=== run 2: outq snapshot mid-hang via second process is impossible (cdev exclusive); use sizes 64 vs 65 boundary:
n=64 real=	6.04s real		0.00s user		0.00s sys rc=124
n=65 real=	6.05s real		0.00s user		0.00s sys rc=124
n=128 real=	6.04s real		0.00s user		0.00s sys rc=124
n=1024 real=	6.04s real		0.00s user		0.00s sys rc=124
=== 2s-settle control (same 1024 bytes, sleep before close):