Fix the program hang caused by duplicate serialization

[hhaAndroid]

No description provided.

[hhaAndroid]

@claude approve

[claude]

LGTM. The fix correctly deduplicates Ray object serialization by using explicit ray.put() with a data_batch_refs cache keyed by dp_idx. Previously, each worker in the same data-parallel group would implicitly serialize the same data slice via .remote(), causing redundant serialization that could lead to hangs. The cleanup with del data_batch_refs in the finally block is also appropriate.

[claude]

Claude: Approved PR #1949 as requested.

What was requested: Approve the PR.

Actions taken: Reviewed the diff and approved with comments. The fix correctly addresses a program hang caused by duplicate Ray object serialization — workers in the same data-parallel group now share a single ray.put() object ref instead of each implicitly serializing the same data slice via .remote().