large-class-style

Code Style for Scheduler / TokenizerManager / ModelRunner

Conventions for SGLang's three large classes:

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

1. Frozen Code

• Some core files are frozen: orchestration-only — a thin composition root that constructs collaborators, wires them, delegates to them, and coordinates the calls. They must stay that way.
• Domain logic does not belong in a frozen file; it lives in a collaborator class in its own module.

1.1 Why

• The file is a thin orchestrator over collaborator classes; freezing keeps it that way and stops it growing back into a god class.
• Keeping domain logic in collaborators (their own files) is what makes per-file code ownership, single responsibility, and unit testing possible.
• The orchestrator is the composition root: it may know about every collaborator, because wiring and sequencing them is its job. Coordination stays here — domain logic does not.

1.2 Frozen files

• python/sglang/srt/model_executor/model_runner.py

1.3 Allowed: orchestration

Every statement refers to a collaborator and is one of:

1. Construct — a short init_<thing> helper whose body is essentially a single construction (follows §2); use maybe_init_<thing> with a one-line gate when conditional.
2. Wire — a short call that runs the helper from the orchestrator (e.g. in __init__).
3. Delegate — calls to a collaborator's methods at the necessary call sites (self.foo.run(...)).
4. Coordinate — the minimal control flow that selects or orders the above: an if choosing whether / which collaborator to wire or call, the order of calls, threading one call's result into the next.

• Heuristic: a statement is allowed only if it constructs, wires, delegates, or selects/orders those — never if it computes or transforms a value beyond passing arguments and results through.