indexer process killed due to OOM in spock longevity

2 days into longevity on 5.0.0-1676 - indexer process has been killed many times due to OOM :

Jan 18 20:08:04 kvm-s63702 kernel: [719664.027226] Out of memory: Kill process 22189 (indexer) score 945 or sacrifice child
Jan 18 20:08:04 kvm-s63702 kernel: [719664.030419] Killed process 22189 (indexer) total-vm:61709596kB, anon-rss:29123636kB, file-rss:1800kB
Jan 18 20:10:43 kvm-s63702 kernel: [719823.750927] indexer invoked oom-killer: gfp_mask=0x280da, order=0, oom_score_adj=0
Jan 18 20:10:43 kvm-s63702 kernel: [719823.750938] indexer cpuset=/ mems_allowed=0
Jan 18 20:10:43 kvm-s63702 kernel: [719823.750958] CPU: 1 PID: 25242 Comm: indexer Not tainted 3.19.0-25-generic #26~14.04.1-Ubuntu
Jan 18 20:10:43 kvm-s63702 kernel: [719823.750961] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Jan 18 20:10:43 kvm-s63702 kernel: [719823.750965] 0000000000000000 ffff8806549479d8 ffffffff817aed00 0000000000000000
Jan 18 20:10:43 kvm-s63702 kernel: [719823.750970] ffff88061ea3bae0 ffff880654947a78 ffffffff817a9c3f ffff880654947a98
Jan 18 20:10:43 kvm-s63702 kernel: [719823.750973] 0000000000000000 0000000000000014 0000000000000002 ffff880654947ac8

attaching kern.log from indexer node and cbcollect logs