Frequently Asked Questions (FAQ)

This is a list of frequently asked questions about Tarantella. Please feel free to suggest new ones!


How can I ssh to localhost without password?

In order to run Tarantella programs, you will need to be able to ssh to localhost without password. In order to do that generate ssh keys first:

cd ~/.ssh

Make sure not to overwrite existing keys. When asked for a passphrase, Enter passphrase (empty for no passphrase):, simply leave empty and return with enter. Also take specific care to set correct user rights on all files in .ssh, cf. for instance here. Next, append the public key to the authorized_keys file:

cat >> authorized_keys

Now, install and start an ssh server, e.g., openssh-server on Fedora. More details can be found for instance here.


I get an execution error GPI library initialization incorrect environment vars when trying to run my script. What shall I do?

Most likely you are running your program with python or ./ Please make sure to execute your code with tarantella -- instead.


I get an execution error GPI library initialization general error. What shall I do?

This error occurs when the GPI-2 library tries to connect to a previously used socket, which is not yet released. Try to re-run your code after a short while so that the port becomes available again.


The execution seems to stall. What shall I do?

Please use the tarantella --cleanup command to kill any processes that might be still running from a previous (aborted) call to tarantella as shown here. Note that you can also interrupt a running tarantella instance (distributed on multiple nodes) by using Ctrl+c.


When trying to build Tarantella, CMake cannot find pybind11:
Could not find a package configuration file provided by "pybind11" with any
of the following names: [...]
What shall I do?

This error occurs when pybind11 is installed using pip. Please use conda instead, as recommended in the installation guide.


When trying to build Tarantella, CMake does not detect the Python interpreter from the active conda environment. What shall I do?

You will need to manually add the path to the conda environment’s bin directory to your PATH. You will also need to specify the path to the python library on the command line when configuring Tarantella:

export PATH=${PATH_TO_CONDA_ENV}/bin:${PATH}


Why do I get runtime errors when I compile Tarantella using clang?

Currently, Tarantella can be built properly only by using gcc.

The clang compiler relies on a different standard library (libc++ instead of libstdc++ that is used by gcc).

However, the TensorFlow pip/conda packages for Linux are compiled using gcc. The tnt_tfops library in Tarantella is linked against Tensorflow, which leads to linking errors at runtime if the two libraries expect a different standard library implementation.


I get undefined symbol errors in the library at runtime. What can I do?

Such errors might be due to a TensorFlow version mismatch between Tarantella and the loaded Conda environment. Make sure to use the same Conda environment that was active when compiling Tarantella.


Why does loading a Tarantella or Keras model from YAML fail?

Make sure to have the PyYAML Python package installed in your environment, using version 3.13 or below. Newer versions of PyYAML do not work with TensorFlow model loading.

pip install PyYAML==3.13


Can I install Tarantella on MacOS?

Tarantella is only supported on Linux systems, as its GPI-2 dependency is built on top of a Linux kernel API called epoll.