[LAD] Re: jack_is_realtime(client) issues

On August 24, 2025 4:15:37 PM GMT+02:00, Hermann Meyer <brummer--S0/[email protected]> wrote:
>Hi
>
>I running into issues with the jack_is_realtime(client) currently. The issue is, when the user didn't have permission to run real-time tasks, jackd starts with no real-time permission but jack_is_realtime(client) reports true as soon the -R is in the jackd commandline. The same is true for jack_client_real_time_priority(client). This call reports the real-time priority given in the command line, but not the one in use. So, when jackd starts without real-time priority, but -R is given on the command-line, it reports the priority from jackdrc while it runs at SCHED_OTHER without any priority.
>
>Now, when I want to start my own threads I cant relay on the values reported by jackd, which render the functions useless.
>
>I need to run my own tests in order to check if real-time priority could be set by the user or not.
>
>regards
>
>hermann
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The documentation for this API call is a little unclear about what it really does:

<https://jackaudio.org/api/group__ClientFunctions.html#ga15719a4abdcc5fa8415167dd6ed6512c>

And one could consider the implementation to be conforming.

I would still consider this a bug though - but rather both in the documentation and the implementation.

Also wasn't there a difference between jack1 and jack2 in how they handle the failure to acquire rt scheduling? IIRC jack1 errors out while jack2 just prints a warning.

With jack1 the behaviour then would be precisely what one wants since -R and having this call returning 1 actually implies having rt scheduling. With jack2 that's not the case anymore.


Kind regardsv
FPS
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