large-class-init-style

name	large-class-init-style
description	`__init__` style for SGLang `Scheduler`, `TokenizerManager`, and `ModelRunner`. Use when modifying the `__init__` of any of these three classes, or reviewing changes that add new construction logic to them.

__init__ Style for Scheduler / TokenizerManager / ModelRunner

Apply when modifying the __init__ of:

• Scheduler — python/sglang/srt/managers/scheduler.py
• TokenizerManager — python/sglang/srt/managers/tokenizer_manager.py
• ModelRunner — python/sglang/srt/model_executor/model_runner.py

Why

• Downstream forks override one piece (tokenizer, KV cache, IPC, …).
• Inline logic forces them to copy the whole __init__, which rots against upstream.
• Splitting into init_* helpers lets them override exactly what they need.
• Reference shape: TokenizerManager.__init__ in python/sglang/srt/managers/tokenizer_manager.py.

Rules

• __init__ is an orchestrator. Sequence of self.init_*(...) calls + minimal glue. No non-trivial construction inlined.
• One helper per overridable unit. Each init_* = one concern a subclass might swap. Don't lump.
• Naming: init_<thing> (snake_case, names the component). Conditional construction → maybe_init_<thing>, gate inside the helper.
• No silent state coupling. A helper only reads self.* set by earlier helpers. Ordering lives in __init__. Shared intermediates → pass as args, not via self.*.
• New logic = new helper. Default to adding init_<thing>, not another inline block. One-line self.foo = server_args.foo is fine; structured logic is not.
• Preserve override points. Prefer additive changes to existing init_* signatures. Breaking changes → call out in PR.

Scope

Only the three classes listed above. Not other manager-style classes, not small dataclass/utility constructors.