watchdog reloader uses excessive CPU

[raylu]

the watchdog reloader calls run_step every second by default

werkzeug/src/werkzeug/_reloader.py

Line 381 in 504a8c4

self.run_step()

on our project with 13,000 files, this causes os.path.isfile to take 15% of a CPU core

I ran py-spy record --pid ... --output profile.speedscope.json --format speedscope for about 8 seconds on an idle app. you can place profile.speedscope.json into https://www.speedscope.app/ and see 8 calls to run() which take about 150ms each:

increasing ReloaderLoop.interval helps a lot, but means reloads have to wait for the next iteration

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Environment:

• Python version: 3.12.7
• Werkzeug version: 3.0.6