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.

Returns

none

• 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.

Return type

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 /reference/reference_lua/box_slab/slab_info report.