Escribir en un FileStream se comporta de forma extraña, como lo observa el monitor de proceso

Question

Estoy usando FileStream para escribir en un archivo, y veo las llamadas al sistema subyacente usando Monitor de proceso . Tengo problemas con algunos problemas de bloqueo de archivos en una implementación de producción, así 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();
        }

Causa las siguientes llamadas 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 

Se esperan las primeras tres llamadas IO (crear, escribir, cerrar), pero el proceso continúa leyendo el archivo una docena de veces más y lo abre y cierra 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 tres primeras líneas).

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

Answer 1

¿Una posibilidad es que tenga instalado un escáner de virus que se inyecte en cada proceso en ejecución?