Hi,
> From: André Warnier [mailto:a...@ice-sa.com]
> Subject: Re: [OT] Cannot cleanly undeploy a web application
>
> I believe that the underlying issue here is the difference in behaviour
> between Windows
> and Unix/Linux, with regard to a file opened by one process, when another
> process tries to
> delete the file.
> Unix/Linux allow this. The file entry in the directory is deleted, the
> process deleting it
> gets no error. The file itself is not deleted, and the process which has it
> open still has
> a handle to the file and can continue to access it.
> Under Windows however, the process trying to delete the file gets an error,
> at the very
> moment of the "delete".
I just wanted to add something:
The Unix behavior you describe is also possible under Windows. It depends on
the "file share" flag that is used to open a file.
I don't know how this works in the native WinAPI, but if you try the following
C# code for example (.Net) to read from a (big) file:
using (Stream s = new FileStream("C:\\MyBigFile.bin", FileMode.Open,
FileAccess.Read, FileShare.Delete | FileShare.Read)) {
byte[] buf = new byte[128];
int read;
while ((read = s.Read(buf, 0, buf.Length)) > 0) {
Console.WriteLine("Read: " + read + " bytes.");
Thread.Sleep(2000); // wait 2 seconds
}
}
Then you can delete the file while it is still opened and the program reads
from it. If you look at the free space of the drive, you will see that the
space that the file uses is not yet available. As soon as you close the process
/ cancel the reading, the space will become available.
It seems that most programs don't open a file that way - that is why an error
occurs when trying to delete such a file. However, I don't know why most
programs (or a Java InputStream etc.) open a file for reading without
specifying such a file share flag (E.g., in the above code example, if you use
a FileStream constructor that doesn't specify a FileShare flag, the file cannot
be deleted from other processes while it is opened). Maybe it is a design
principle in Windows to not be able to delete a opened file by default, so that
a user doesn't accidentally delete a file on which he is still working... but I
don't know.
Regards,
Konstantin Preißer
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