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Memcached

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Memcached collector can collect the running status metrics from Memcached instances, and collect the metrics to the observation cloud to help monitor and analyze various abnormal situations of Memcached.

Config

Preconditions

  • Memcached version >= 1.5.0. Already tested version:
    • 1.5.x
    • 1.6.x

Collector Configuration

Go to the conf.d/db directory under the DataKit installation directory, copy memcached.conf.sample and name it memcached.conf. Examples are as follows:

[[inputs.memcached]]
  ## Servers' addresses.
  servers = ["localhost:11211"]
  # unix_sockets = ["/var/run/memcached.sock"]

  ## Set true to enable election
  election = true

  ## Collect extra stats
  # extra_stats = ["slabs", "items"]

  ## Collect interval.
  # 单位 "ns", "us" (or "µs"), "ms", "s", "m", "h"
  interval = "10s"

[inputs.memcached.tags]
  # some_tag = "some_value"
  # more_tag = "some_other_value"
  # ...

Once configured, restart DataKit.

The collector can now be turned on by ConfigMap Injection Collector Configuration.

Metric

For all the following data collections, a global tag named host is appended by default (the tag value is the host name of the DataKit), or other tags can be specified in the configuration by [inputs.memcached.tags]:

 [inputs.memcached.tags]
  # some_tag = "some_value"
  # more_tag = "some_other_value"
  # ...

memcached

  • tag
Tag Description
server The host name from which metrics are gathered
  • metric list
Metric Description Type Unit
accepting_conns Whether or not server is accepting conns int count
auth_cmds Number of authentication commands handled, success or failure int count
auth_errors Number of failed authentications int count
bytes Current number of bytes used to store items int B
bytes_read Total number of bytes read by this server from network int B
bytes_written Total number of bytes sent by this server to network int B
cas_badval Number of CAS for which a key was found, but the CAS value did not match int count
cas_hits Number of successful CAS requests int count
cas_misses Number of CAS requests against missing keys int count
cmd_flush Cumulative number of flush requests int count
cmd_get Cumulative number of retrieval requests int count
cmd_set Cumulative number of storage requests int count
cmd_touch Cumulative number of touch requests int count
conn_yields Number of times any connection yielded to another due to hitting the -R limit int count
connection_structures Number of connection structures allocated by the server int count
curr_connections Number of open connections int count
curr_items Current number of items stored int count
decr_hits Number of successful decr requests int count
decr_misses Number of decr requests against missing keys int count
delete_hits Number of deletion requests resulting in an item being removed int count
delete_misses umber of deletions requests for missing keys int count
evicted_unfetched Items evicted from LRU that were never touched by get/incr/append/etc int count
evictions Number of valid items removed from cache to free memory for new items int count
expired_unfetched Items pulled from LRU that were never touched by get/incr/append/etc before expiring int count
get_hits Number of keys that have been requested and found present int count
get_misses Number of items that have been requested and not found int count
hash_bytes Bytes currently used by hash tables int B
hash_is_expanding Indicates if the hash table is being grown to a new size int count
hash_power_level Current size multiplier for hash table int count
incr_hits Number of successful incr requests int count
incr_misses Number of incr requests against missing keys int count
limit_maxbytes Number of bytes this server is allowed to use for storage int B
listen_disabled_num Number of times server has stopped accepting new connections (maxconns) int count
reclaimed Number of times an entry was stored using memory from an expired entry int count
threads Number of worker threads requested int count
total_connections Total number of connections opened since the server started running int count
total_items Total number of items stored since the server started int count
touch_hits Number of keys that have been touched with a new expiration time int count
touch_misses Number of items that have been touched and not found int count
uptime Number of secs since the server started int count

memcached_items

  • tag
Tag Description
server The host name from which metrics are gathered
slab_id The id of the current slab
  • metric list
Metric Description Type Unit
age Age of the oldest item in the LRU int count
crawler_reclaimed Number of items which freed by the LRU Crawler int count
direct_reclaims Number of worker threads which had to directly pull LRU tails to find memory for a new item int count
evicted Number of the items which had to be evicted from the LRU before expiring int count
evicted_nonzero Number of the onzero items which had an explicit expire time set had to be evicted from the LRU before expiring int count
evicted_time Seconds since the last access for the most recent item evicted from this class int s
evicted_unfetched Number of the valid items evicted from the LRU which were never touched after being set int count
expired_unfetched Number of the expired items reclaimed from the LRU which were never touched after being set int count
lrutail_reflocked Number of items which found to be refcount locked in the LRU tail int count
moves_to_cold Number of items which were moved from HOT or WARM into COLD int count
moves_to_warm Number of items which were moved from COLD to WARM int count
moves_within_lru Number of active items which were bumped within HOT or WARM int count
number Number of items presently stored in this slab class int count
number_cold Number of items presently stored in the COLD LRU int count
number_hot Number of items presently stored in the HOT LRU int count
number_noexp Number of items presently stored in the NOEXP class int count
number_warm Number of items presently stored in the WARM LRU int count
outofmemory Number of the underlying slab class which was unable to store a new item int count
reclaimed Number of entries which were stored using memory from an expired entry int count
tailrepairs How many times memcache self-healed a slab with a refcount leak int count

memcached_slabs

  • tag
Tag Description
server The host name from which metrics are gathered
slab_id The id of the current slab
  • metric list
Metric Description Type Unit
active_slabs Total number of slab classes allocated int count
cas_badval Number of CAS commands failed to modify a value due to a bad CAS id int count
cas_hits Number of CAS commands modified this slab class int count
chunk_size The amount of space each chunk uses int B
chunks_per_page How many chunks exist within one page int count
cmd_set Number of set requests stored data in this slab class int count
decr_hits Number of decrs commands modified this slab class int count
delete_hits Number of delete commands succeeded in this slab class int count
free_chunks Chunks not yet allocated to items or freed via delete int count
free_chunks_end Number of free chunks at the end of the last allocated page int count
get_hits Number of get requests were serviced by this slab class int count
incr_hits Number of incrs commands modified this slab class int count
total_chunks Total number of chunks allocated to the slab class int count
total_malloced Total amount of memory allocated to slab pages int B
total_pages Total number of pages allocated to the slab class int count
touch_hits Number of touches serviced by this slab class int count
used_chunks How many chunks have been allocated to items int count

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