[andrewlock]

Summary of changes

Removes the opt-in enforceAsyncTimeout flag (and the unused _asyncTimeout plumbing) from ApiWebRequestFactory/ApiWebRequest, its callers (AgentTransportStrategy, FeatureFlagsEvpTransport, tests), and deletes ApiWebRequestFactoryTests.AsyncDeadlineAbortsStalledJsonSendOnlyWhenEnabled.

Reason for change

#9235 added an opt-in Timer + Abort() deadline for async HttpWebRequest sends. The refactor in #9145 replaces the send path, and #9144 enforces HttpWebRequest.Timeout for every async send, so the flag no longer does anything. The deleted test asserted behaviour specific to the opt-in design: it disables HttpWebRequest.Timeout, expects a separate deadline to fire anyway, and expects a WebException(RequestCanceled).

The previous implementation had multiple issues:

• Body writer stuck on something other than the request stream would hang indefinitely
• Race condition when response returned just as the timer fires, killing a response that's already returned
• Orphaned GetResponseAsync that succeeds after the abort is not handled

Implementation details

Sits between #9145 (base) and #9144 in the stack.

Test coverage

The deadline behaviour stays covered by:

• ApiRequestTests, added in Add handling of timeouts to ApiWebRequest #9144
• FlagEvaluationTransportTests.SlowTcpAgentTimesOutWithoutReplayingBatch
• ExposureApiTimeoutTests.LegacyExposureRequestsAbortStalledConnection

On their own, #9145 and this PR have no async deadline on .NET Framework, so SlowTcpAgentTimesOutWithoutReplayingBatch fails on net48 until #9144 is applied. With the full stack applied, all transport and Feature Flags timeout tests pass locally on net48 and net10.0.

Other details

Merge together with #9144.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-22T09:43:24.993964Z	8146c97	PR opened
🔒 Security Review	🔄 Running since 2026-10-22T09:38:52.533048Z	8146c97	PR opened

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[datadog-datadog-prod-us1]

More details

The removed timeout value was already unused at the supplied base, and constructor callers are updated consistently. As documented, .NET Framework async deadline enforcement still depends on the adjacent #9144 change.

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[pr-commenter]

Benchmarks

Benchmark execution time: 2026-10-22 10:29:57

Comparing candidate commit 8146c97 in PR branch andrew/remove-async-timeout-flag with baseline commit 6aa8d46 in branch master.

📊 Benchmarking dashboard

Found 0 performance improvements and 0 performance regressions! Performance is the same for 71 metrics, 1 unstable metrics, 8 known flaky benchmarks, 118 flaky benchmarks without significant changes.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

Unstable benchmarks

These benchmarks have a confidence interval too wide to call a change; treat them as noise rather than signal.

scenario:Benchmarks.Trace.HttpClientBenchmark.SendAsync netcoreapp3.1

• unstable execution_time [+23.218ms; +48.855ms] or [+14.102%; +29.675%]

Known flaky benchmarks

These benchmarks are marked as flaky and will not trigger a failure. Modify FLAKY_BENCHMARKS_REGEX to control which benchmarks are marked as flaky.

scenario:Benchmarks.Trace.AspNetCoreBenchmark.SendRequest netcoreapp3.1

• unstable execution_time [+13.898ms; +65.584ms] or [+3.033%; +14.311%]

scenario:Benchmarks.Trace.CIVisibilityProtocolWriterBenchmark.WriteAndFlushEnrichedTraces net472

• unstable execution_time [-67.827ms; +15.932ms] or [-11.642%; +2.735%]
• unstable throughput [-51.923op/s; +14.964op/s] or [-8.746%; +2.521%]

scenario:Benchmarks.Trace.CharSliceBenchmark.OptimizedCharSliceWithPool netcoreapp3.1

• unstable throughput [-1.757op/s; +69.142op/s] or [-0.333%; +13.096%]

scenario:Benchmarks.Trace.CharSliceBenchmark.OriginalCharSlice netcoreapp3.1

• unstable throughput [+10.065op/s; +56.286op/s] or [+3.880%; +21.700%]

scenario:Benchmarks.Trace.Iast.StringAspectsBenchmark.StringConcatAspectBenchmark netcoreapp3.1

• unstable execution_time [+38.765µs; +187.671µs] or [+7.016%; +33.965%]
• unstable throughput [-291.146op/s; -25.449op/s] or [-15.923%; -1.392%]

scenario:Benchmarks.Trace.Iast.StringAspectsBenchmark.StringConcatBenchmark net472

• 🟥 allocated_mem [+8.190KB; +8.194KB] or [+16.663%; +16.671%]

scenario:Benchmarks.Trace.Iast.StringAspectsBenchmark.StringConcatBenchmark net6.0

• unstable execution_time [-4.703µs; +1.407µs] or [-8.282%; +2.478%]

scenario:Benchmarks.Trace.Iast.StringAspectsBenchmark.StringConcatBenchmark netcoreapp3.1

• unstable execution_time [-3201.596ns; +3937.596ns] or [-5.750%; +7.072%]

Known flaky benchmarks without significant changes:

• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_AddEvent_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_AddEvent_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_AddEvent_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_GetContext_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_GetContext_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_GetContext_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_SetAttributes_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_SetAttributes_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_SetAttributes_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_SetStatus_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_SetStatus_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_SetStatus_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_UpdateName_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_UpdateName_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.ActivityBenchmark.StartSpan_UpdateName_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_AddEvent_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_AddEvent_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_AddEvent_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_GetContext_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_GetContext_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_GetContext_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_RecordException_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_RecordException_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_RecordException_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_SetAttributes_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_SetAttributes_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_SetAttributes_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_SetStatus_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_SetStatus_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_SetStatus_Sampled netcoreapp3.1
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_UpdateName_Sampled net472
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_UpdateName_Sampled net6.0
• scenario:Benchmarks.OpenTelemetry.InstrumentedApi.Trace.TelemetrySpanBenchmark.StartSpan_UpdateName_Sampled netcoreapp3.1
• scenario:Benchmarks.Trace.ActivityBenchmark.StartStopWithChild net472
• scenario:Benchmarks.Trace.ActivityBenchmark.StartStopWithChild net6.0
• scenario:Benchmarks.Trace.ActivityBenchmark.StartStopWithChild netcoreapp3.1
• scenario:Benchmarks.Trace.AgentWriterBenchmark.WriteAndFlushEnrichedTraces net472
• scenario:Benchmarks.Trace.AgentWriterBenchmark.WriteAndFlushEnrichedTraces net6.0
• scenario:Benchmarks.Trace.AgentWriterBenchmark.WriteAndFlushEnrichedTraces netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleMoreComplexBody net472
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleMoreComplexBody net6.0
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleMoreComplexBody netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleSimpleBody net472
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleSimpleBody net6.0
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.AllCycleSimpleBody netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.ObjectExtractorMoreComplexBody net472
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.ObjectExtractorMoreComplexBody net6.0
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.ObjectExtractorMoreComplexBody netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.ObjectExtractorSimpleBody net472
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.ObjectExtractorSimpleBody net6.0
• scenario:Benchmarks.Trace.Asm.AppSecBodyBenchmark.ObjectExtractorSimpleBody netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeArgs net472
• scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeArgs net6.0
• scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeArgs netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeLegacyArgs net472
• scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeLegacyArgs net6.0
• scenario:Benchmarks.Trace.Asm.AppSecEncoderBenchmark.EncodeLegacyArgs netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecWafBenchmark.RunWafRealisticBenchmark net472
• scenario:Benchmarks.Trace.Asm.AppSecWafBenchmark.RunWafRealisticBenchmark net6.0
• scenario:Benchmarks.Trace.Asm.AppSecWafBenchmark.RunWafRealisticBenchmark netcoreapp3.1
• scenario:Benchmarks.Trace.Asm.AppSecWafBenchmark.RunWafRealisticBenchmarkWithAttack net472
• scenario:Benchmarks.Trace.Asm.AppSecWafBenchmark.RunWafRealisticBenchmarkWithAttack net6.0
• scenario:Benchmarks.Trace.Asm.AppSecWafBenchmark.RunWafRealisticBenchmarkWithAttack netcoreapp3.1
• scenario:Benchmarks.Trace.AspNetCoreBenchmark.SendRequest net472
• scenario:Benchmarks.Trace.AspNetCoreBenchmark.SendRequest net6.0
• scenario:Benchmarks.Trace.CIVisibilityProtocolWriterBenchmark.WriteAndFlushEnrichedTraces net6.0
• scenario:Benchmarks.Trace.CIVisibilityProtocolWriterBenchmark.WriteAndFlushEnrichedTraces netcoreapp3.1
• scenario:Benchmarks.Trace.CharSliceBenchmark.OptimizedCharSlice net472
• scenario:Benchmarks.Trace.CharSliceBenchmark.OptimizedCharSlice net6.0
• scenario:Benchmarks.Trace.CharSliceBenchmark.OptimizedCharSlice netcoreapp3.1
• scenario:Benchmarks.Trace.CharSliceBenchmark.OptimizedCharSliceWithPool net472
• scenario:Benchmarks.Trace.CharSliceBenchmark.OptimizedCharSliceWithPool net6.0
• scenario:Benchmarks.Trace.CharSliceBenchmark.OriginalCharSlice net472
• scenario:Benchmarks.Trace.CharSliceBenchmark.OriginalCharSlice net6.0
• scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearch net472
• scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearch net6.0
• scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearch netcoreapp3.1
• scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearchAsync net472
• scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearchAsync net6.0
• scenario:Benchmarks.Trace.ElasticsearchBenchmark.CallElasticsearchAsync netcoreapp3.1
• scenario:Benchmarks.Trace.GraphQLBenchmark.ExecuteAsync net472
• scenario:Benchmarks.Trace.GraphQLBenchmark.ExecuteAsync net6.0
• scenario:Benchmarks.Trace.GraphQLBenchmark.ExecuteAsync netcoreapp3.1
• scenario:Benchmarks.Trace.ILoggerBenchmark.EnrichedLog net472
• scenario:Benchmarks.Trace.ILoggerBenchmark.EnrichedLog net6.0
• scenario:Benchmarks.Trace.ILoggerBenchmark.EnrichedLog netcoreapp3.1
• scenario:Benchmarks.Trace.Iast.StringAspectsBenchmark.StringConcatAspectBenchmark net472
• scenario:Benchmarks.Trace.Iast.StringAspectsBenchmark.StringConcatAspectBenchmark net6.0
• scenario:Benchmarks.Trace.Log4netBenchmark.EnrichedLog net472
• scenario:Benchmarks.Trace.Log4netBenchmark.EnrichedLog net6.0
• scenario:Benchmarks.Trace.Log4netBenchmark.EnrichedLog netcoreapp3.1
• scenario:Benchmarks.Trace.RedisBenchmark.SendReceive net472
• scenario:Benchmarks.Trace.RedisBenchmark.SendReceive net6.0
• scenario:Benchmarks.Trace.RedisBenchmark.SendReceive netcoreapp3.1
• scenario:Benchmarks.Trace.SerilogBenchmark.EnrichedLog net472
• scenario:Benchmarks.Trace.SerilogBenchmark.EnrichedLog net6.0
• scenario:Benchmarks.Trace.SerilogBenchmark.EnrichedLog netcoreapp3.1
• scenario:Benchmarks.Trace.SingleSpanAspNetCoreBenchmark.SingleSpanAspNetCore net472
• scenario:Benchmarks.Trace.SingleSpanAspNetCoreBenchmark.SingleSpanAspNetCore net6.0
• scenario:Benchmarks.Trace.SingleSpanAspNetCoreBenchmark.SingleSpanAspNetCore netcoreapp3.1
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishScope net472
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishScope net6.0
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishScope netcoreapp3.1
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishSpan net472
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishSpan net6.0
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishSpan netcoreapp3.1
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishTwoScopes net472
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishTwoScopes net6.0
• scenario:Benchmarks.Trace.SpanBenchmark.StartFinishTwoScopes netcoreapp3.1
• scenario:Benchmarks.Trace.TraceAnnotationsBenchmark.RunOnMethodBegin net472
• scenario:Benchmarks.Trace.TraceAnnotationsBenchmark.RunOnMethodBegin net6.0
• scenario:Benchmarks.Trace.TraceAnnotationsBenchmark.RunOnMethodBegin netcoreapp3.1