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Author: josevalim

README.md

@@ -11,6 +11,20 @@ Pythonx runs a Python interpreter in the same OS process as your Elixir
 application, allowing you to evaluate Python code and conveniently
 convert between Python and Elixir data structures.
 
+The goal of this project is to better integrate Python workflows within
+Livebook and its usage in actual projects must be done with care due to
+Python's global interpreter lock (GIL), which prevents from multiple threads
+executing Python code at the same time. Consequently, calling `Pythonx`
+from multiple Elixir processes does not provide the concurrency you might
+expect and thus it can be a source of bottlenecks. However, this concerns
+regular Python code. Packages with CPU-intense functionality, such as `numpy`,
+have native implementation of many functions and invoking those releases the
+GIL. GIL is also released when waiting on I/O operations. In other words,
+if you are using this library to integrate with Python, make sure it happens
+in a single Elixir process or that its underlying libraries can deal with
+concurrent invocation. Otherwqise, prefer to use Elixir's `System.cmd/3` or
+`Port`s to manage multiple Python programs via I/O.
+
 ## Usage (script)
 
 Add Pythonx to your dependencies:

lib/pythonx/application.ex

@@ -20,14 +20,13 @@ defmodule Pythonx.Application do
 
   # If configured, Python and dependencies are fetched at compile time,
   # so we automatically initialize the interpreter on boot.
+  #
+  # TODO: My suggestion would be to call ut :pythonx, :uv_init, to make
+  # it clear it will start the runtime.
   if pyproject_toml = Application.compile_env(:pythonx, :uv)[:pyproject_toml] do
+    Pythonx.Uv.fetch(pyproject_toml, true)
     defp maybe_uv_init(), do: Pythonx.Uv.init(unquote(pyproject_toml), true)
   else
     defp maybe_uv_init(), do: :noop
   end
 end
-
-# If configured, fetch Python and dependencies when compiling.
-if pyproject_toml = Application.compile_env(:pythonx, :uv)[:pyproject_toml] do
-  Pythonx.Uv.fetch(pyproject_toml, true)
-end