oven-sh/bun · error · Error

traced only ${order.length} functions, expected at least ${m

Error message

traced only ${order.length} functions, expected at least ${minFunctions} — the tracer or the symbol table is broken, and a near-empty order file silently costs the win

What it means

Final sanity gate in generateOrderFile: after every workload, fewer than minFunctions (default MIN_FUNCTIONS) unique symbol names were collected. A near-empty order file would silently forfeit the link-order startup win, so the generator fails loudly instead of writing a useless artifact.

Source

Thrown at scripts/orderfile/generate.ts:328

      let unresolved = 0;
      for (const address of readTrace(out, workload.name)) {
        const names = symbols.get(address);
        if (!names) {
          unresolved++;
          continue;
        }
        for (const name of names) {
          if (seen.has(name)) continue;
          seen.add(name);
          order.push(name);
        }
      }
      const note = unresolved ? ` (${unresolved} unresolved)` : "";
      log(`  ${workload.name.padEnd(21)} +${order.length - before} functions${note}`);
    }

    if (order.length < minFunctions) {
      throw new Error(
        `traced only ${order.length} functions, expected at least ${minFunctions} — ` +
          `the tracer or the symbol table is broken, and a near-empty order file silently costs the win`,
      );
    }

    const header = [
      `# ${darwin ? "ld -order_file" : "lld --symbol-ordering-file"}: functions bun executes while starting up,`,
      "# in first-entry order, so they land together at the front of .text.",
      "# Generated by scripts/orderfile/generate.ts — not committed.",
      `# ${order.length} functions from ${workloads.length} workloads.`,
    ];
    writeFileSync(outPath, header.join("\n") + "\n" + order.join("\n") + "\n");
    return { count: order.length, outPath };
  } finally {
    rmSync(scratch, { recursive: true, force: true });
  }
}

View on GitHub (pinned to 8c5296ac45)

Solutions

1. Re-run with verbose enabled and read the per-workload counts — a large `(unresolved)` number means address/symbol mismatch
2. Ensure the bun-profile passed to nm is byte-identical to the binary the workloads executed (rebuild once, then generate in one step)
3. Confirm the tracer actually preloads in every workload (see error 172 diagnosis)
4. Only if you intentionally traced a much smaller binary, lower minFunctions accordingly

Example fix

// before — silently accepts a near-empty order file
generateOrderFile({ buildDir });

// after — gate explicitly on a realistic floor
generateOrderFile({ buildDir, minFunctions: 10_000, verbose: true });

import { spawnSync } from "node:child_process";

// Cheap coverage probe: how many text symbols can this nm even see for this binary?
const r = spawnSync(process.env.NM || "nm", [bunProfile]);
const visible = r.stdout.toString().split("\n").filter((l) => /^[0-9a-f]+ [tT] \S+$/.test(l)).length;
if (visible < minFunctions) throw new Error(`Symbol table only exposes ${visible} functions — minFunctions ${minFunctions} can never be met`);

try {
  return generateOrderFile({ buildDir, verbose: true });
} catch (err) {
  if (/traced only \d+ functions/.test(String(err))) {
    console.error("Order file would be near-empty — verify tracer preload and that nm read the exact binary that ran");
  }
  throw err;
}

When it happens

Trigger: Most traced addresses failing to resolve because the symbol table came from a different build than the binary executed; the tracer not loading in workloads (each trace would be empty or all-unresolved); a stripped or mismatched bun-profile. Watch the verbose per-workload `+N functions (X unresolved)` lines to see where resolution dies.

Common situations: Rebuilding the binary between generating the symbol table and running workloads; mixing binaries (default name vs custom exeName); tracer silently not preloading on hardened setups.

Related errors

• ${nm} failed on ${bunProfile} ${r.stderr}
• ${nm} reported no text symbols — is ${bunProfile} stripped?
• workload "${name}" wrote a truncated trace
• workload "${name}" wrote an invalid trace
• workload "${name}" recorded no entries — is the tracer loadi

AI-assisted analysis of oven-sh/bun@8c5296ac45 (2026-08-16). Data as JSON: /api/errors/c7815f50f09b148e. Report an issue: GitHub.