBlockingMonitor | ||
| { | ||
| private readonly Func<IHub> _getHub; | ||
| private readonly SentryOptions _options; | ||
| internal readonly IRecursionTracker _recursionTracker; | ||
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| public BlockingMonitor(Func<IHub> getHub, SentryOptions options) | ||
| : this(getHub, options, new StaticRecursionTracker()) | ||
| { | ||
| } | ||
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| internal BlockingMonitor(Func<IHub> getHub, SentryOptions options, IRecursionTracker recursionTracker) | ||
| { | ||
| _getHub = getHub; | ||
| _options = options; | ||
| _recursionTracker = recursionTracker; | ||
| } | ||
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| private static bool ShouldSkipFrame(string? frameInfo) => | ||
| frameInfo?.StartsWith("Sentry.Ben") == true | ||
| // Skip frames relating to the TaskBlockingListener | ||
| || frameInfo?.StartsWith("System.Diagnostics") == true | ||
| // Skip frames relating to the async state machine | ||
| || frameInfo?.StartsWith("System.Threading") == true; | ||
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There was a problem hiding this comment. I think we can skip doing this and improve grouping on the server side for this kind of stuff in general. There was a problem hiding this comment. @bitsandfoxes could you link to the associated PR where this logic gets changed on the server? Also, if we do skip this here, we'll need to make some changes to set a custom fingerprint that excludes all this stuff (since by default the entire stacktrace is used as the fingerprint). There was a problem hiding this comment. I'll follow up on this. The blocking detection is opt-in and the improvements to the grouping are not blocking this PR. #3202 There was a problem hiding this comment.
If we remove the logic above from the client, the grouping will be broken unless some similar logic exists on the server. I had a chat to Bruno though... Not sure we need to be doing this on the server. |
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| public void BlockingStart(DetectionSource detectionSource) | ||
| { | ||
| // From Stephen Cleary: | ||
| // "The default SynchronizationContext queues its asynchronous delegates to the ThreadPool but executes its | ||
| // synchronous delegates directly on the calling thread." | ||
| // | ||
| // Implicitly then, if we're not on a ThreadPool thread, we're not in an async context. | ||
| if (!Thread.CurrentThread.IsThreadPoolThread) | ||
| { | ||
| return; | ||
| } | ||
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| _recursionTracker.Recurse(); | ||
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| try | ||
| { | ||
| if (!_recursionTracker.IsFirstRecursion()) | ||
| { | ||
| return; | ||
| } | ||
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| var stackTrace = DebugStackTrace.Create( | ||
| _options, | ||
| new StackTrace(true), | ||
| true, | ||
| ShouldSkipFrame | ||
| ); | ||
| var evt = new SentryEvent | ||
| { | ||
| Level = SentryLevel.Warning, | ||
| Message = | ||
| "Blocking method has been invoked and blocked, this can lead to ThreadPool starvation. Learn more about it: " + | ||
| "https://learn.microsoft.com/en-us/aspnet/core/fundamentals/best-practices#avoid-blocking-calls ", | ||
| SentryExceptions = new[] | ||
| { | ||
| new SentryException | ||
| { | ||
| ThreadId = Environment.CurrentManagedThreadId, | ||
| Mechanism = new Mechanism | ||
| { | ||
| Type = "BlockingCallDetector", | ||
| Handled = false, | ||
| Description = "Blocking calls can cause ThreadPool starvation.", | ||
| Source = detectionSource.ToString() | ||
| }, | ||
| Type = "Blocking call detected", | ||
| Stacktrace = stackTrace, | ||
| } | ||
| }, | ||
| }; | ||
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| _getHub().CaptureEvent(evt); | ||
| } | ||
| catch | ||
| { | ||
| // ignored | ||
| } | ||
| } | ||
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| public void BlockingEnd() | ||
| { | ||
| if (!Thread.CurrentThread.IsThreadPoolThread) | ||
| { | ||
| return; | ||
| } | ||
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| _recursionTracker.Backtrack(); | ||
| } | ||
| } | ||
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| internal enum DetectionSource | ||
| { | ||
| SynchronizationContext, | ||
| EventListener | ||
| } | ||
| } | ||
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@bruno-garcia won't the SynchronizationContext in ASP.NET Core always be null? Is this code here just in case SDK users have implemented a custom sync context for some reason?