This works fine most of the time, but occasionally under heavy network load, the echo response is not immediately available, and the recvmsg fails with EAGAIN, leading to a false positive down event ("not running") on the resource:
Mar 28 18:53:59 sp1 pacemaker-schedulerd[41843]: warning: Unexpected result (not running) was recorded for monitor of p_vip_neth0_v6_1 on sp1 at Mar 28 00:02:38 2023
The "monitor" action of IPv6addr is sending an ICMPv6 echo request to the given local address: https://github.com/ClusterLabs/resource-agents/blob/d6b954890b496fcdd8a76d7c2dd44a36fa0ad42c/heartbeat/IPv6addr.c#L630
and is the expecting to receive the respective echo response immediately, without delay, using
MSG_DONTWAIT: https://github.com/ClusterLabs/resource-agents/blob/d6b954890b496fcdd8a76d7c2dd44a36fa0ad42c/heartbeat/IPv6addr.c#L647This works fine most of the time, but occasionally under heavy network load, the echo response is not immediately available, and the
recvmsgfails withEAGAIN, leading to a false positive down event ("not running") on the resource: