I have some thing similar


I have a pair of DHCP serevrs running in a cluster on ubuntu 20.04, All worked perfectly until recently, when they started stopping with code=killed, status=6/ABRT.
This is being fixed by 

https://bugs.launchpad.net/bugs/1870729

However now one stops after a few hours with the following errors. One can stay on line but not both.




Syslog shows 
Apr 10 17:20:15 dhcp-primary sh[6828]: ../../../../lib/isc/unix/socket.c:3361: INSIST(!sock->pending_send) failed, back trace
Apr 10 17:20:15 dhcp-primary sh[6828]: #0 0x7fbe78702a4a in ??
Apr 10 17:20:15 dhcp-primary sh[6828]: #1 0x7fbe78702980 in ??
Apr 10 17:20:15 dhcp-primary sh[6828]: #2 0x7fbe7873e7e1 in ??
Apr 10 17:20:15 dhcp-primary sh[6828]: #3 0x7fbe784e5609 in ??
Apr 10 17:20:15 dhcp-primary sh[6828]: #4 0x7fbe78621103 in ??


nothing in kern.log


apport.log shows
ERROR: apport (pid 6850) Fri Apr 10 17:20:15 2020: called for pid 6828, signal 6, core limit 0, dump mode 2
ERROR: apport (pid 6850) Fri Apr 10 17:20:15 2020: not creating core for pid with dump mode of 2
ERROR: apport (pid 6850) Fri Apr 10 17:20:15 2020: executable: /usr/sbin/dhcpd (command line "dhcpd -user dhcpd -group dhcpd -f -4 -pf /run/dhcp-server/dhcpd.pid -cf /etc/dhcp/dhcpd.conf")
ERROR: apport (pid 6850) Fri Apr 10 17:20:15 2020: is_closing_session(): no DBUS_SESSION_BUS_ADDRESS in environment
ERROR: apport (pid 6850) Fri Apr 10 17:20:15 2020: wrote report /var/crash/_usr_sbin_dhcpd.0.crash



/var/crash/_usr_sbin_dhcpd.0.crash shows

ProblemType: Crash
Architecture: amd64
CrashCounter: 1
Date: Fri Apr 10 17:20:15 2020
DistroRelease: Ubuntu 20.04
ExecutablePath: /usr/sbin/dhcpd
ExecutableTimestamp: 1586210315
ProcCmdline: dhcpd -user dhcpd -group dhcpd -f -4 -pf /run/dhcp-server/dhcpd.pid -cf /etc/dhcp/dhcpd.conf
ProcEnviron: Error: [Errno 13] Permission denied: 'environ'
ProcMaps: Error: [Errno 13] Permission denied: 'maps'
ProcStatus:
 Name:  dhcpd
 Umask: 0022
 State: D (disk sleep)
 Tgid:  6828
 Ngid:  0
 Pid:   6828
 PPid:  1
 TracerPid:     0
 Uid:   113     113     113     113
 Gid:   118     118     118     118
 FDSize:        128
 Groups:
 NStgid:        6828
 NSpid: 6828
 NSpgid:        6828
 NSsid: 6828
 VmPeak:          236244 kB
 VmSize:          170764 kB
 VmLck:        0 kB
 VmPin:        0 kB
 VmHWM:    12064 kB
 VmRSS:    12064 kB
 RssAnon:           5940 kB
 RssFile:           6124 kB
 RssShmem:             0 kB
 VmData:           30792 kB
 VmStk:      132 kB
 VmExe:      592 kB
 VmLib:     5424 kB
 VmPTE:       76 kB
 VmSwap:               0 kB
 HugetlbPages:         0 kB
 CoreDumping:   1
 THP_enabled:   1
 Threads:       4
 SigQ:  0/7609
 SigPnd:        0000000000000000
 ShdPnd:        0000000000000000
 SigBlk:        0000000000000000
 SigIgn:        0000000000001000
 SigCgt:        0000000180000000
 CapInh:        0000000000000000
 CapPrm:        0000000000000000
 CapEff:        0000000000000000
 CapBnd:        0000003fffffffff
 CapAmb:        0000000000000000
 NoNewPrivs:    0
 Seccomp:       0
 Speculation_Store_Bypass:      thread vulnerable
 Cpus_allowed:  3
 Cpus_allowed_list:     0-1
 Mems_allowed:  00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,0000
0000,00000000,00000000,00000001
 Mems_allowed_list:     0
 voluntary_ctxt_switches:       111
 nonvoluntary_ctxt_switches:    144
Signal: 6
Uname: Linux 5.4.0-21-generic x86_64
UserGroups: