Does pystan3 supports custom build/compile locations for its model cache

SaraAliza · June 25, 2024, 9:16pm

I am getting a read-only error when running pystan3 build() in a UDF.
I think the issue is related to the location that the code is being run from, which is read-only. I am looking to set a custom cache location to be set. Anyone can help?

ahartikainen · June 26, 2024, 6:58pm

Hi,

httpstan (which does the caching) uses appdirs

github.com

stan-dev/httpstan/blob/09c0cf229fd3276babe262355155b95ed02d336f/httpstan/cache.py#L18


      
          from importlib.machinery import EXTENSION_SUFFIXES
          from pathlib import Path
          
          import appdirs
          
          import httpstan
          
          logger = logging.getLogger("httpstan")
          
          
          def cache_directory() -> Path:
              """Get httpstan cache path."""
              return Path(appdirs.user_cache_dir("httpstan", version=httpstan.__version__))
          
          
          def model_directory(model_name: str) -> Path:
              """Get the path to a model's directory. Directory may not exist."""
              model_id = model_name.split("/")[1]
              return cache_directory() / "models" / model_id

Then you can follow appdirs user_cache_dir logic.

github.com

ActiveState/appdirs/blob/8734277956c1df3b85385e6b308e954910533884/appdirs.py#L264


      
                          appname = os.path.join(appname, version)
                      pathlist = [os.sep.join([x, appname]) for x in pathlist]
          
                  if multipath:
                      path = os.pathsep.join(pathlist)
                  else:
                      path = pathlist[0]
              return path
          
          
          def user_cache_dir(appname=None, appauthor=None, version=None, opinion=True):
              r"""Return full path to the user-specific cache dir for this application.
          
                  "appname" is the name of application.
                      If None, just the system directory is returned.
                  "appauthor" (only used on Windows) is the name of the
                      appauthor or distributing body for this application. Typically
                      it is the owning company name. This falls back to appname. You may
                      pass False to disable it.
                  "version" is an optional version path element to append to the
                      path. You might want to use this if you want multiple versions

Are you running on Linux or something else?

SaraAliza · June 26, 2024, 10:19pm

Thank you for the respond.
Yes I am running on Linux.
I followed your suggestion and was able to change the cache_directory by setting
os.environ[“XDG_CACHE_HOME”] = “/tmp/httpstan-cache”.

My question is if it is possible to write the model cache to another file system. We are using databricks clusters and by using UDF, it tries to write the model cache on the worker node directory which we dont have write access, I am trying to set this cache model directory to a DBFS, is there any functionality for that?
I see Path().mkdir() is used in httpstan.models.build_services_extension_module.

ahartikainen · June 27, 2024, 9:45am

Can you compile your models before calling UDF?

SaraAliza · June 27, 2024, 2:16pm

Yes, without UDF it works fine.

ahartikainen · June 29, 2024, 9:16pm

So maybe try to compile first with some global directory, then on each node either use this directory as a ref or copy them to local space?

I assume you have a wrapping function that does call pystan, so this config could be done there?

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Does pystan3 supports custom build/compile locations for its model cache

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