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Office Oxide

Batch Processing

Office Oxide is fast enough that for most batch jobs the bottleneck is disk I/O, not parsing. A typical Word document extracts in 0.8ms — meaning a single thread chews through ~1,000 files per second.

This guide covers the patterns that scale: serial loops for small jobs, thread pools for medium ones, async I/O when you’re streaming from S3 or HTTP.

Serial loop — the right default

For up to a few thousand files on local disk, a plain serial loop is the simplest and often fastest choice. You avoid the overhead of spawning workers and the contention of parallel disk reads.

Python

from pathlib import Path
from office_oxide import Document

for src in Path("corpus").rglob("*"):
    if src.suffix.lower() in {".docx", ".xlsx", ".pptx", ".doc", ".xls", ".ppt"}:
        with Document.open(src) as doc:
            text = doc.plain_text()
        src.with_suffix(".txt").write_text(text)

Rust

use std::path::Path;
use office_oxide::Document;
use walkdir::WalkDir;

for entry in WalkDir::new("corpus") {
    let entry = entry?;
    let path = entry.path();
    if let Some(ext) = path.extension().and_then(|e| e.to_str()) {
        if matches!(ext.to_ascii_lowercase().as_str(),
                    "docx" | "xlsx" | "pptx" | "doc" | "xls" | "ppt") {
            let doc = Document::open(path)?;
            std::fs::write(path.with_extension("txt"), doc.plain_text())?;
        }
    }
}

JavaScript

import { readdirSync, statSync, writeFileSync } from 'node:fs';
import { join, extname } from 'node:path';
import { Document } from 'office-oxide';

const exts = new Set(['.docx', '.xlsx', '.pptx', '.doc', '.xls', '.ppt']);

function* walk(dir) {
  for (const name of readdirSync(dir)) {
    const full = join(dir, name);
    if (statSync(full).isDirectory()) yield* walk(full);
    else yield full;
  }
}

for (const src of walk('corpus')) {
  if (!exts.has(extname(src).toLowerCase())) continue;
  using doc = Document.open(src);
  writeFileSync(src.replace(/\.\w+$/, '.txt'), doc.plainText());
}

WASM (browser, user-uploaded files)

import { WasmDocument } from 'office-oxide-wasm';

// <input type="file" multiple accept=".docx,.xlsx,.pptx,.doc,.xls,.ppt">
async function extractAll(fileList) {
  const results = [];
  for (const file of fileList) {
    const data = new Uint8Array(await file.arrayBuffer());
    const fmt = file.name.split('.').pop().toLowerCase();
    const doc = new WasmDocument(data, fmt);
    try {
      results.push({ name: file.name, text: doc.plainText() });
    } finally {
      doc.free();
    }
  }
  return results;
}

Runs entirely client-side — files never leave the browser, ideal for privacy-sensitive batch tasks.

Go

package main

import (
    "os"
    "path/filepath"
    "strings"

    officeoxide "github.com/yfedoseev/office_oxide/go"
)

var exts = map[string]bool{
    ".docx": true, ".xlsx": true, ".pptx": true,
    ".doc": true, ".xls": true, ".ppt": true,
}

func main() {
    filepath.Walk("corpus", func(path string, info os.FileInfo, err error) error {
        if err != nil || info.IsDir() { return err }
        if !exts[strings.ToLower(filepath.Ext(path))] { return nil }
        doc, err := officeoxide.Open(path)
        if err != nil { return nil } // skip unreadable
        defer doc.Close()
        text, _ := doc.PlainText()
        return os.WriteFile(strings.TrimSuffix(path, filepath.Ext(path))+".txt", []byte(text), 0644)
    })
}

C#

using OfficeOxide;

var exts = new HashSet<string> { ".docx", ".xlsx", ".pptx", ".doc", ".xls", ".ppt" };

foreach (var src in Directory.EnumerateFiles("corpus", "*", SearchOption.AllDirectories))
{
    if (!exts.Contains(Path.GetExtension(src).ToLowerInvariant())) continue;
    using var doc = Document.Open(src);
    File.WriteAllText(Path.ChangeExtension(src, ".txt"), doc.PlainText());
}

Parallel — for large corpora

When you have tens of thousands of files and a fast SSD, parallelism helps. Be careful: too many workers will saturate disk and hurt throughput.

Python (ProcessPoolExecutor)

from concurrent.futures import ProcessPoolExecutor
from pathlib import Path
from office_oxide import Document

def process(path: Path) -> None:
    with Document.open(path) as doc:
        path.with_suffix(".md").write_text(doc.to_markdown())

paths = [p for p in Path("corpus").rglob("*")
         if p.suffix.lower() in {".docx", ".xlsx", ".pptx", ".doc", ".xls", ".ppt"}]

with ProcessPoolExecutor(max_workers=8) as ex:
    for _ in ex.map(process, paths):
        pass

The Python binding releases the GIL during native parsing, so a ThreadPoolExecutor works too — but processes give better isolation if a single document panics.

Rust (rayon)

use rayon::prelude::*;
use office_oxide::Document;

paths.par_iter().for_each(|path| {
    if let Ok(doc) = Document::open(path) {
        let _ = std::fs::write(path.with_extension("md"), doc.to_markdown());
    }
});

Rayon’s default thread count matches your CPU; it’s almost always the right setting.

Go (goroutine pool)

package main

import (
    "os"
    "path/filepath"
    "runtime"
    "strings"
    "sync"

    officeoxide "github.com/yfedoseev/office_oxide/go"
)

func main() {
    var paths []string
    filepath.Walk("corpus", func(p string, info os.FileInfo, err error) error {
        if err != nil || info.IsDir() { return err }
        ext := strings.ToLower(filepath.Ext(p))
        if ext == ".docx" || ext == ".xlsx" || ext == ".pptx" { paths = append(paths, p) }
        return nil
    })

    jobs := make(chan string)
    var wg sync.WaitGroup
    for i := 0; i < runtime.NumCPU(); i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for path := range jobs {
                doc, err := officeoxide.Open(path)
                if err != nil { continue }
                md, _ := doc.ToMarkdown()
                os.WriteFile(strings.TrimSuffix(path, filepath.Ext(path))+".md", []byte(md), 0644)
                doc.Close()
            }
        }()
    }
    for _, p := range paths { jobs <- p }
    close(jobs)
    wg.Wait()
}

C# (Parallel.ForEach)

using OfficeOxide;

var exts = new HashSet<string> { ".docx", ".xlsx", ".pptx" };
var paths = Directory.EnumerateFiles("corpus", "*", SearchOption.AllDirectories)
    .Where(p => exts.Contains(Path.GetExtension(p).ToLowerInvariant()))
    .ToList();

Parallel.ForEach(paths, new ParallelOptions { MaxDegreeOfParallelism = Environment.ProcessorCount }, path =>
{
    try
    {
        using var doc = Document.Open(path);
        File.WriteAllText(Path.ChangeExtension(path, ".md"), doc.ToMarkdown());
    }
    catch (OfficeOxideException) { /* skip unreadable */ }
});

JavaScript (Promise.all)

import { readdirSync, statSync } from 'node:fs';
import { join, extname } from 'node:path';
import { Document } from 'office-oxide';

const exts = new Set(['.docx', '.xlsx', '.pptx', '.doc', '.xls', '.ppt']);

function* walk(dir) {
  for (const name of readdirSync(dir)) {
    const full = join(dir, name);
    if (statSync(full).isDirectory()) yield* walk(full);
    else yield full;
  }
}

const paths = [...walk('corpus')].filter(p => exts.has(extname(p).toLowerCase()));

// Limit concurrency
const CONCURRENCY = 8;
let i = 0;
async function worker() {
  while (i < paths.length) {
    const path = paths[i++];
    using doc = Document.open(path);
    // process doc.toMarkdown() ...
  }
}
await Promise.all(Array.from({ length: CONCURRENCY }, worker));

Async — when files come from elsewhere

If your inputs come from HTTP, S3, or a queue, async I/O wins because the network dominates parsing time. Open from bytes, never from a path.

Python (asyncio + aiohttp)

import asyncio, aiohttp
from office_oxide import Document

async def fetch_and_extract(session, url):
    async with session.get(url) as r:
        data = await r.read()
    fmt = url.rsplit(".", 1)[-1].lower()
    with Document.from_bytes(data, fmt) as doc:
        return doc.plain_text()

async def main(urls):
    async with aiohttp.ClientSession() as session:
        return await asyncio.gather(*(fetch_and_extract(session, u) for u in urls))

Rust (tokio)

use office_oxide::{Document, DocumentFormat};
use std::io::Cursor;

let bytes = reqwest::get(url).await?.bytes().await?;
let fmt = DocumentFormat::Docx;
// Move parsing to a blocking task — extraction is CPU-bound.
let text = tokio::task::spawn_blocking(move || -> office_oxide::Result<String> {
    let doc = Document::from_reader(Cursor::new(bytes.to_vec()), fmt)?;
    Ok(doc.plain_text())
}).await??;

JavaScript (fetch + concurrency limit)

import { Document } from 'office-oxide';

async function fetchAndExtract(url) {
  const res = await fetch(url);
  const buf = Buffer.from(await res.arrayBuffer());
  const fmt = url.split('.').pop().toLowerCase();
  using doc = Document.fromBytes(buf, fmt);
  return doc.plainText();
}

const CONCURRENCY = 16;
const queue = [...urls];
const results = [];
await Promise.all(Array.from({ length: CONCURRENCY }, async () => {
  while (queue.length) {
    const url = queue.shift();
    results.push(await fetchAndExtract(url));
  }
}));

Go (HTTP fan-out)

package main

import (
    "io"
    "net/http"
    "strings"
    "sync"

    officeoxide "github.com/yfedoseev/office_oxide/go"
)

func fetchAndExtract(url string) (string, error) {
    resp, err := http.Get(url)
    if err != nil { return "", err }
    defer resp.Body.Close()
    data, err := io.ReadAll(resp.Body)
    if err != nil { return "", err }

    fmt := url[strings.LastIndex(url, ".")+1:]
    doc, err := officeoxide.OpenFromBytes(data, fmt)
    if err != nil { return "", err }
    defer doc.Close()
    return doc.PlainText()
}

func main() {
    urls := []string{ /* ... */ }
    sem := make(chan struct{}, 16) // concurrency cap
    var wg sync.WaitGroup
    for _, u := range urls {
        wg.Add(1)
        sem <- struct{}{}
        go func(url string) {
            defer wg.Done()
            defer func() { <-sem }()
            text, _ := fetchAndExtract(url)
            _ = text // process...
        }(u)
    }
    wg.Wait()
}

C# (HttpClient + async)

using OfficeOxide;

using var http = new HttpClient();

async Task<string> FetchAndExtract(string url)
{
    var data = await http.GetByteArrayAsync(url);
    var fmt = url[(url.LastIndexOf('.') + 1)..].ToLowerInvariant();
    using var doc = Document.FromBytes(data, fmt);
    return doc.PlainText();
}

// Limit concurrency with SemaphoreSlim
var sem = new SemaphoreSlim(16);
var tasks = urls.Select(async url =>
{
    await sem.WaitAsync();
    try { return await FetchAndExtract(url); }
    finally { sem.Release(); }
});
var results = await Task.WhenAll(tasks);

Memory tips

  • For very large XLSX files, build with the mmap feature in Rust (features = ["mmap"]) and call Document::open_mmap to avoid copying the whole archive into the heap.
  • Keep one Document open at a time per worker. Each handle holds the parsed structure in memory; closing it (drop in Rust, exit the with block in Python, close()/using in JS) releases it.
  • For LLM ingestion at scale, prefer to_markdown() over to_html() — Markdown produces smaller output and better LLM throughput downstream.

See also