[Core] Setting RAY_DEFAULT_OBJECT_STORE_MEMORY_PROPORTION doesn't work?

[robertnishihara]

What happened + What you expected to happen

I'm setting RAY_DEFAULT_OBJECT_STORE_MEMORY_PROPORTION, but it seems like the actual object store memory doesn't change.

Versions / Dependencies

ray==2.48.0
MacOS
Python 3.11.4

Reproduction script

With variable set to 0.1

Starting IPython with RAY_DEFAULT_OBJECT_STORE_MEMORY_PROPORTION=0.1 ipython

In [1]: import ray

In [2]: ray._private.ray_constants.DEFAULT_OBJECT_STORE_MEMORY_PROPORTION
Out[2]: 0.1

In [3]: ray.init()
2025-08-05 10:36:23,992	INFO worker.py:1918 -- Started a local Ray instance. View the dashboard at http://127.0.0.1:8265 
Out[3]: RayContext(dashboard_url='127.0.0.1:8265', python_version='3.11.4', ray_version='2.48.0', ray_commit='03491225d59a1ffde99c3628969ccf456be13efd')

In [4]: ray.cluster_resources().get("object_store_memory", 0)
Out[4]: 2147483648.0

Then in a separate window, running ps aux | grep object_store_memory finds --object_store_memory=2147483648.

With variable set to 0.9

Starting IPython with RAY_DEFAULT_OBJECT_STORE_MEMORY_PROPORTION=0.9 ipython

In [1]: import ray

In [2]: ray._private.ray_constants.DEFAULT_OBJECT_STORE_MEMORY_PROPORTION
Out[2]: 0.9

In [3]: ray.init()
2025-08-05 10:41:52,874	INFO worker.py:1918 -- Started a local Ray instance. View the dashboard at http://127.0.0.1:8265 
Out[3]: RayContext(dashboard_url='127.0.0.1:8265', python_version='3.11.4', ray_version='2.48.0', ray_commit='03491225d59a1ffde99c3628969ccf456be13efd')

In [4]: ray.cluster_resources().get("object_store_memory", 0)
Out[4]: 2147483648.0

Somehow it seems like RAY_DEFAULT_OBJECT_STORE_MEMORY_PROPORTION is not taking effect.

Issue Severity

None

[robertnishihara]

It's possible that the above behavior is specific to MacOS.

Note that setting it via ray start --head --object-store-memory=1000000000 works.

[edoakes]

@robertnishihara looks like we cap object store memory to ~2GiB on mac:

ray/python/ray/_private/ray_constants.py

Line 123 in 7834d12

MAC_DEGRADED_PERF_MMAP_SIZE_LIMIT = (2) * (2**30)

[edoakes]

Working as intended on Mac, see previous discussion: #20388