Use the new .NET 8 APIs to configure max heap memory size #1578
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…process to match the max memory configured for the Lambda function.
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PR on .NET runtime repository to remove the preview attributes for the new API: dotnet/runtime#91622 |
philasmar
reviewed
Sep 13, 2023
| try | ||
| { | ||
| int lambdaMemoryInMb; | ||
| if (!int.TryParse(Environment.GetEnvironmentVariable("AWS_LAMBDA_FUNCTION_MEMORY_SIZE"), out lambdaMemoryInMb)) |
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nit: add the environment variable as a constant
| if (!int.TryParse(Environment.GetEnvironmentVariable("AWS_LAMBDA_FUNCTION_MEMORY_SIZE"), out lambdaMemoryInMb)) | ||
| return; | ||
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| ulong memoryInBytes = (ulong)lambdaMemoryInMb * 1048576; |
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nit: break 1,048,576 down into 1024 x 1024 just for readability
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| // The RefreshMemoryLimit API is currently marked as a preview feature. Disable the warning for now but this | ||
| // feature can not be merged till the API is no longer marked as preview. | ||
| #pragma warning disable CA2252 | ||
| GC.RefreshMemoryLimit(); | ||
| #pragma warning disable CA2252 |
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The PR dotnet/runtime#91622 was merged. Could you please remove the part around disabling the warning?
philasmar
approved these changes
Sep 25, 2023
96malhar
approved these changes
Sep 25, 2023
philasmar
approved these changes
Oct 12, 2023
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The .NET runtime does recognize the memory limits that have been set by Lambda's cgroup configuration. As part of .NET 8 the .NET team added support for configuring the max heap memory size via the
AppContext.SetData("GCHeapHardLimit", memoryInBytes);andGC.RefreshMemoryLimit();APIs. Refer to this GitHub issue for more information on these APIs. dotnet/runtime#70601The Lambda runtime client (Amazon.Lambda.RuntimeSupport) is now using these APIs for functions that target .NET 8 by taking the memory size configured for the Lambda function and communicating that size to the .NET runtime via the new APIs. This is done via the new
AdjustMemorySettingsmethod inLambdaBootstrapinside RuntimeSupport. The method is called once before any Lambda invocations are made.If the users set the memory max memory settings themselves, for example using the
DOTNET_GCHeapHardLimit, to a value less than what Lambda function is configured for then theAdjustMemorySettingswill return making no adjustments. Users might now they will run other processes in the background that will take away some of the memory and so tell .NET it has to use less then the full function's memory setting.New integration tests were added to confirm the memory settings. The tests only work for .NET 8. If the test run for .NET 6 they will with the Lambda function thinking it has more memory then it really does have. These were the first .NET 8 integration tests added for RuntimeSupport and the integration tests need to be reworked a bit to support both .NET 6 and .NET 8 integration tests.