Deephaven Python Source

This folder contains Deephaven Community Core's Python source code, tests, and more. Source code can be found in server/deephaven and unit tests can be found in server/tests. Other content includes jpy, the Python client, wheels, and more.

Requirements

Development and contribution requires Python 3.8+. We recommend always staying up-to-date on the latest Python version.

Virtual environments

Deephaven Python development should always be done from a virtual environment. See PEP 405 for the motivation behind virtual environments (venvs). Creating and activating a venv takes two shell commands.

From the root directory of your deephaven-core clone:

python3 -m venv .venv # Create a venv. Only needed once.
source .venv/bin/activate # Activate the virtual environment.

A virtual environment only exists in the terminal it's run from. New or other terminal windows or tabs will need to activate the virtual environment again.

Once finished with a virtual environment, exiting is done with a single command.

deactivate # Exit the venv when finished

Local Development

Using a pip editable install is recommended so that Python changes are reflected when your server is restarted. These instructions are for the Python server package in py/server but should apply to any other Python packages.

Install the Python server package. This will install the dependencies as well as the autocomplete dependencies.

DEEPHAVEN_VERSION=0.dev pip install -e "py/server[autocomplete]"

After installing, a pip list should include deephaven-core with an editable project location listed.

Now you can start the Java server by following the instructions here. Any time you make Python changes, restart the server to apply them.

Local Build

You can use these instructions if you do not plan on making frequent changes to your local Python environment or need to try things in a more production-like environment locally.

First, run the following command to build the server and embedded-server if needed. The embedded-server is used to start pip-installed Deephaven.

./gradlew :py-server:assemble

# If using embedded-server
# You can run both tasks w/ ./gradlew :task1 :task2 if you need both
./gradlew :py-embedded-server:assemble

Then run the following commands to install the server package. Note that the wheel folder should only contain 1 file, so you should be able to tab-complete the wheel file.

Note: Adding the --no-deps flag on subsequent installs will skip re-installing other dependencies.

pip install --force py/server/build/wheel/deephaven_core-<version>-py3-none-any.whl

# If using embedded-server
# You can combine as pip install core.whl server.whl if you need both
pip install --force py/embedded-server/build/wheel/deephaven_server-<version>-py3-none-any.whl

If you make Python server code changes, you will need to re-build and re-install the wheel.

Start the Java server by following the instructions here.

Tests

Python unit tests must be run from the root directory of the cloned repository.

cd ..
./gradlew integrations:test-py-deephaven