Escrever para um FileStream se comporta estranhamente, conforme observado pelo Monitor de Processos
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05-07-2019 - |
Pergunta
Estou usando o Filestream para escrever em um arquivo e assistindo às chamadas do sistema subjacente usando Monitor do processo. Estou tendo problemas com alguns problemas de travamento de arquivos em uma implantação de produção, por isso estou olhando de perto os detalhes.
Este código de amostra:
using (FileStream fs = new FileStream("c:\\temp\\test.txt", FileMode.Create, FileAccess.Write, FileShare.Read))
{
fs.Write(new byte[] { 1, 2, 3, 4, 5 }, 0, 5);
fs.Close();
}
Causa as seguintes chamadas de sistemas:
9:27:09.4561092 AM ConsoleApplication1.vshost.exe 2320 CreateFile C:\temp\test.txt SUCCESS Desired Access: Generic Read/Write, Disposition: OverwriteIf, Options: Synchronous IO Non-Alert, Non-Directory File, Open No Recall, Attributes: n/a, ShareMode: Read, AllocationSize: 0, OpenResult: Overwritten
9:27:12.2217409 AM ConsoleApplication1.vshost.exe 2320 WriteFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2219901 AM ConsoleApplication1.vshost.exe 2320 CloseFile C:\temp\test.txt SUCCESS
9:27:12.2234484 AM ConsoleApplication1.vshost.exe 2320 CreateFile C:\temp\test.txt SUCCESS Desired Access: Generic Read, Write Attributes, Disposition: Open, Options: Synchronous IO Non-Alert, Non-Directory File, Complete If Oplocked, Random Access, Attributes: N, ShareMode: Read, Write, Delete, AllocationSize: n/a, OpenResult: Opened
9:27:12.2248664 AM ConsoleApplication1.vshost.exe 2320 QueryBasicInformationFile C:\temp\test.txt SUCCESS CreationTime: 10/29/2008 9:04:14 AM, LastAccessTime: 10/29/2008 9:27:12 AM, LastWriteTime: 10/29/2008 9:27:12 AM, ChangeTime: 10/29/2008 9:27:12 AM, FileAttributes: A
9:27:12.2250075 AM ConsoleApplication1.vshost.exe 2320 SetBasicInformationFile C:\temp\test.txt SUCCESS CreationTime: -1, LastAccessTime: -1, LastWriteTime: -1, ChangeTime: -1, FileAttributes: n/a
9:27:12.2255889 AM ConsoleApplication1.vshost.exe 2320 QueryStandardInformationFile C:\temp\test.txt SUCCESS AllocationSize: 8, EndOfFile: 5, NumberOfLinks: 1, DeletePending: False, Directory: False
9:27:12.2257571 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2259825 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2261588 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2265161 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 2
9:27:12.2268237 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2271332 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2272841 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2274779 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2276249 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2278766 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2282577 AM ConsoleApplication1.vshost.exe 2320 ReadFile C:\temp\test.txt SUCCESS Offset: 0, Length: 5
9:27:12.2284476 AM ConsoleApplication1.vshost.exe 2320 QueryFileInternalInformationFile C:\temp\test.txt SUCCESS IndexNumber: 0x2d000000016b88
9:27:12.2286183 AM ConsoleApplication1.vshost.exe 2320 CloseFile C:\temp\test.txt SUCCESS
9:27:12.2288759 AM ConsoleApplication1.vshost.exe 2320 CreateFile C:\temp\test.txt SUCCESS Desired Access: Read Attributes, Write Attributes, Disposition: Open, Options: , Attributes: n/a, ShareMode: Read, Write, Delete, AllocationSize: n/a, OpenResult: Opened
9:27:12.2305722 AM ConsoleApplication1.vshost.exe 2320 QueryBasicInformationFile C:\temp\test.txt SUCCESS CreationTime: 10/29/2008 9:04:14 AM, LastAccessTime: 10/29/2008 9:27:12 AM, LastWriteTime: 10/29/2008 9:27:12 AM, ChangeTime: 10/29/2008 9:27:12 AM, FileAttributes: A
9:27:12.2307379 AM ConsoleApplication1.vshost.exe 2320 CloseFile C:\temp\test.txt SUCCESS
As três primeiras chamadas de IO são esperadas (Criar, escrever, fechar), mas o processo continua lendo o arquivo uma dúzia a mais vezes e abre e feche repetidamente.
Agora observei esse comportamento no Win XP SP2 e Win 2003 x64. No entanto, minha máquina Windows Vista em casa se comporta conforme o esperado (apenas as três primeiras linhas).
Alguma pista sobre por que isso está acontecendo no não-Vista RunTimes?
Solução
Uma possibilidade é que você tenha um scanner de vírus instalado que se injete em cada processo de corrida?