# Fix the locale QA agent crashing on an XLIFF file over 50MB

## TL;DR

The agent loads the whole XLIFF into memory, so stream it instead. A 50MB XML file becomes hundreds of megabytes as a DOM, and the agent OOMs. Parse with a SAX or streaming reader, process unit by unit, and memory stays flat.

## The error

```text
Locale QA agent: out of memory parsing 68MB XLIFF
run crashed before any QA check ran
```

## Fix it

### Step 1: Confirm the file size and structure

```bash
ls -lh big.xliff && grep -c "trans-unit" big.xliff | head -1
```

Expected: You see the size and unit count.

### Step 2: Switch the parser to streaming

```bash
grep -n "parse\|DOMParser\|xml2js" scripts/qa-agent.js | head -5
```

Expected: You find the load-whole-file call to replace.

### Step 3: Process unit by unit

```bash
node -e "console.log('pattern: sax stream, on trans-unit close run the QA checks, then discard the node')"
```

Expected: Memory stays flat regardless of file size.

### Step 4: Re-run the QA checks

```bash
node scripts/qa-agent.js --file big.xliff | tail -3
```

Expected: The checks complete on the full file.

## When to use this

- A locale QA agent crashes on a large XLIFF
- Out of memory during XML parsing

## When NOT to use this

- The file is small but parsing is slow, check the parser
- The QA checks are wrong, fix the checks

## Tool and version compatibility

- SAX/streaming XML parsers in Node
- XLIFF 1.2 trans-unit streaming

## Variant phrasings

### XLIFF 2.0 instead of 1.2

Same approach, stream on unit elements. The element name changes, the pattern does not.

### need random access to units

Index first with a streaming pass, then seek. Two passes beat one OOM.

## Why it happens

DOM parsers build the entire document tree in memory with heavy per-node overhead. A 68MB file easily needs over a gigabyte as a DOM, exceeding the agent's heap, while a streaming parser holds one unit at a time.

## Edge cases

- Validate the XML separately with xmllint, streaming parsers are lenient
- Some checks need cross-unit context, buffer a window not the whole file
- Split giant files by unit count as a preprocessing step if streaming is hard

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_GEnqcp7J5uCrwvpcrAZOXA