Quickstart

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from nemo.lens import NemoLensConfig, setup_telemetry
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config = NemoLensConfig.from_env()
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handle = setup_telemetry(config, rank=0, world_size=1)
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# handle.tracer — OTel Tracer (real on exporting rank, no-op elsewhere)
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# handle.meter  — OTel Meter
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# handle.is_exporting — whether this rank exports

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from nemo.lens import managed_span, trace_fn, span_cm
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# Group-gated context manager — cheap when disabled (gated by a frozenset lookup)
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with managed_span('step', 'train.step', iteration=42) as span:
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    do_training_step()
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    if span is not None:
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        span.set_attribute('loss', compute_loss())
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# Group-gated decorator — no re-indentation
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@trace_fn('forward_backward', 'train.forward_backward')
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def forward_pass(batch):
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    ...
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# Simple ungated context manager — always creates a span
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with span_cm('demo.evaluate', tracer=handle.tracer):
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    ...

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try:
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    ...  # your training loop
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finally:
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    handle.shutdown()

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import time
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from nemo.lens import NemoLensConfig, setup_telemetry, managed_span
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def main():
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    config = NemoLensConfig.from_env()
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    handle = setup_telemetry(config, rank=0, world_size=1)
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    try:
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        with managed_span('job', 'demo.job'):
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            for i in range(5):
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                with managed_span('step', 'demo.step', iteration=i):
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                    time.sleep(0.1)
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    finally:
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        handle.shutdown()
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if __name__ == "__main__":
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    main()