Azure函数内存不足异常

Question

我正在从Blob中读取PDF文件，并使用Azure Function进行一些操作。当PDF大小为1.5GB（或更大）时，我的azure函数在代码命中以下命令后立即失败，并出现内存不足异常。

var ms = new MemoryStream();
log.LogInformation("Converting this File to memorystream : " + blob.Uri);
blob.DownloadToStream(ms);  //Failes HERE.

我尝试增加计划，切换到EP3（14 GB内存+ 840 ACU）。但是问题还是一样。我还需要更改其他配置吗？如何护理它。

Microsoft.Azure.Storage.StorageException: Exception of type 'System.OutOfMemoryException' was thrown.
 ---> System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown.
   at System.IO.MemoryStream.set_Capacity(Int32 value)
   at System.IO.MemoryStream.EnsureCapacity(Int32 value)
   at System.IO.MemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count)
   at System.IO.MemoryStream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.Azure.Storage.Core.Util.AsyncStreamCopier`1.StartCopyStreamAsyncHelper(Nullable`1 copyLength, Nullable`1 maxLength, CancellationToken token)
   at Microsoft.Azure.Storage.Core.Util.AsyncStreamCopier`1.StartCopyStreamAsync(Nullable`1 copyLength, Nullable`1 maxLength, CancellationToken cancellationToken)
   at Microsoft.Azure.Storage.Core.Executor.Executor.ExecuteAsync[T](RESTCommand`1 cmd, IRetryPolicy policy, OperationContext operationContext, CancellationToken token)
   --- End of inner exception stack trace ---
   at Microsoft.Azure.Storage.Core.Executor.Executor.ExecuteAsync[T](RESTCommand`1 cmd, IRetryPolicy policy, OperationContext operationContext, CancellationToken token)
   at Microsoft.Azure.Storage.Core.Executor.Executor.<>c__DisplayClass0_0`1.<ExecuteSync>b__0()
   at Microsoft.Azure.Storage.Core.Util.CommonUtility.RunWithoutSynchronizationContext[T](Func`1 actionToRun)
   at Microsoft.Azure.Storage.Core.Executor.Executor.ExecuteSync[T](RESTCommand`1 cmd, IRetryPolicy policy, OperationContext operationContext)
   at Microsoft.Azure.Storage.Blob.CloudBlob.DownloadRangeToStream(Stream target, Nullable`1 offset, Nullable`1 length, AccessCondition accessCondition, BlobRequestOptions options, OperationContext operationContext)
   at Microsoft.Azure.Storage.Blob.CloudBlob.DownloadToStream(Stream target, AccessCondition accessCondition, BlobRequestOptions options, OperationContext operationContext)

Answer 1

This blog听起来似乎已经确定了问题-MemoryStream使用int32来设置其容量，没有选择使用更大的数字。我无法完全将int32.MaxValue（2147483647）的值与指定大小（1.5GiB字节为1610612736字节）进行调和，但看起来足够接近罪魁祸首。该博客提出了一种向Blob存储中写入大量内容的解决方案，但我不认为这对于您的用例如何起作用。

如果您确实需要使用MemoryStream来满足您所使用的库的需求，那么将无法处理如此大的文件。