[Core] Enable command line logging for LLMEngine

[zhuohan123]

Summary: Enable command line logging for LLMEngine

Test Plan: All existing tests should pass

Differential Revision: D83118697

[facebook-github-bot]

@zhuohan123 has exported this pull request. If you are a Meta employee, you can view the originating diff in D83118697.

[gemini-code-assist]

Code Review

This pull request enables command-line logging for the LLMEngine by introducing a StatLoggerManager and periodic logging logic. The changes are a good step towards better observability. My review focuses on improving the initialization of state related to logging to enhance code clarity and maintainability. Specifically, I've suggested moving the initialization of _last_log_time to the __init__ method to centralize attribute setup and make the code easier to reason about.

[gemini-code-assist]

For better code clarity and to ensure all instance attributes are initialized in one place, it's recommended to initialize _last_log_time here within the if self.log_stats: block. This avoids lazy initialization in the do_log_stats_with_interval method, makes the class's attributes more explicit, and improves overall maintainability.

Suggested change

	self.logger_manager: Optional[StatLoggerManager] = None
	if self.log_stats:
	self.logger_manager = StatLoggerManager(
	vllm_config=vllm_config,
	custom_stat_loggers=stat_loggers,
	enable_default_loggers=log_stats,
	)
	self.logger_manager.log_engine_initialized()
	self.logger_manager: Optional[StatLoggerManager] = None
	if self.log_stats:
	self.logger_manager = StatLoggerManager(
	vllm_config=vllm_config,
	custom_stat_loggers=stat_loggers,
	enable_default_loggers=log_stats,
	)
	self.logger_manager.log_engine_initialized()
	self._last_log_time = time.time()

[gemini-code-assist]

With _last_log_time being initialized in __init__, this lazy initialization check becomes redundant. Removing it simplifies the do_log_stats_with_interval method, making it cleaner and more straightforward.

Suggested change

	def do_log_stats_with_interval(self) -> None:
	"""Log stats when the time interval has passed."""
	now = time.time()
	if not hasattr(self, "_last_log_time"):
	self._last_log_time = now
	if now - self._last_log_time >= envs.VLLM_LOG_STATS_INTERVAL:
	self.do_log_stats()
	self._last_log_time = now
	def do_log_stats_with_interval(self) -> None:
	"""Log stats when the time interval has passed."""
	now = time.time()
	if now - self._last_log_time >= envs.VLLM_LOG_STATS_INTERVAL:
	self.do_log_stats()
	self._last_log_time = now

[facebook-github-bot]

@zhuohan123 has exported this pull request. If you are a Meta employee, you can view the originating diff in D83118697.

[facebook-github-bot]

@zhuohan123 has exported this pull request. If you are a Meta employee, you can view the originating diff in D83118697.

[facebook-github-bot]

@zhuohan123 has exported this pull request. If you are a Meta employee, you can view the originating diff in D83118697.

[facebook-github-bot]

@zhuohan123 has exported this pull request. If you are a Meta employee, you can view the originating diff in D83118697.

[aarnphm]

LGTM