tursodatabase/turso · warning

no CPU samples collected; increase --queries or --seconds

Error message

no CPU samples collected; increase --queries or --seconds

What it means

After stopping the CPU profiler, finish() builds a report and requires at least one collected sample before producing a flamegraph. ensure! in perf/fts/src/profiling.rs:31 fails when report.data is empty, meaning the profiled workload was too short or too light for the sampler to record any frames.

Solutions

1. Increase --queries (search mode) or --seconds (throughput mode) so the run lasts long enough to sample
2. Lower the profiler sampling interval if the profiler configuration allows it
3. Skip profiling for tiny runs: only enable the profiler for realistically sized workloads
4. Confirm the profiler was actually enabled/attached (an enabled profiler with no path or no samples may indicate attachment failure)

Example fix

// before
fts-bench --benchmark search --queries 1 --profile out.svg
// after
fts-bench --benchmark search --queries 100000 --profile out.svg

if queries < 10_000 && seconds.unwrap_or(5.0) < 1.0 { eprintln!("workload too small for CPU profiling; increase --queries or --seconds"); }

When it happens

Trigger: Calling finish() on an enabled profiler whose capture window contained no samples — typically a benchmark run with very few queries (--queries 1) or a sub-second --seconds window, so the sampling interval never fired.

Common situations: Profiling a quick smoke test instead of a real run; high sampling interval combined with tiny workloads; records_worker_cpu_without_rendering_svg-style tests driving a profiler with minimal work; profiler attached but workload finishing before the first tick.

Understand the failure class

Background: EmptyResultError / "no results found": when an API or scraper succeeds but returns zero rows — this error's family across 9 libraries.

Related errors

• BEGIN must start a transaction
• COMMIT must end the transaction
• COMMIT must end the transaction
• connections must be positive
• connections must be positive

AI-assisted analysis of tursodatabase/turso@8d4a589f8d (2026-09-20). Data as JSON: /api/errors/aafcc44acd2b8bf0. Report an issue: GitHub.

Appendix: source

Thrown at perf/fts/src/profiling.rs:31

    #[cfg(any(
        target_arch = "x86_64",
        target_arch = "aarch64",
        target_arch = "riscv64",
        target_arch = "loongarch64"
    ))]
    let builder = builder.blocklist(&["libc", "libgcc", "pthread", "vdso"]);
    Ok(Some(builder.build()?))
}

pub fn finish(profiler: Option<pprof::ProfilerGuard<'static>>, path: Option<&Path>) -> Result<()> {
    let Some(profiler) = profiler else {
        assert!(path.is_none());
        return Ok(());
    };
    let report = profiler.report().build()?;
    drop(profiler);
    let path = path.expect("enabled profiler must have an output path");
    ensure!(
        !report.data.is_empty(),
        "no CPU samples collected; increase --queries or --seconds"
    );
    let mut stacks = BTreeMap::<String, isize>::new();
    for (frames, count) in &report.data {
        let mut names = vec![frames.thread_name_or_id()];
        for frame in frames.frames.iter().rev() {
            for symbol in frame.iter().rev() {
                names.push(symbol.name().replace(';', ":"));
            }
        }
        *stacks.entry(names.join(";")).or_default() += count;
    }
    let mut folded = BufWriter::new(File::create_new(path.with_extension("folded"))?);
    for (stack, count) in stacks {
        writeln!(folded, "{stack} {count}")?;
    }
    folded.flush()?;

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