When the number of open files is reached in the system, vhost may encounter a failure in socket call and return from vhost-user-process. The return terminates all attempts of incoming socket connections in the future, even if the condition is reconciled. Here is a snapshot of what may happen to vhost-user-input and vhost-user-process when that happens.

DBGvpp# 0: vhost_user_process:2385: Critical: Could not open unix socket

DBGvpp# sh run
Time 157.8, average vectors/node 0.00, last 128 main loops 0.00 per node 0.00
vector rates in 0.0000e0, out 0.0000e0, drop 0.0000e0, punt 0.0000e0
Name State Calls Vectors Suspends Clocks Vectors/Call
acl-plugin-fa-cleaner-process any wait 0 0 314 3.99e3 0.00
admin-up-down-process event wait 0 0 1 1.32e4 0.00
api-rx-from-ring any wait 0 0 9 5.64e5 0.00
bfd-process event wait 0 0 1 1.38e4 0.00
cdp-process any wait 0 0 38 1.47e4 0.00
dhcp-client-process any wait 0 0 2 2.08e4 0.00
dpdk-ipsec-process done 1 0 0 8.39e4 0.00
dpdk-process any wait 0 0 53 3.79e4 0.00
fib-walk any wait 0 0 156203 1.60e3 0.00
flow-report-process any wait 0 0 1 1.74e4 0.00
gmon-process time wait 0 0 32 7.91e3 0.00
ikev2-manager-process any wait 0 0 157 4.67e3 0.00
ioam-export-process any wait 0 0 1 1.43e4 0.00
ip6-icmp-neighbor-discovery-ev any wait 0 0 157 5.12e3 0.00
l2fib-mac-age-scanner-process event wait 0 0 1 5.44e3 0.00
lisp-retry-service any wait 0 0 79 7.11e3 0.00
lldp-process event wait 0 0 1 3.48e5 0.00
snat-det-expire-walk done 1 0 0 2.37e9 0.00
startup-config-process done 1 0 1 2.43e4 0.00
udp-ping-process any wait 0 0 1 5.52e4 0.00
unix-cli-stdin active 0 0 3 2.51e8 0.00
unix-epoll-input polling 290400447 0 0 7.58e2 0.00
vhost-user-input disabled 13495126 0 0 9.46e2 0.00
vhost-user-process done 1 0 28 3.24e6 0.00
vpe-link-state-process event wait 0 0 9 1.15e4 0.00
vpe-oam-process any wait 0 0 77 4.82e3 0.00
vpe-route-resolver-process any wait 0 0 2 2.57e4 0.00
vxlan-gpe-ioam-export-process any wait 0 0 1 2.09e4 0.00
DBGvpp#