Hi all,
At its last meeting the jank task force discussed improving
responsiveness of the spellchecker but we didn't come to a solid
conclusion so I thought I'd bring it up here to see if anyone else has
opinions. The main concern is that we don't block the IO thread on
file access. To this end, I recently moved initialization of the
spellchecker from the IO thread to the file thread. However, instead
of reading in the spellchecker dictionary in one solid chunk, we
memory-map it. Then later we check individual words on the IO thread,
which will be slow since the dictionary starts off effectively
completely paged out. The proposal is that we read in the dictionary
at spellchecker intialization instead of memory mapping it.
Memory mapping pros:
- possibly uses less overall memory, depending on the structure of the
dictionary and the usage pattern of the user.
- <strike>loading the dictionary doesn't block for a long
time</strike> this one no longer occurs either way due to my recent
refactoring
Reading it all at once pros:
- costly disk accesses are kept to the file thread (excepting future
memory paging)
- overall disk access time is probably lower (since we can read in the
dict in one chunk)
For reference, the English dictionary is about 500K, and most
dictionaries are under 2 megs, some (such as Hungarian) are much
higher, but no dictionary is over 10 megs.
Opinions?
-- Evan Stade
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