Because you opened the semaphore file for writing, but haven't yet written to it, it's just been erased.

Except that he's never (in the shown code, anyway) writing to the semaphore file. He's using a separate, presumably always-empty, file as the semaphore and is always opening the counter file in read or append... except possibly in writedata.

bbfu
Black flowers blossom
Fearless on my breath