Memcache stats understanding

Question

Memcache telnet interface has command called STATS, it shows a lot of numbers, where can I read what does it mean ? how to analyze them ? how much cache usage is ef

Answer 1

The updated documentation for this is found at https://github.com/memcached/memcached/blob/master/doc/protocol.txt.

|-----------------------+---------+-------------------------------------------|
| Name                  | Type    | Meaning                                   |
|-----------------------+---------+-------------------------------------------|
| pid                   | 32u     | Process id of this server process         |
| uptime                | 32u     | Number of secs since the server started   |
| time                  | 32u     | current UNIX time according to the server |
| version               | string  | Version string of this server             |
| pointer_size          | 32      | Default size of pointers on the host OS   |
|                       |         | (generally 32 or 64)                      |
| rusage_user           | 32u.32u | Accumulated user time for this process    |
|                       |         | (seconds:microseconds)                    |
| rusage_system         | 32u.32u | Accumulated system time for this process  |
|                       |         | (seconds:microseconds)                    |
| curr_items            | 64u     | Current number of items stored            |
| total_items           | 64u     | Total number of items stored since        |
|                       |         | the server started                        |
| bytes                 | 64u     | Current number of bytes used              |
|                       |         | to store items                            |
| max_connections       | 32u     | Max number of simultaneous connections    |
| curr_connections      | 32u     | Number of open connections                |
| total_connections     | 32u     | Total number of connections opened since  |
|                       |         | the server started running                |
| rejected_connections  | 64u     | Conns rejected in maxconns_fast mode      |
| connection_structures | 32u     | Number of connection structures allocated |
|                       |         | by the server                             |
| reserved_fds          | 32u     | Number of misc fds used internally        |
| cmd_get               | 64u     | Cumulative number of retrieval reqs       |
| cmd_set               | 64u     | Cumulative number of storage reqs         |
| cmd_flush             | 64u     | Cumulative number of flush reqs           |
| cmd_touch             | 64u     | Cumulative number of touch reqs           |
| get_hits              | 64u     | Number of keys that have been requested   |
|                       |         | and found present                         |
| get_misses            | 64u     | Number of items that have been requested  |
|                       |         | and not found                             |
| get_expired           | 64u     | Number of items that have been requested  |
|                       |         | but had already expired.                  |
| get_flushed           | 64u     | Number of items that have been requested  |
|                       |         | but have been flushed via flush_all       |
| delete_misses         | 64u     | Number of deletions reqs for missing keys |
| delete_hits           | 64u     | Number of deletion reqs resulting in      |
|                       |         | an item being removed.                    |
| incr_misses           | 64u     | Number of incr reqs against missing keys. |
| incr_hits             | 64u     | Number of successful incr reqs.           |
| decr_misses           | 64u     | Number of decr reqs against missing keys. |
| decr_hits             | 64u     | Number of successful decr reqs.           |
| cas_misses            | 64u     | Number of CAS reqs against missing keys.  |
| cas_hits              | 64u     | Number of successful CAS reqs.            |
| cas_badval            | 64u     | Number of CAS reqs for which a key was    |
|                       |         | found, but the CAS value did not match.   |
| touch_hits            | 64u     | Number of keys that have been touched     |
|                       |         | with a new expiration time                |
| touch_misses          | 64u     | Number of items that have been touched    |
|                       |         | and not found                             |
| auth_cmds             | 64u     | Number of authentication commands         |
|                       |         | handled, success or failure.              |
| auth_errors           | 64u     | Number of failed authentications.         |
| idle_kicks            | 64u     | Number of connections closed due to       |
|                       |         | reaching their idle timeout.              |
| evictions             | 64u     | Number of valid items removed from cache  |
|                       |         | to free memory for new items              |
| reclaimed             | 64u     | Number of times an entry was stored using |
|                       |         | memory from an expired entry              |
| bytes_read            | 64u     | Total number of bytes read by this server |
|                       |         | from network                              |
| bytes_written         | 64u     | Total number of bytes sent by this server |
|                       |         | to network                                |
| limit_maxbytes        | size_t  | Number of bytes this server is allowed to |
|                       |         | use for storage.                          |
| accepting_conns       | bool    | Whether or not server is accepting conns  |
| listen_disabled_num   | 64u     | Number of times server has stopped        |
|                       |         | accepting new connections (maxconns).     |
| time_in_listen_disabled_us                                                  |
|                       | 64u     | Number of microseconds in maxconns.       |
| threads               | 32u     | Number of worker threads requested.       |
|                       |         | (see doc/threads.txt)                     |
| conn_yields           | 64u     | Number of times any connection yielded to |
|                       |         | another due to hitting the -R limit.      |
| hash_power_level      | 32u     | Current size multiplier for hash table    |
| hash_bytes            | 64u     | Bytes currently used by hash tables       |
| hash_is_expanding     | bool    | Indicates if the hash table is being      |
|                       |         | grown to a new size                       |
| expired_unfetched     | 64u     | Items pulled from LRU that were never     |
|                       |         | touched by get/incr/append/etc before     |
|                       |         | expiring                                  |
| evicted_unfetched     | 64u     | Items evicted from LRU that were never    |
|                       |         | touched by get/incr/append/etc.           |
| evicted_active        | 64u     | Items evicted from LRU that had been hit  |
|                       |         | recently but did not jump to top of LRU   |
| slab_reassign_running | bool    | If a slab page is being moved             |
| slabs_moved           | 64u     | Total slab pages moved                    |
| crawler_reclaimed     | 64u     | Total items freed by LRU Crawler          |
| crawler_items_checked | 64u     | Total items examined by LRU Crawler       |
| lrutail_reflocked     | 64u     | Times LRU tail was found with active ref. |
|                       |         | Items can be evicted to avoid OOM errors. |
| moves_to_cold         | 64u     | Items moved from HOT/WARM to COLD LRU's   |
| moves_to_warm         | 64u     | Items moved from COLD to WARM LRU         |
| moves_within_lru      | 64u     | Items reshuffled within HOT or WARM LRU's |
| direct_reclaims       | 64u     | Times worker threads had to directly      |
|                       |         | reclaim or evict items.                   |
| lru_crawler_starts    | 64u     | Times an LRU crawler was started          |
| lru_maintainer_juggles                                                      |
|                       | 64u     | Number of times the LRU bg thread woke up |
| slab_global_page_pool | 32u     | Slab pages returned to global pool for    |
|                       |         | reassignment to other slab classes.       |
| slab_reassign_rescues | 64u     | Items rescued from eviction in page move  |
| slab_reassign_evictions_nomem                                               |
|                       | 64u     | Valid items evicted during a page move    |
|                       |         | (due to no free memory in slab)           |
| slab_reassign_chunk_rescues                                                 |
|                       | 64u     | Individual sections of an item rescued    |
|                       |         | during a page move.                       |
| slab_reassign_inline_reclaim                                                |
|                       | 64u     | Internal stat counter for when the page   |
|                       |         | mover clears memory from the chunk        |
|                       |         | freelist when it wasn't expecting to.     |
| slab_reassign_busy_items                                                    |
|                       | 64u     | Items busy during page move, requiring a  |
|                       |         | retry before page can be moved.           |
| slab_reassign_busy_deletes                                                  |
|                       | 64u     | Items busy during page move, requiring    |
|                       |         | deletion before page can be moved.        |
| log_worker_dropped    | 64u     | Logs a worker never wrote due to full buf |
| log_worker_written    | 64u     | Logs written by a worker, to be picked up |
| log_watcher_skipped   | 64u     | Logs not sent to slow watchers.           |
| log_watcher_sent      | 64u     | Logs written to watchers.                 |
|-----------------------+---------+-------------------------------------------|