[Cherry-Pick][BugFix] Fix misleading logging in worker_process for request counting (#5939)

[Copilot]

Motivation

Cherry-pick PR #5939 from develop to release/2.4 branch. The original logging misrepresented metrics: num_running_requests printed the batch slot index (not request count), and num_insert_requests included DECODE requests (not just new inserts).

Modifications

Variable renaming and cleanup:

• num_running_requests → max_occupied_batch_index (3 locations: initialization, assignment, function calls)
• Removed unused req_ids variable initialization

Accurate request counting:

• Import RequestType to distinguish PREFILL vs DECODE requests
• Add num_prefill_requests: count of PREFILL requests in current batch
• Add num_scheduled_requests: total requests scheduled in batch
• Rename req_ids → scheduled_request_ids for clarity

Updated log output:

Before:

logger.info(
    f"Rank: {self.local_rank}, num_running_requests: {num_running_requests}, "
    f"num_insert_requests: {len(req_dicts)}, req_ids: {req_ids}"
)

After:

logger.info(
    f"Rank: {self.local_rank}, num_prefill_requests: {num_prefill_requests}, "
    f"max_occupied_batch_index: {max_occupied_batch_index}, "
    f"num_scheduled_requests: {num_scheduled_requests}, "
    f"scheduled_request_ids: {scheduled_request_ids}"
)

Usage or Command

No usage changes. Logging output now accurately reflects request metrics for debugging and monitoring.

Accuracy Tests

N/A - logging change only, no model output affected.

Checklist

• Add at least a tag in the PR title.
• Format your code, run pre-commit before commit.
• Add unit tests. Reason: Logging output change only. Original PR validated with mock requests covering all scenarios.
• Provide accuracy results. Reason: N/A - logging change only.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

Original prompt

#5939 这个PR的改动cherry pick进release/2.4分支

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[Jiang-Jia-Jun]

@copilot Your PR code style check failed.
Please install pre-commit locally and set up git hook scripts:

pip install pre-commit==4.2.0
pre-commit install

Then, run pre-commit to check codestyle issues in your PR:

pre-commit run --files fastdeploy/worker/worker_process.py

[Copilot]

@copilot Your PR code style check failed.
Please install pre-commit locally and set up git hook scripts:

...

Fixed in commit 782b4f3. Removed the unused req_ids variable that was causing the flake8 failure. All pre-commit checks now pass.