refactor: replace print() calls with structured logging in verl daemon by Alexi5000 · Pull Request #530 · microsoft/agent-lightning

Alexi5000 · 2026-05-21T22:06:56Z

Summary

Add import logging and module-level logger to agentlightning/verl/daemon.py
Replace 18 bare print() calls with structured logger calls at appropriate levels
Preserve print(..., file=f) calls that write diagnostic logs to files (intentional I/O)

Motivation

The verl daemon module uses bare print() for all runtime messages — server startup, task progress, data validation warnings, and error reporting. This makes it impossible to filter, format, or route these messages through the logging infrastructure already configured in agentlightning/logging.py.

Log level mapping

Category	Level	Examples
Server lifecycle	`info`	Proxy/server started, all tasks finished
Task progress	`info`	Completed N/M tasks
Data validation	`warning`	Missing triplets, unknown rollout IDs, null rewards
Errors	`error`	Setup failures, timeout errors
Verbose proxy	`debug`	Individual request proxying

Test plan

Existing tests pass — no behavior change beyond output destination
Log messages appear in configured log handlers instead of bare stdout
print(..., file=f) diagnostic logs still write to files correctly

Replace 18 bare `print()` calls in `agentlightning/verl/daemon.py` with proper `logging` module calls at appropriate levels: - `logger.info()` for operational messages (server started, tasks complete) - `logger.warning()` for data validation issues (missing triplets, unknown IDs) - `logger.error()` for failures (setup errors, timeout errors) - `logger.debug()` for verbose proxy request logging This enables log filtering, formatting, and integration with the existing logging infrastructure configured in `agentlightning/logging.py`. Print-to-file calls (diagnostic mismatch logs) are left unchanged.

microsoft-github-policy-service · 2026-05-21T22:07:10Z

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Copilot

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR replaces direct print() statements with structured logging to improve observability and control over output verbosity.

Changes:

Introduced a module-level logger and switched various status/warning/error messages from print() to logger.*.
Updated proxy request logging to use parameterized logging instead of string interpolation.
Standardized runtime progress/status output (server startup, task completion) via logger.info/warning/error.

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            current_time = time.time()
            num_requests += 1
            if current_time - last_request_time > 60 or num_requests == 1 or num_requests % 100 == 0:
-                print(f"Proxying {request.method} request to {target_server}. Request data: {request.get_data()}")
+                logger.debug("Proxying %s request to %s. Request data: %s", request.method, target_server, request.get_data())
            last_request_time = current_time


        try:
            future.result(timeout=300)  # Wait for completion with a timeout
        except Exception as e:
-            print(f"Failed to set up data on server: {e}")
+            logger.error("Failed to set up data on server: %s", e)
            raise


            future.result()  # Wait indefinitely for all tasks to complete
        except Exception as e:
-            print(f"Error while waiting for tasks to finish: {e}")
+            logger.error("Error while waiting for tasks to finish: %s", e)


Copilot AI review requested due to automatic review settings May 21, 2026 22:06

Copilot AI reviewed May 21, 2026

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refactor: replace print() calls with structured logging in verl daemon#530

refactor: replace print() calls with structured logging in verl daemon#530
Alexi5000 wants to merge 1 commit into
microsoft:mainfrom
Alexi5000:pr/replace-debug-prints-with-logging

Alexi5000 commented May 21, 2026

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Alexi5000 commented May 21, 2026

Summary

Motivation

Log level mapping

Test plan

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microsoft-github-policy-service Bot commented May 21, 2026

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Pull request overview

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