Escribir en un FileStream se comporta de manera extraña, según lo observado por el monitor de proceso

Question

Estoy usando FileStream para escribir en un archivo y ver las llamadas al sistema subyacente usando Process Monitor. Tengo problemas con algunos problemas de bloqueo de archivos en una implementación de producción, por lo que estoy mirando los detalles de cerca.

Este código de ejemplo:

 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(); 
     } 

ocasionan los siguientes sistemas de llamadas:

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 

Se espera que las tres primeras llamadas IO (crear, escribir, cierre), pero el proceso continúa lea el archivo una docena más de veces y ábralo y ábralo repetidamente.

Ahora he observado este comportamiento en Win XP SP2 y Win 2003 x64. Sin embargo, mi máquina con Windows Vista en casa se comporta como se esperaba (solo las primeras tres líneas).

¿Alguna pista sobre por qué esto sucede en los tiempos de ejecución que no son de Vista?

Answer 1

Una posibilidad es que tenga un antivirus instalado que se inyecte en cada proceso en ejecución?