This fixes two issues:
* The syntax check logic we had for zerver.tornado.autoreload would
end up clearing _reload_hooks if one of the files that had changed
was zerver.tornado.autoreload itself (because we'd had re-imported
the current module), which could be incredibly confusing when trying
to test the autoreload logic. It seems better to just not run the
syntax check for syntax errors in this file.
Similarly, because reloading event_queue.py would destroy the state
in the queues, we avoid that as well.
* We make sure to flush stdout after running and reload hooks, to make
sure their output reaches the user.
We've for a long time been plagued by run-dev.py needing to be
restarted every time one does a rebase that has merge conflicts,
because the Tornado process restarts itself into a syntax error and
crashes.
This fixes the Tornado autoreload process to check explicitly for
whether files actually syntax-check before trying to actually reload
the Tornado process to run that code.
There are a few things that are a bit janky:
* Ideally, this would go into Tornado upstream
* We removed the `_watched_files` feature, which we weren't using.
* Ideally, we'd use something other than `importlib.reload` that just
does the syntax-check without adjusting the state within our current
process.
Fixes#4351.
Tim Abbott
Anders Kaseorg
Vishnu Ks