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box.slab.stats() | Tarantool
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box.slab.stats()

box.slab.stats()

box.slab.stats()

Show a detailed memory usage report (in bytes) for the slab allocator. The report is broken down into groups by data item size as well as by slab size (64-byte, 136-byte, etc). The report includes the memory allocated for storing both tuples and indexes.

return:
  • mem_free is the allocated, but currently unused memory;
  • mem_used is the memory used for storing data items (tuples and indexes);
  • item_count is the number of stored items;
  • item_size is the size of each data item;
  • slab_count is the number of slabs allocated;
  • slab_size is the size of each allocated slab.
rtype:

table

Example:

Here is a sample report for the first group:

tarantool> box.slab.stats()[1]
---
- mem_free: 16232
  mem_used: 48
  item_count: 2
  item_size: 24
  slab_count: 1
  slab_size: 16384
...

This report is saying that there are 2 data items (item_count = 2) stored in one (slab_count = 1) 24-byte slab (item_size = 24), so mem_used = 2 * 24 = 48 bytes. Also, slab_size is 16384 bytes, of which 16384 - 48 = 16232 bytes are free (mem_free).

A complete report would show memory usage statistics for all groups:

tarantool> box.slab.stats()
---
- - mem_free: 16232
    mem_used: 48
    item_count: 2
    item_size: 24
    slab_count: 1
    slab_size: 16384
  - mem_free: 15720
    mem_used: 560
    item_count: 14
    item_size: 40
    slab_count: 1
    slab_size: 16384
  <...>
  - mem_free: 32472
    mem_used: 192
    item_count: 1
    item_size: 192
    slab_count: 1
    slab_size: 32768
  - mem_free: 1097624
    mem_used: 999424
    item_count: 61
    item_size: 16384
    slab_count: 1
    slab_size: 2097152
  ...

The total mem_used for all groups in this report equals arena_used in box.slab.info() report.