The relevant diff of releases is: release_2.22.0.dev3...release_2.22.0a0

Looks like #20946 introduced this line, after turning some other logs down.

I've also wondered, why does the same log message appear twice? Do we initialize twice?

I'm not sure yet.

Initial investigation:

Extra factor, with pantsd (i.e. no --no-pantsd flag) it only appears once:

cd $(mktemp -d)
touch pants.toml

echo "First"
PANTS_VERSION=2.22.0 pants version

echo
echo "Second"
PANTS_VERSION=2.22.0 pants version

First
09:12:21.26 [INFO] Initializing scheduler...
09:12:21.28 [INFO] Initializing Nailgun pool for 16 processes...
09:12:21.43 [INFO] Scheduler initialized.
2.22.0

Second
2.22.0

There's a few layers of functions from NailgunPool::new to EngineInitializer.setup_graph that are only called in one place (and not in a loop, AFAICT):

Finally, EngineInitializer.setup_graph is called in three places:

1. create_bootstrap_scheduler:

   pants/src/python/pants/init/options_initializer.py

   Line 118 in db9cf59

   EngineInitializer.setup_graph(

2. PantsDaemonCore._initialize:

   pants/src/python/pants/pantsd/pants_daemon_core.py

   Line 106 in db9cf59

   self._scheduler = EngineInitializer.setup_graph(

3. LocalPantsRunner.create:

   pants/src/python/pants/bin/local_pants_runner.py

   Line 123 in db9cf59

   scheduler = EngineInitializer.setup_graph(

Thus, for why things happen twice, the surface level is that the scheduler is initialised/graph is set-up for both bootstrapping (call site 1 is eventually also called in or before LocalPantsRunner.create too) and for "real" (call sites 2 and 3).

For why Pantsd behaves differently... my current hypothesises are:

1. turning off pantsd goes down an extra codepath??
2. initialising pantsd still does this twice, but the log line from one of them is hidden??