Speed up processing of new files in daemon by caching ASTs #10128
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ilevkivskyi
approved these changes
Feb 22, 2021
mypy/build.py
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| manager = self.manager | ||
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| # Can we reuse a previously parsed AST? This avoids redundant work in daemon. | ||
| cached = self.id in manager.ast_cache and True |
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Why do you need and True? Leftover from debugging?
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Yeah, I'll remove it.
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Processing newly installed stub files, in particular, could be quite slow incrementally
in mypy daemon. This is because adding N files results in N steps interally, each of
which adds one file. However, each step parses all remaining files, resulting in
an O(n**2) algorithm.
For example, processing
sixstubs could take about 40s (when not using acompiled mypy).
Partially address the issue by caching parsed ASTs during a single increment.
This speeds up the
import sixuse case by about 3x when not using a compiledmypy. It's still about 3x slower when using daemon, however.