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Merged
merged 5 commits into from
Jul 2, 2025
Merged

Add resiliency mechanism to CPU and memory utilization checks #6528

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d06f21b
Add RetryingLinuxUtilizationParser
amadeuszl Jun 10, 2025
c22d0ee
Switch approach to use retries in Provider class
amadeuszl Jun 20, 2025
85ab588
Merge branch 'main' into alechniak/retrying-utilization-parser
amadeuszl Jun 20, 2025
933783b
Refactor and add test
amadeuszl Jun 20, 2025
f141328
Refactor
amadeuszl Jun 20, 2025
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77 changes: 70 additions & 7 deletions ...ies/Microsoft.Extensions.Diagnostics.ResourceMonitoring/Linux/LinuxUtilizationProvider.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,10 @@
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Collections.Generic;
using System.Diagnostics.Metrics;
using System.Linq;
using System.Threading;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;
using Microsoft.Extensions.Options;
Expand Down Expand Up @@ -33,6 +36,10 @@ internal sealed class LinuxUtilizationProvider : ISnapshotProvider
private readonly double _scaleRelativeToCpuRequest;
private readonly double _scaleRelativeToCpuRequestForTrackerApi;

private readonly TimeSpan _retryInterval = TimeSpan.FromMinutes(5);
private DateTimeOffset _lastFailure = DateTimeOffset.MinValue;
private int _measurementsUnavailable;

private DateTimeOffset _refreshAfterCpu;
private DateTimeOffset _refreshAfterMemory;

Expand Down Expand Up @@ -94,18 +101,44 @@ public LinuxUtilizationProvider(IOptions<ResourceMonitoringOptions> options, ILi
// Initialize the counters
_cpuUtilizationLimit100PercentExceededCounter = meter.CreateCounter<long>("cpu_utilization_limit_100_percent_exceeded");
_cpuUtilizationLimit110PercentExceededCounter = meter.CreateCounter<long>("cpu_utilization_limit_110_percent_exceeded");
_ = meter.CreateObservableGauge(name: ResourceUtilizationInstruments.ContainerCpuLimitUtilization, observeValue: () => CpuUtilizationLimit(cpuLimit), unit: "1");
_ = meter.CreateObservableGauge(name: ResourceUtilizationInstruments.ContainerCpuRequestUtilization, observeValue: () => CpuUtilizationWithoutHostDelta() / cpuRequest, unit: "1");

_ = meter.CreateObservableGauge(
ResourceUtilizationInstruments.ContainerCpuLimitUtilization,
() => GetMeasurementWithRetry(() => CpuUtilizationLimit(cpuLimit)),
"1");

_ = meter.CreateObservableGauge(
name: ResourceUtilizationInstruments.ContainerCpuRequestUtilization,
observeValues: () => GetMeasurementWithRetry(() => CpuUtilizationWithoutHostDelta() / cpuRequest),
unit: "1");
}
else
{
_ = meter.CreateObservableGauge(name: ResourceUtilizationInstruments.ContainerCpuLimitUtilization, observeValue: () => CpuUtilization() * _scaleRelativeToCpuLimit, unit: "1");
_ = meter.CreateObservableGauge(name: ResourceUtilizationInstruments.ContainerCpuRequestUtilization, observeValue: () => CpuUtilization() * _scaleRelativeToCpuRequest, unit: "1");
_ = meter.CreateObservableGauge(name: ResourceUtilizationInstruments.ProcessCpuUtilization, observeValue: () => CpuUtilization() * _scaleRelativeToCpuRequest, unit: "1");
_ = meter.CreateObservableGauge(
name: ResourceUtilizationInstruments.ContainerCpuLimitUtilization,
observeValues: () => GetMeasurementWithRetry(() => CpuUtilization() * _scaleRelativeToCpuLimit),
unit: "1");

_ = meter.CreateObservableGauge(
name: ResourceUtilizationInstruments.ContainerCpuRequestUtilization,
observeValues: () => GetMeasurementWithRetry(() => CpuUtilization() * _scaleRelativeToCpuRequest),
unit: "1");

_ = meter.CreateObservableGauge(
name: ResourceUtilizationInstruments.ProcessCpuUtilization,
observeValues: () => GetMeasurementWithRetry(() => CpuUtilization() * _scaleRelativeToCpuRequest),
unit: "1");
}

_ = meter.CreateObservableGauge(name: ResourceUtilizationInstruments.ContainerMemoryLimitUtilization, observeValue: MemoryUtilization, unit: "1");
_ = meter.CreateObservableGauge(name: ResourceUtilizationInstruments.ProcessMemoryUtilization, observeValue: MemoryUtilization, unit: "1");
_ = meter.CreateObservableGauge(
name: ResourceUtilizationInstruments.ContainerMemoryLimitUtilization,
observeValues: () => GetMeasurementWithRetry(() => MemoryUtilization()),
unit: "1");

_ = meter.CreateObservableGauge(
name: ResourceUtilizationInstruments.ProcessMemoryUtilization,
observeValues: () => GetMeasurementWithRetry(() => MemoryUtilization()),
unit: "1");

// cpuRequest is a CPU request (aka guaranteed number of CPU units) for pod, for host its 1 core
// cpuLimit is a CPU limit (aka max CPU units available) for a pod or for a host.
Expand Down Expand Up @@ -288,4 +321,34 @@ public Snapshot GetSnapshot()
userTimeSinceStart: TimeSpan.FromTicks((long)(cgroupTime / Hundred * _scaleRelativeToCpuRequestForTrackerApi)),
memoryUsageInBytes: memoryUsed);
}

private IEnumerable<Measurement<double>> GetMeasurementWithRetry(Func<double> func)
{
if (Volatile.Read(ref _measurementsUnavailable) == 1 &&
_timeProvider.GetUtcNow() - _lastFailure < _retryInterval)
{
return Enumerable.Empty<Measurement<double>>();
}

try
{
double result = func();
if (Volatile.Read(ref _measurementsUnavailable) == 1)
{
_ = Interlocked.Exchange(ref _measurementsUnavailable, 0);
}

return new[] { new Measurement<double>(result) };
}
catch (Exception ex) when (
ex is System.IO.FileNotFoundException ||
ex is System.IO.DirectoryNotFoundException ||
ex is System.UnauthorizedAccessException)
{
_lastFailure = _timeProvider.GetUtcNow();
_ = Interlocked.Exchange(ref _measurementsUnavailable, 1);

return Enumerable.Empty<Measurement<double>>();
}
}
}
130 changes: 130 additions & 0 deletions ...ft.Extensions.Diagnostics.ResourceMonitoring.Tests/Linux/LinuxUtilizationProviderTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
using System.Threading.Tasks;
using Microsoft.Extensions.Diagnostics.ResourceMonitoring.Test.Helpers;
using Microsoft.Extensions.Logging.Testing;
using Microsoft.Extensions.Time.Testing;
using Microsoft.Shared.Instruments;
using Microsoft.TestUtilities;
using Moq;
Expand Down Expand Up @@ -272,4 +273,133 @@ public void Provider_Registers_Instruments_CgroupV2_WithoutHostCpu()
Assert.Contains(samples, x => x.instrument.Name == ResourceUtilizationInstruments.ProcessMemoryUtilization);
Assert.Equal(1, samples.Single(i => i.instrument.Name == ResourceUtilizationInstruments.ProcessMemoryUtilization).value);
}

[Fact]
public void Provider_GetMeasurementWithRetry_HandlesExceptionAndRecovers()
{
var meterName = Guid.NewGuid().ToString();
var logger = new FakeLogger<LinuxUtilizationProvider>();
var options = Options.Options.Create(new ResourceMonitoringOptions());
using var meter = new Meter(nameof(Provider_GetMeasurementWithRetry_HandlesExceptionAndRecovers));
var meterFactoryMock = new Mock<IMeterFactory>();
meterFactoryMock.Setup(x => x.Create(It.IsAny<MeterOptions>()))
.Returns(meter);

var callCount = 0;
var parserMock = new Mock<ILinuxUtilizationParser>();
parserMock.Setup(p => p.GetMemoryUsageInBytes()).Returns(() =>
{
callCount++;
if (callCount <= 1)
{
throw new FileNotFoundException("Simulated failure to read file");
}

return 420UL;
});
parserMock.Setup(p => p.GetAvailableMemoryInBytes()).Returns(1000UL);
parserMock.Setup(p => p.GetCgroupRequestCpu()).Returns(10f);
parserMock.Setup(p => p.GetCgroupLimitedCpus()).Returns(12f);

var fakeTime = new FakeTimeProvider(DateTimeOffset.UtcNow);
var provider = new LinuxUtilizationProvider(options, parserMock.Object, meterFactoryMock.Object, logger, fakeTime);

using var listener = new MeterListener
{
InstrumentPublished = (instrument, listener) =>
{
if (ReferenceEquals(meter, instrument.Meter))
{
listener.EnableMeasurementEvents(instrument);
}
}
};

var samples = new List<(Instrument instrument, double value)>();
listener.SetMeasurementEventCallback<double>((instrument, value, _, _) =>
{
if (ReferenceEquals(meter, instrument.Meter))
{
samples.Add((instrument, value));
}
});

listener.Start();
listener.RecordObservableInstruments();
Assert.DoesNotContain(samples, x => x.instrument.Name == ResourceUtilizationInstruments.ProcessMemoryUtilization);

fakeTime.Advance(TimeSpan.FromMinutes(1));
listener.RecordObservableInstruments();
Assert.DoesNotContain(samples, x => x.instrument.Name == ResourceUtilizationInstruments.ProcessMemoryUtilization);

fakeTime.Advance(TimeSpan.FromMinutes(5));
listener.RecordObservableInstruments();
var metric = samples.SingleOrDefault(x => x.instrument.Name == ResourceUtilizationInstruments.ProcessMemoryUtilization);
Assert.Equal(0.42, metric.value);

parserMock.Verify(p => p.GetMemoryUsageInBytes(), Times.Exactly(2));
}

[Fact]
public void Provider_GetMeasurementWithRetry_UnhandledException_DoesNotBlockFutureReads()
{
var meterName = Guid.NewGuid().ToString();
var logger = new FakeLogger<LinuxUtilizationProvider>();
var options = Options.Options.Create(new ResourceMonitoringOptions());
using var meter = new Meter(nameof(Provider_GetMeasurementWithRetry_UnhandledException_DoesNotBlockFutureReads));
var meterFactoryMock = new Mock<IMeterFactory>();
meterFactoryMock.Setup(x => x.Create(It.IsAny<MeterOptions>()))
.Returns(meter);

var callCount = 0;
var parserMock = new Mock<ILinuxUtilizationParser>();
parserMock.Setup(p => p.GetMemoryUsageInBytes()).Returns(() =>
{
callCount++;
if (callCount <= 2)
{
throw new InvalidOperationException("Simulated unhandled exception");
}

return 1234UL;
});
parserMock.Setup(p => p.GetAvailableMemoryInBytes()).Returns(2000UL);
parserMock.Setup(p => p.GetCgroupRequestCpu()).Returns(10f);
parserMock.Setup(p => p.GetCgroupLimitedCpus()).Returns(12f);

var fakeTime = new FakeTimeProvider(DateTimeOffset.UtcNow);
var provider = new LinuxUtilizationProvider(options, parserMock.Object, meterFactoryMock.Object, logger, fakeTime);

using var listener = new MeterListener
{
InstrumentPublished = (instrument, listener) =>
{
if (ReferenceEquals(meter, instrument.Meter))
{
listener.EnableMeasurementEvents(instrument);
}
}
};

var samples = new List<(Instrument instrument, double value)>();
listener.SetMeasurementEventCallback<double>((instrument, value, _, _) =>
{
if (ReferenceEquals(meter, instrument.Meter))
{
samples.Add((instrument, value));
}
});

listener.Start();

Assert.Throws<AggregateException>(() => listener.RecordObservableInstruments());
Assert.DoesNotContain(samples, x => x.instrument.Name == ResourceUtilizationInstruments.ProcessMemoryUtilization);

fakeTime.Advance(TimeSpan.FromMinutes(1));
listener.RecordObservableInstruments();
var metric = samples.SingleOrDefault(x => x.instrument.Name == ResourceUtilizationInstruments.ProcessMemoryUtilization);
Assert.Equal(1234f / 2000f, metric.value, 0.01f);

parserMock.Verify(p => p.GetMemoryUsageInBytes(), Times.Exactly(3));
}
}
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