Is there a way to check if a file is currently open somewhere?

New to Julia
1

I have a big simulation file being in process of written, and I need to know when it stops being written.

Kind regards

2

lsof on Linux. For other platforms, search the web for examples of emulating lsof.

3

It seems like think the built in file watching API should be able to do this, but I wasn’t able to come up with an example that worked.

Here is a solution using inotify (you may need to apt install inotify-tools or the equivalent for your distro).
In one terminal, start a process writing to the file:

$ (while true; do echo hello; sleep 1; done) > /tmp/writing.txt

Then, in a julia repl:

julia> run(`inotifywait -e close_write /tmp/writing.txt`)
Setting up watches.
Watches established.

Switch back to the first terminal and interrupt the writing process with Ctrl-C, you should see this in the julia repl:

/tmp/writing.txt CLOSE_WRITE,CLOSE
Process(`inotifywait -e close_write /tmp/writing.txt`, ProcessExited(0))
4

I couldn’t get it to work either, but as you say FileWatching should be able to do it, see the help:

help?> poll_fd
search: poll_fd poll_file

  poll_fd(fd, timeout_s::Real=-1; readable=false, writable=false)

  Monitor a file descriptor fd for changes in the read or write availability, and with a timeout given by timeout_s
  seconds.

  The keyword arguments determine which of read and/or write status should be monitored; at least one of them must be
  set to true.

  The returned value is an object with boolean fields readable, writable, and timedout, giving the result of the
  polling.

" Monitor a file descriptor fd for changes in the read or write availability, … "

I unfortunately need the solution for windows, yours is Linux as far as I can see :confused:

Kind regards

5

Why not just write some “computation finished” token to the end of the file when the simulation is done?

6

I often write another file that summarizes the simulation results (also status, like finishing time) when the simulation is done.

1 Like
7

It is because I do not control the simulation output, I only start the simulation. It is some other software I am using. Since it generates big data files, I wish to post-process the simulation as it runs. Therefore I need to be able to detect when a simulation file has been generated so I can start processing it.

Kind regards