slow dmypy recheck times

Hi, I'm creating an issue for a problem discussed with @ilevkivskyi over at https://github.com/dropbox/mypy-PyCharm-plugin/issues/26

Ivan indicated that he's getting 300-500ms response time from dmypy on rechecks of a large code base, but on my moderately large code base, dmypy is taking over 15s to rerun if I edit any files.

I'm using 0.701.

First I start the daemon:

$ dmypy run -v -- python/packages
err                     : 
out                     : python/packages/filesize.py:51: error: I ...
platform                :     darwin
python_version          :        2_7
roundtrip_time          :     20.145
stats                   : {
'validate_meta_time': 0.005048990249633789,
'files_parsed': 819, 
'modules_parsed': 520, 
'stubs_parsed': 299, 
'parse_time': 4.495372295379639, 
'find_module_time': 0.3217315673828125, 
'find_module_calls': 5739, 
'graph_size': 819, 
'stubs_found': 299, 
'graph_load_time': 5.5668110847473145, 
'fm_cache_size': 1936, 
'sccs_left': 0, 
'nodes_left': 0, 
'cache_commit_time': 4.0531158447265625e-06, 
'load_fg_deps_time': 9.5367431640625e-07
}
status                  :          1

Then I edit a file and recheck:

$ dmypy recheck -v --update python/packages/foo.py
err                     : 
out                     : python/packages/foo.py:1 ...
platform                :     darwin
python_version          :        2_7
roundtrip_time          :     17.837
stats                   : {
'load_fg_deps_time': 2.5272369384765625e-05, 
'validate_meta_time': 1.3113021850585938e-05, 
'files_parsed': 1, 
'modules_parsed': 1, 
'stubs_parsed': 0, 
'parse_time': 0.002131938934326172, 
'find_module_time': 0.005670785903930664, 
'find_module_calls': 4, 
'semanal_time': 0.0036809444427490234,
'typecheck_time': 0.0034759044647216797, 
'deps_time': 0.001669168472290039, 
'finish_passes_time': 0.0005908012390136719, 
'update_isolated_time': 0.021294116973876953, 
'propagate_time': 0.003412961959838867, 
'find_changes_time': 0.0008490085601806641, 
'fg_update_time': 17.824305057525635,
'files_changed': 1
}
status                  :          1

Clearly the problem lies in fg_update_time!

It may be important to note that this code produces hundreds of errors. I'm using a custom mypy runner to filter out errors I'm not concerned with until my message filtering PR gets some traction.

Here's my mypy.ini:

[mypy]
python_version = 2.7
ignore_missing_imports = true
follow_imports = skip
warn_no_return = false
no_implicit_optional = true
warn_redundant_casts = true
warn_unused_ignores = true

Any guidance is greatly appreciated!

提供された mypy.ini の設定と比較可能なコードベースを使用して、dmypy run と dmypy recheck -v --update で報告された時間を再現します。まず fg_update_time 統計を追跡し、次に他の recheck の時間と比較して、その変更によって型チェックの結果を変えずに報告された遅延が短縮されることを確認します。