Hard Out Of Memory problem

It is the state after a problem occurred a month ago and then rebooted

set Item expire 3hour.

System free memory continues to decrease, and cache memory continues to increase
In the end, I’m having problems spitting out of memory.

Membase is used for session management in a server where traffic is high,
Operation is get, set, touch.

Bucket Log when occurred ‘out of memory’

accepting_conns 1
auth_cmds 134371
auth_errors 0
bucket_active_conns 3
bucket_conns 107
bytes_read 110303154414304
bytes_written 60239916710650
cas_badval 0
cas_hits 0
cas_misses 0
cmd_flush 2
cmd_get 397829942924
cmd_set 187845263529
conn_yields 265421003
connection_structures 127
curr_connections 114
curr_items 298885
curr_items_tot 11394317
daemon_connections 10
decr_hits 0
decr_misses 0
delete_hits 2223793
delete_misses 1011994
ep_bg_fetched 3403166
ep_bg_load 4253271459
ep_bg_load_avg 1249
ep_bg_max_load 2002143
ep_bg_max_wait 2039024
ep_bg_min_load 9
ep_bg_min_wait 10
ep_bg_num_samples 3403166
ep_bg_wait 2457149015
ep_bg_wait_avg 722
ep_commit_num 120552418
ep_commit_time 2
ep_commit_time_total 51599186153
ep_data_age 37
ep_data_age_highwat 194
ep_db_cleaner_status complete
ep_db_strategy multiMTVBDB
ep_dbinit 2
ep_dbshards 4
ep_diskqueue_drain 79468744130
ep_diskqueue_fill 80154321531
ep_diskqueue_items 685711445
ep_diskqueue_memory 60342607160
ep_diskqueue_pending 215393392281
ep_exp_pager_stime 3600
ep_expired 304819843418
ep_flush_all false
ep_flush_duration 53
ep_flush_duration_highwat 118
ep_flush_duration_total 60624495
ep_flush_preempts 0
ep_flusher_state running
ep_io_num_read 3403934
ep_io_num_write 77347933283
ep_io_read_bytes 974669708
ep_io_write_bytes 17182129482320
ep_item_begin_failed 0
ep_item_commit_failed 0
ep_item_flush_expired 1252844950
ep_item_flush_failed 0
ep_items_rm_from_checkpoints 5213067652
ep_kv_size 1830799526
ep_latency_arith_cmd 0
ep_latency_get_cmd 18446744072110945076
ep_latency_store_cmd 18446744072576254121
ep_max_data_size 2147483648
ep_max_txn_size 1000
ep_mem_high_wat 1610612736
ep_mem_low_wat 1288490188
ep_min_data_age 0
ep_num_active_non_resident 13831295
ep_num_checkpoint_remover_runs22047559
ep_num_eject_failures 190731162
ep_num_eject_replicas 120670510
ep_num_expiry_pager_runs 30638
ep_num_non_resident 21425829
ep_num_not_my_vbuckets 5898
ep_num_pager_runs 29810
ep_num_value_ejects 137905808
ep_onlineupdate false
ep_onlineupdate_revert_add 0
ep_onlineupdate_revert_delete 0
ep_onlineupdate_revert_update 0
ep_oom_errors 12568775
ep_overhead 101944842
ep_pending_ops 0
ep_pending_ops_max 0
ep_pending_ops_max_duration 0
ep_pending_ops_total 0
ep_queue_age_cap 900
ep_queue_size 55510
ep_storage_age 37
ep_storage_age_highwat 4294967295
ep_storage_type featured
ep_store_max_concurrency 10
ep_store_max_readers 9
ep_store_max_readwrite 1
ep_tap_bg_fetch_requeued 0
ep_tap_bg_fetched 0
ep_tap_keepalive 0
ep_tmp_oom_errors 0
ep_too_old 0
ep_too_young 134793
ep_total_cache_size 221298975667
ep_total_del_items 1253562651
ep_total_enqueued 80254262910
ep_total_new_items 1264963373
ep_total_persisted 78601495934
ep_uncommitted_items 1000
ep_value_size 21214817
ep_vb_total 768
ep_vbucket_del 1
ep_vbucket_del_avg_walltime 26932
ep_vbucket_del_fail 0
ep_vbucket_del_max_walltime 26932
ep_vbucket_del_total_walltime 26932
ep_version 1.7.1.1_39_g4bd26a3
ep_warmed_up 0
ep_warmup true
ep_warmup_dups 0
ep_warmup_oom 0
ep_warmup_thread complete
ep_warmup_time 3167194
get_hits 190094583698
get_misses 207735359226
incr_hits 0
incr_misses 0
libevent 2.0.11-stable
limit_maxbytes 67108864
listen_disabled_num 0
mem_used 1932744368
pid 3407
pointer_size 64
rejected_conns 0
rusage_system 10249039.648143
rusage_user 15039410.552072
tap_checkpoint_end_received 519001
tap_checkpoint_end_sent 518953
tap_checkpoint_start_received 10887519
tap_checkpoint_start_sent 10860346
tap_connect_received 3
tap_delete_received 245177624
tap_delete_sent 20122395
tap_flush_sent 6
tap_mutation_received 3855324228
tap_mutation_sent 3712983703
tap_opaque_received 368333
tap_opaque_sent 1477
threads 4
time 1477549972
total_connections 134490
uptime 110297716
vb_active_curr_items 298885
vb_active_eject 17235298
vb_active_ht_memory 6418432
vb_active_itm_memory 53824251
vb_active_num 256
vb_active_num_non_resident 13831295
vb_active_ops_create 1241765361
vb_active_ops_delete 1241467715
vb_active_ops_reject 134793
vb_active_ops_update 75137635355
vb_active_perc_mem_resident 0
vb_active_queue_age 2411147000
vb_active_queue_drain 78562139106
vb_active_queue_fill 78562061791
vb_active_queue_memory 5058064
vb_active_queue_pending 17693732
vb_active_queue_size 57478
vb_dead_num 0
vb_pending_curr_items 0
vb_pending_eject 0
vb_pending_ht_memory 0
vb_pending_itm_memory 0
vb_pending_num 0
vb_pending_num_non_resident 0
vb_pending_ops_create 0
vb_pending_ops_delete 0
vb_pending_ops_reject 0
vb_pending_ops_update 0
vb_pending_perc_mem_resident 0
vb_pending_queue_age 0
vb_pending_queue_drain 0
vb_pending_queue_fill 0
vb_pending_queue_memory 0
vb_pending_queue_pending 0
vb_pending_queue_size 0
vb_replica_curr_items 11095432
vb_replica_eject 120670510
vb_replica_ht_memory 77586464
vb_replica_itm_memory 1766029488
vb_replica_num 512
vb_replica_num_non_resident 7594534
vb_replica_ops_create 20074934
vb_replica_ops_delete 8986166
vb_replica_ops_reject 0
vb_replica_ops_update 852407463
vb_replica_perc_mem_resident 31
vb_replica_queue_age 1190959300254266000
vb_replica_queue_drain 906605024
vb_replica_queue_fill 1592259740
vb_replica_queue_memory 60337549096
vb_replica_queue_pending 215375698549
vb_replica_queue_size 685653967