[BugFix] Fix legacy logger propagation leaking unformatted logs to stderr

[gongweibao]

Motivation

Legacy loggers (legacy.*) created by get_trace_logger() and _get_legacy_logger() had propagate left as True (commented out since PR #3431). This caused all log levels (INFO/WARNING/ERROR) to propagate to the Python root logger, which outputs to stderr using the default LEVEL:name:message format — without timestamps.

Impact:

• stderr log files (*-stderr.log) are polluted with INFO-level logs that shouldn't be there
• ERROR logs in stderr have no timestamps, causing downstream tools (e.g. paddlerl diagnose) to display (no ts) and fail to filter events by time

Root cause: PR #3431 introduced the legacy.* namespace (logging.getLogger(f"legacy.{name}")) but kept logger.propagate = False commented out with the note "maintain original logic". The original code didn't need it because loggers were at the top level. After the namespace change, legacy.api_server became a child of the root logger, and propagation leaked all logs to stderr.

Modifications

• Uncomment logger.propagate = False in both get_trace_logger() and _get_legacy_logger()
• Update test assertion from assertTrue to assertFalse to match the fix

Usage or Command

No usage change. After this fix:

• stderr only contains ERROR-level logs from channel loggers (with proper %(asctime)s timestamps)
• INFO/WARNING logs from legacy loggers no longer leak to stderr

Accuracy Tests

N/A — logging-only change, no impact on model outputs.

Checklist

• Add at least a tag in the PR title.
• Format your code, run pre-commit before commit.
• Add unit tests. Test updated to match fix, 109 tests all passing.
• Provide accuracy results.
• 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.

[paddle-bot]

Thanks for your contribution!

[Copilot]

Pull request overview

该 PR 修复 get_trace_logger() / _get_legacy_logger() 创建的 legacy.* logger 默认向 root logger 传播，导致日志以 root logger 的默认格式泄漏到 stderr（缺少期望的格式/时间戳）的问题，使 legacy logger 的输出与 FastDeploy 的日志体系隔离。

Changes:

• 在 get_trace_logger() 与 _get_legacy_logger() 中显式设置 logger.propagate = False
• 更新单元测试断言，使其与新的传播行为一致

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
fastdeploy/logger/logger.py	禁用 legacy logger 向 root logger 的传播，避免 stderr 被未格式化日志污染
tests/logger/test_logger.py	更新 legacy logger 的 propagate 断言以匹配修复后的行为

Comments suppressed due to low confidence (1)

tests/logger/test_logger.py:88

• 本次同时修改了 get_trace_logger() 的 logger.propagate 行为（改为 False），但当前测试只覆盖了 _get_legacy_logger() 的 propagate。建议在 test_get_trace_logger_basic（或单独用例）里也断言 logger.propagate 为 False，避免后续回归。

        legacy_logger = self.logger._get_legacy_logger("test", "test.log")
        self.assertFalse(legacy_logger.propagate)

    def test_get_trace_logger_basic(self):
        """Test basic functionality of get_trace_logger"""
        logger = self.logger.get_trace_logger("test_trace", "trace_test.log")

[Copilot]

这里对 console_handler 设置 propagate 没有实际效果：propagate 是 logging.Logger 的属性，不是 logging.Handler 的属性。该行会让人误以为 handler 能控制传播，建议删除该行，统一由 logger.propagate = False 控制。

Suggested change

console_handler.propagate = False

[Copilot]

这里对 console_handler 设置 propagate 没有实际效果：propagate 是 logging.Logger 的属性，不是 logging.Handler 的属性。建议删除该行，避免误导，统一由 logger.propagate = False 控制。

Suggested change

console_handler.propagate = False

[PaddlePaddle-bot]

🤖 AI Code Review | 2026-04-24 21:37:03

📋 Review 摘要

PR 概述：修复 legacy.* 命名空间下的 logger 因 propagate=True 导致日志泄漏到 stderr 的问题。
变更范围：fastdeploy/logger/logger.py、tests/logger/test_logger.py
影响面 Tag：BugFix

问题

级别	文件	概述
🟡 建议	tests/logger/test_logger.py:84	get_trace_logger() 同样被修复，但缺少对应的 propagate=False 测试断言

总体评价

修复思路正确，根因分析清晰，PR 描述详尽。仅建议在测试中补充 get_trace_logger() 的 propagate 断言，保持两处修复的测试覆盖对称。

[PaddlePaddle-bot]

🟡 建议 get_trace_logger() 缺少 propagate 测试覆盖

本次 PR 同时修复了 get_trace_logger() 和 _get_legacy_logger() 中的 propagate 设置，但测试用例 test_logger_propagate 仅验证了 _get_legacy_logger() 的行为，get_trace_logger() 缺少对应断言。

建议补充：

def test_logger_propagate(self):
    """Test log propagation settings"""
    legacy_logger = self.logger._get_legacy_logger("test", "test.log")
    self.assertFalse(legacy_logger.propagate)
    # Also verify get_trace_logger
    trace_logger = self.logger.get_trace_logger("test_trace", "test_trace.log")
    self.assertFalse(trace_logger.propagate)

[codecov-commenter]

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