query engine process killed due to OOM in spock longevity

2 days into longevity on 5.0.0-1676 - query engine process killed many times due to OOM:

Jan 18 22:27:28 ubuntu14-04 kernel: [727106.556465] Out of memory: Kill process 31922 (cbq-engine) score 952 or sacrifice child
Jan 18 22:27:28 ubuntu14-04 kernel: [727106.557668] Killed process 31922 (cbq-engine) total-vm:32278436kB, anon-rss:29358584kB, file-rss:0kB
Jan 19 01:30:41 ubuntu14-04 kernel: [738099.715710] TCP: request_sock_TCP: Possible SYN flooding on port 8093. Sending cookies. Check SNMP counters.
Jan 19 01:30:53 ubuntu14-04 kernel: [738111.887500] cbq-engine invoked oom-killer: gfp_mask=0x201da, order=0, oom_score_adj=0
Jan 19 01:30:53 ubuntu14-04 kernel: [738111.887506] cbq-engine cpuset=/ mems_allowed=0
Jan 19 01:30:53 ubuntu14-04 kernel: [738111.887512] CPU: 1 PID: 32143 Comm: cbq-engine Tainted: G L 3.19.0-25-generic #26~14.04.1-Ubuntu
Jan 19 01:30:53 ubuntu14-04 kernel: [738111.887513] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1~cloud0 04/01/2014

attaching kern.log and cbcollect logs - please investigate