> ## Documentation Index
> Fetch the complete documentation index at: https://jetxl.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# write_sheets_arrow

> Write several sheets to one file, in parallel

```python theme={null}
jet.write_sheets_arrow(arrow_sheets, filename, num_threads) -> None
```

## Parameters

<ParamField path="arrow_sheets" type="list[dict]" required>
  One dictionary per sheet. Requires `data` and `name`, and every other key is a `write_sheet_arrow` option.
</ParamField>

<ParamField path="filename" type="str" required>Output path.</ParamField>

<ParamField path="num_threads" type="int" required>
  Threads for XML generation. Required and positional, with no default. Omitting it raises a `TypeError`.
</ParamField>

## The sheet dictionary

<ParamField path="data" type="Arrow table" required>Sheet contents.</ParamField>
<ParamField path="name" type="str" required>Tab label.</ParamField>

Then any option from [`write_sheet_arrow`](/reference/write-sheet-arrow) as a key: `styled_headers`, `freeze_rows`, `column_formats`, `tables`, `charts`, `images`, `conditional_formats`, `data_validations`, `tab_color`, and the rest.

```python theme={null}
jet.write_sheets_arrow(
    [
        {"data": df1.to_arrow(), "name": "Sales",
         "styled_headers": True, "tab_color": "00B050"},
        {"data": df2.to_arrow(), "name": "Costs",
         "auto_width": True, "hidden_columns": [2]},
    ],
    "report.xlsx",
    num_threads=2,
)
```

## Returns

`None`.

## Notes

<AccordionGroup>
  <Accordion title="Thread count" icon="microchip">
    Parallelism is per sheet, so more threads than sheets gains nothing. `min(os.cpu_count(), len(sheets))` is the sensible ceiling.
  </Accordion>

  <Accordion title="Shared style registry" icon="palette">
    Jetxl deduplicates styles across sheets, so repeating identical formatting is cheap.
  </Accordion>

  <Accordion title="Sheet order" icon="arrow-down-1-9">
    Tabs appear in list order, and Excel opens on the first.
  </Accordion>
</AccordionGroup>