According to https://github.com/jackaudio/jack2/blob/6bacf6e1db975e5738821bf4abe20314f5e38283/common/JackTypes.h#L45-L50

typedef enum {
    NotTriggered,
    Triggered,
    Running,
    Finished,
} jack_client_state_t;

I don't understand any of jack_client_state_t.

I usually see xruns with state = Triggered or Running.

I'm incrementally increasing period size of zita-a2j and zita-j2a in order to eliminate xruns.