stats — Server Metrics & Slabs

Code

stats
# STAT pid 1234
# STAT uptime 3600
# STAT curr_connections 12
# STAT total_connections 123
# STAT get_hits 9821
# STAT get_misses 179
# STAT curr_items 1024
# STAT bytes 5242880
# STAT evictions 3
# STAT limit_maxbytes 67108864
# END

# Hit rate = get_hits / (get_hits + get_misses)

stats items
# STAT items:1:number 100    <- slab 1 has 100 items
# STAT items:5:number 50     <- slab 5 has 50 items

stats slabs
# STAT 1:chunk_size 96
# STAT 1:total_chunks 10922
# STAT 5:chunk_size 232

stats sizes            # deprecated; may be slow
stats cachedump 5 100  # dump up to 100 keys from slab 5 (debug only)
stats reset            # reset counters (NOT data)

Explanation

stats gives a snapshot of the server: get_hits/get_misses for hit rate, evictions for memory pressure, curr_items/bytes for usage, limit_maxbytes for the cap. stats items breaks down items per slab class (Memcached uses fixed-size chunk allocator: each class serves a size bucket). stats slabs shows chunk sizes and free chunks per class. Use cachedump to enumerate keys in a slab for debugging (it's not exhaustive and is slow — don't use it in production hot paths). Watch evictions and bytes — if evictions is rising, you're over capacity and need more memory or shorter TTLs.

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