Enable backpressure handling by default (#4615)

Author: jamescrosswell

CHANGELOG.md

@@ -7,6 +7,7 @@
 - `BreadcrumbLevel.Critical` has been renamed to `BreadcrumbLevel.Fatal` for consistency with the other Sentry SDKs ([#4605](https://github.com/getsentry/sentry-dotnet/pull/4605))
 - SentryOptions.IsEnvironmentUser now defaults to false on MAUI. The means the User.Name will no longer be set, by default, to the name of the device ([#4606](https://github.com/getsentry/sentry-dotnet/pull/4606))
 - Remove unnecessary files from SentryCocoaFramework before packing ([#4602](https://github.com/getsentry/sentry-dotnet/pull/4602))
+- Backpressure handling is now enabled by default, meaning that the SDK will monitor system health and reduce the sampling rate of events and transactions when the system is under load. When the system is determined to be healthy again, the sampling rates are returned to their original levels. ([#4615](https://github.com/getsentry/sentry-dotnet/pull/4615))
 - ScopeExtensions.Populate is now internal ([#4611](https://github.com/getsentry/sentry-dotnet/pull/4611))
 
 ### Fixes

src/Sentry/SentryOptions.cs

@@ -98,7 +98,10 @@ public bool IsGlobalModeEnabled
     /// Enables or disables automatic backpressure handling. When enabled, the SDK will monitor system health and
     /// reduce the sampling rate of events and transactions when the system is under load.
     /// </summary>
-    public bool EnableBackpressureHandling { get; set; } = false;
+    /// <remarks>
+    /// Defaults to true / enabled.
+    /// </remarks>
+    public bool EnableBackpressureHandling { get; set; } = true;
 
     /// <summary>
     /// This holds a reference to the current transport, when one is active.

test/Sentry.Tests/SentryOptionsTests.Integrations_default_ones_are_properly_registered.DotNet10_0.DotNet.verified.txt

@@ -5,6 +5,9 @@
       https://d4d82fc1c2c4032a83f3a29aa3a3aff@fake-sentry.io:65535/2147483647
     ]
   },
+  {
+    Message: Starting BackpressureMonitor.
+  },
   {
     Message: Registering integration: '{0}'.,
     Args: [

test/Sentry.Tests/SentryOptionsTests.Integrations_default_ones_are_properly_registered.DotNet10_0.Windows.DotNet.verified.txt

@@ -5,6 +5,9 @@
       https://d4d82fc1c2c4032a83f3a29aa3a3aff@fake-sentry.io:65535/2147483647
     ]
   },
+  {
+    Message: Starting BackpressureMonitor.
+  },
   {
     Message: Registering integration: '{0}'.,
     Args: [

test/Sentry.Tests/SentryOptionsTests.Integrations_default_ones_are_properly_registered.DotNet8_0.DotNet.verified.txt

@@ -5,6 +5,9 @@
       https://d4d82fc1c2c4032a83f3a29aa3a3aff@fake-sentry.io:65535/2147483647
     ]
   },
+  {
+    Message: Starting BackpressureMonitor.
+  },
   {
     Message: Registering integration: '{0}'.,
     Args: [

test/Sentry.Tests/SentryOptionsTests.Integrations_default_ones_are_properly_registered.DotNet8_0.Windows.DotNet.verified.txt

@@ -5,6 +5,9 @@
       https://d4d82fc1c2c4032a83f3a29aa3a3aff@fake-sentry.io:65535/2147483647
     ]
   },
+  {
+    Message: Starting BackpressureMonitor.
+  },
   {
     Message: Registering integration: '{0}'.,
     Args: [

test/Sentry.Tests/SentryOptionsTests.Integrations_default_ones_are_properly_registered.DotNet9_0.DotNet.verified.txt

@@ -5,6 +5,9 @@
       https://d4d82fc1c2c4032a83f3a29aa3a3aff@fake-sentry.io:65535/2147483647
     ]
   },
+  {
+    Message: Starting BackpressureMonitor.
+  },
   {
     Message: Registering integration: '{0}'.,
     Args: [

test/Sentry.Tests/SentryOptionsTests.Integrations_default_ones_are_properly_registered.DotNet9_0.Windows.DotNet.verified.txt

@@ -5,6 +5,9 @@
       https://d4d82fc1c2c4032a83f3a29aa3a3aff@fake-sentry.io:65535/2147483647
     ]
   },
+  {
+    Message: Starting BackpressureMonitor.
+  },
   {
     Message: Registering integration: '{0}'.,
     Args: [

test/Sentry.Tests/SentryOptionsTests.Integrations_default_ones_are_properly_registered.Net4_8.Windows.Net.verified.txt

@@ -5,6 +5,9 @@
       https://d4d82fc1c2c4032a83f3a29aa3a3aff@fake-sentry.io:65535/2147483647
     ]
   },
+  {
+    Message: Starting BackpressureMonitor.
+  },
   {
     Message: Registering integration: '{0}'.,
     Args: [

test/Sentry.Tests/SentryOptionsTests.cs

@@ -13,6 +13,13 @@ public void DecompressionMethods_ByDefault_AllBitsSet()
         Assert.Equal(~DecompressionMethods.None, sut.DecompressionMethods);
     }
 
+    [Fact]
+    public void EnableBackpressureHandling_Default_True()
+    {
+        var sut = new SentryOptions();
+        sut.EnableBackpressureHandling.Should().BeTrue();
+    }
+
     [Fact]
     public void RequestBodyCompressionLevel_ByDefault_Optimal()
     {