Sharing Python Objects with Vineyard#

As discussed in Objects, each object in Vineyard consists of two parts:

  1. The data payload, which is stored locally in the corresponding Vineyard instance

  2. The hierarchical metadata, which is shared across the entire Vineyard cluster

Specifically, a Blob represents the unit where the data payload resides within a Vineyard instance. A blob object holds a segment of memory in the bulk store of the Vineyard instance, allowing users to save their local buffer into a blob and later retrieve the blob in another process using a zero-copy approach through memory mapping.

>>> payload = b"Hello, World!"
>>> blob_id = client.put(payload)
>>> blob = client.get_object(blob_id)
>>> print(blob.typename, blob.size, blob)

vineyard::Blob 28 Object <"o800000011cfa7040": vineyard::Blob>

On the other hand, the hierarchical metadata of Vineyard objects is shared across the entire cluster. In the following example, for the sake of simplicity, we launch a Vineyard cluster consisting of two Vineyard instances on the same machine. However, in real-world scenarios, these Vineyard instances would be distributed across multiple machines within the cluster.

$ python3 -m vineyard --socket /var/run/vineyard.sock1
$ python3 -m vineyard --socket /var/run/vineyard.sock2

With this setup, we can create a distributed pair of arrays in Vineyard, where the first array is stored in the first Vineyard instance listening to the IPC socket /var/run/vineyard.sock1, and the second array is stored in the second instance listening to the IPC socket /var/run/vineyard.sock2.

>>> import numpy as np
>>> import vineyard
>>> import vineyard.data.tensor

>>> # build the first array in the first vineyard instance
>>> client1 = vineyard.connect('/var/run/vineyard.sock1')
>>> id1 = client1.put(np.zeros(8))
>>> # persist the object to make it visible to form the global object
>>> client1.persist(id1)

>>> # build the second array in the second vineyard instance
>>> client2 = vineyard.connect('/var/run/vineyard.sock2')
>>> id2 = client2.put(np.ones(4))
>>> # persist the object to make it visible to form the global object
>>> client2.persist(id2)

>>> # build the pair from client1
>>> obj1 = client1.get_object(id1)
>>> obj2 = client2.get_object(id2)
>>> id_pair = client1.put((obj1, obj2))

>>> # get the pair object from client2
>>> obj_pair = client2.get_object(id_pair)
>>> print(obj_pair.first.typename, obj_pair.first.size(), obj_pair.second.size())

vineyard::Array 8 4

>>> # get the pair value from client2
>>> value_pair = client2.get(id_pair)
>>> print(value_pair)

(None, [1, 1, 1, 1])

In this example, we can access the metadata of the pair object from client2 even though it was created by client1. However, we cannot retrieve the payload of the first element of the pair from client2 because it is stored locally in the first Vineyard instance.