couchbase server does not raise an alert when hashtable is mostly consumed by key+metadata

Amount of active item metadata consuming RAM in this bucket (measured from vb_active_meta_data_memory)

ui right now is using vb_active_meta_data_memory.

in the below example there are 20M items on a node where high watermark 3.1 GB , 90 % of items are less than 32 bytes. so memory is mostly used by the key+metadata

curr_items: 10398801
curr_items_tot: 20800098
curr_temp_items: 0
ep_access_scanner_num_items: 0
ep_chk_max_items: 5000
ep_diskqueue_items: 0
ep_items_rm_from_checkpoints: 22036291
ep_total_del_items: 2050118
ep_total_new_items: 23366776
ep_uncommitted_items: 0
ep_warmup_min_items_threshold: 100
vb_active_curr_items: 10398801
vb_active_num_ref_items: 840854
vb_pending_curr_items: 0
vb_pending_num_ref_items: 0
vb_replica_curr_items: 10401297
vb_replica_num_ref_items: 654973

couchbase-macbook-13:management farshid$ ./cbstats 10.3.3.59:11210 all | grep mem
ep_diskqueue_memory: 0
ep_mem_high_wat: 3145728000
ep_mem_low_wat: 2516582400
ep_mem_tracker_enabled: true
ep_mutation_mem_threshold: 0
ep_warmup_min_memory_threshold: 100
mem_used: 3272857616
vb_active_ht_memory: 50398208
vb_active_itm_memory: 987886095
vb_active_meta_data_memory: 904695687
vb_active_perc_mem_resident: 0
vb_active_queue_memory: 0
vb_pending_ht_memory: 0
vb_pending_itm_memory: 0
vb_pending_meta_data_memory: 0
vb_pending_perc_mem_resident: 0
vb_pending_queue_memory: 0
vb_replica_ht_memory: 61012880
vb_replica_itm_memory: 988123215
vb_replica_meta_data_memory: 904912839
vb_replica_perc_mem_resident: 0
vb_replica_queue_memory: 0

couchbase-macbook-13:management farshid$ ./cbstats 10.3.3.59:11210 memory
bytes: 3272854448
ep_kv_size: 2225610486
ep_max_data_size: 4194304000
ep_mem_high_wat: 3145728000
ep_mem_low_wat: 2516582400
ep_mem_tracker_enabled: true
ep_oom_errors: 0
ep_overhead: 113025616
ep_tmp_oom_errors: 0
ep_value_size: 332801568
mem_used: 3272854448
tcmalloc_current_thread_cache_bytes: 2953344
tcmalloc_max_thread_cache_bytes: 4194304
tcmalloc_unmapped_bytes: 0
total_allocated_bytes: 3347676192
total_fragmentation_bytes: 53306336
total_free_bytes: 707207168
total_heap_bytes: 4108189696