kill $scheme_pid;

You probably meant something like 

    kill INT => $scheme_pid;

[download]

As you have it, kill would try to send the signal number $scheme_pid to no processes — so nothing happens, effectively...

As a result, your code hangs in the implicit wait behind close SCHEME, because the child process is still alive.

In reply to Re^6: Cannot catch ALRM signal for timeout by almut
in thread Cannot catch ALRM signal for timeout by Magice

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