Azure Application Insights 采样更改了采样率

Question

我们的一个 azure Function v3 应用从 200mb 的应用洞察摄取量减少到约 18gb。我们没有添加任何额外的日志记录语句、更改任何 sdk 或触发任何额外的函数执行。我们没有在我们的项目中指定 app insights sdk，因此它使用 Azure 已安装的内容。运行下面 Microsoft 推荐的显示采样百分比的查询使得自适应采样发生了明显的变化。

union requests,dependencies,pageViews,browserTimings,exceptions,traces
| where timestamp > ago(50d)
| summarize RetainedPercentage = 100/avg(itemCount) by bin(timestamp, 1h), itemType
|  order by timestamp, itemType

这是在出现峰值之前

这是在出现峰值之后

这是host.json

{
  "version": "2.0",
  "logging": {
    "logLevel": {
      "default": "Information",
      "Host.Triggers.DurableTask": "Warning",
      "DurableTask.AzureStorage": "Warning",
      "DurableTask.Core": "Warning"
    },
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "extensions": {
    "eventHubs": {
      "batchCheckpointFrequency": 1,
      "eventProcessorOptions": {
        "maxBatchSize": 64,
        "prefetchCount": 128
      }
    },
    "durableTask": {
      "hubName": "FooDevicesTaskHub",
      "storageProvider": {
        "connectionStringName": "AzureWebJobsStorageDurable"
      },
      "tracing": {
        "traceInputsAndOutputs": false,
        "traceReplayEvents": false
      }
    },
    "serviceBus": {
      "messageHandlerOptions": {
        "maxConcurrentCalls": 1
      }
    }
  }
}

这是包裹

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AzureFunctionsVersion>v3</AzureFunctionsVersion>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="AutoMapper" Version="8.1.1" />
    <PackageReference Include="Azure.Storage.Blobs" Version="12.8.0" />
    <PackageReference Include="Azure.Storage.Files.DataLake" Version="12.2.2" />
    <PackageReference Include="Microsoft.Azure.Devices" Version="1.18.1" />
    <PackageReference Include="Microsoft.Azure.EventGrid" Version="3.2.0" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.CosmosDB" Version="3.0.7" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.DurableTask" Version="2.5.1" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.EventGrid" Version="2.1.0" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.EventHubs" Version="4.1.1" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.ServiceBus" Version="4.3.0" />
    <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.Storage" Version="4.0.3" />
    <PackageReference Include="Microsoft.Extensions.Http" Version="3.1.7" />
    <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="3.0.13" />
    <PackageReference Include="Microsoft.Azure.Functions.Extensions" Version="1.0.0" />
    <PackageReference Include="Polly" Version="7.2.1" />
    <PackageReference Include="Polly.Contrib.WaitAndRetry" Version="1.1.1" />
    <PackageReference Include="SendGrid" Version="9.24.2" />
    <PackageReference Include="System.Net.Http.Json" Version="5.0.0" />
  </ItemGroup>

添加了更多基于评论的查询结果：

traces
| summarize sum(itemCount), count(), dcount(strcat(cloud_RoleName, "/")) by bin(timestamp, 30sec)
| render timechart

之前：

之后：

关于什么可能导致此问题或需要寻找什么的任何想法？我们有一张 MS 的票，但他们已经调查了几周。

Answer 1

自适应采样基于每个应用实例。因此，如果每个节点的负载减少（整体负载减少或者您重构了您的应用程序{切换到其他计划等}并且现在有更小的实例等）那么这可以解释这些数字。

要检查是否是这种情况，您可以输出以下列：

sum(itemCount), count(), dcount(strcat(cloud_RoleName, "/", cloud_RoleInstance), 4)

Azure Application Insights 采样更改了采样率

Azure Application Insights sampling changed sampling rate

azure-functions

appinsights