[LAD] ALSA multi plugin and JACK xrun callbacks

[Jörn Nettingsmeier]

On 01/14/2011 11:12 PM, Jörn Nettingsmeier wrote:
> On 01/14/2011 10:39 PM, Jörn Nettingsmeier wrote:
> 
>> i had it crash once when loading a really demanding session, but with
>> another average ardour project, it has now played fine and without
>> glitches for 10 minutes or so, while the xrun count goes through the roof.
> 
> alas. i spoke to soon:
> 
> after i added a 6x1 convolver and an ambdec instance
> jack2 bails out reproducibly after a couple minutes more, with a
> "floating point exception". so more testing.
> 
> meanwhile, i'd like to know what these xruns are, and i wouldn't be too
> surprised if the eventual crash is actually related to the message
> buffer or some internal error counter wrapping...

jack2 gets nervous when i use a session with four jconvolver instances:

JackPosixMutex::Unlock res = 1
Unknown request 4294967295
jackd: ../common/JackGraphManager.cpp:45: void
Jack::JackGraphManager::AssertPort(jack_port_id_t): Assertion
`port_index < fPortMax' failed.
Aborted

the cpu is not maxed out, afaics.

tschack handles this scenario just fine, and it doesn't spew error
messages on the console. if i monitor it in qjackctl, the xrun count
increases at the usual rate, though.

btw: qjackctl becomes a major cpu burden in this pathological case.
lookes like it's the error messages. i've seen it at up to 40% of one core.