sgl-project/sglang · error · TimeoutError

Timeout while waiting for event '{name}'

Error message

Timeout while waiting for event '{name}'

What it means

Raised by ProgramExecutor.get_meta_info when waiting on a variable's event for `timeout` seconds without the variable being set. In SGL's async interpreter, meta info (finish reason, completion tokens, etc.) is published when a named generation completes; timing out means the producer never set that variable.

Source

Thrown at python/sglang/lang/interpreter.py:366

            self._execute(expr)

    def sync(self):
        if self.use_thread:
            self.queue.join()

    def get_var(self, name):
        if name in self.variable_event:
            self.variable_event[name].wait()
        return self.variables[name]

    def set_var(self, name, value):
        self.variables[name] = value

    def get_meta_info(self, name, timeout=None):
        if name in self.variable_event:
            got = self.variable_event[name].wait(timeout)
            if not got:
                raise TimeoutError(f"Timeout while waiting for event '{name}'")
        ret = self.meta_info.get(name, None)
        return ret

    def fork(
        self,
        size: int = 1,
        position_ids_offset: Optional[List[int]] = None,
    ):
        if size > 1 and str(self.text_):
            self.submit(SglCommitLazy())

        self.sync()
        size = int(size)

        exes = [
            StreamExecutor(
                self.backend,
                self.arguments,

View on GitHub (pinned to 0132848349)

Solutions

1. Increase or omit the timeout (blocking wait) if generation is legitimately slow
2. Verify the variable name matches an actual `name=` on a gen/select in the SGL program
3. Check for exceptions in the executor thread/branch that would prevent the variable from ever being set
4. Pass timeout=None to wait indefinitely when correctness matters more than latency

Example fix

# before
meta = state.get_meta_info("answer", timeout=1)
# after
meta = state.get_meta_info("answer", timeout=30)  # or None to block until set

# before waiting, confirm the variable will be produced
assert name in state.stream_executor.variables or name in declared_gen_names, f"{name} is never set"

try:
    meta = state.get_meta_info(name, timeout=30)
except TimeoutError:
    logger.warning("%s not ready; retrying", name)
    meta = state.get_meta_info(name, timeout=60)

When it happens

Trigger: Calling get_meta_info(name, timeout=N) where `name` was never bound by a select/gen with that name, the generating branch errored out before setting the variable, or the timeout is shorter than model latency (especially with forked/parallel branches).

Common situations: Retrieving meta info for a variable whose generation failed silently; fork() branches racing with the main thread; too-aggressive timeouts under load or long max_new_tokens; typo in the variable name.

Understand the failure class

• Timeouts: ETIMEDOUT, deadlines, and hung requests — what actually expires when a request times out.

Related errors

• Waiting for main node timeout!
• DeepGEMM Kernels compilation timeout.\n\nFeel free and pleas
• Server failed to start within the timeout period.
• Failed to edit image: {str(e)}
• Failed to generate image: {str(e)}

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/80eb31fcf538ab91. Report an issue: GitHub.