1926662 - Instrument nsTArray to help with optimization

Status: NEW

(Core :: XPCOM, enhancement)

Description

[Randell Jesup [:jesup] (needinfo me)]

We should consider modifying nsTArray to record in a hashtable keyed by file/line# containing:
a) how many are created,
b) how many exist at once (optional),
c) max size distribution (or at least average size) (note, not destruction size)

Then dump the hashtable at shutdown.
This can be used for finding 'hot' nsTArrays, and also good sizes for AutoTArrays or initial array sizes/SetCapacity to reduce allocation traffic.

This could be optionally compiled in as needed once in a while to run a check. (#ifdef TARRAY_STATS)