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c#.nettimerfilesystemwatcher

Reading a file without preventing other processes from reading it at the same time

I'm making a little app in C#/.NET that watch for the creation of a file and when it is created it gets its content, parse it and write it in another file.

Everything is working fine so far. But the problem is : there's another process that watch for this file as well. My process is only READING the file while the second one reads it and then DELETES it.

My application is making its job but when it reads the file, the other process can't read it and totally crashes (Not made by me and don't have the sources to fix it).

My application is running very fast and other open the files for a very little time to get the content and put it in a variable so it could close the file faster and then parse the content of the file which is in the variable.

I clearly don't know how but I'd like to be able to read the file and let the other read the file at the same time without any hiccups. Is it possible? I still think that there will be a problem about the fact that the file is being deleted after the other app is done parsing it...

Any suggestions or ideas?

Thanks very much!

Solution

  • KISS: Can you have the file created in a location which the first program isn't looking at, but your software is - and when you are done processing it you then move it to the current location where the first program is looking?

    Otherwise: You are going to have contention since it's going to be a race to see which process actually "notices" the file first and begins working.

    I'm assuming you also don't have any control over the process creating the file?

    In that case you might look at PsSuspend or PauseSp - if you can control the other process by suspending it until you are ready for it (done with the file) then that might be viable. Not sure how robust this would be.

    There's also still the potential race condition of "noticing" the file and performing an action (whatever it is) - keeping the other process paused perpetually until you want it to run (or killing it and starting it) is the only completely deterministic way to achieve what you want within the constraints.