# streaming-huge-json

Companion code for the rewritten post
[Jackson Streaming API and JsonNode (Jackson 3)](https://ankurm.com/jackson-streaming-api-jsonnode/).

A self-contained Maven module (not part of the root build). It generates a 1 GiB JSON array,
then counts the `ERROR` records four ways under fixed `-Xmx` limits.

```
Jackson   3.2.4   (tools.jackson.core:jackson-databind, GA on Maven Central 2026-10-18)
JDK       Temurin 25.0.5 (LTS)
```

| Class | What it shows |
|---|---|
| [`GenerateHugeJson`](src/main/java/com/ankurm/jackson3/streaminghuge/GenerateHugeJson.java) | Writing 1 GiB with `JsonGenerator` under `-Xmx64m` |
| [`Scan`](src/main/java/com/ankurm/jackson3/streaminghuge/Scan.java) | `stream`, `hybrid`, `tree`, `bind` (and the broken `hybrid-naive`) |
| [`NestedTrap`](src/main/java/com/ankurm/jackson3/streaminghuge/NestedTrap.java) | The flat-object loop breaking on nested JSON; `skipChildren()` fix |
| [`TruncatedFile`](src/main/java/com/ankurm/jackson3/streaminghuge/TruncatedFile.java) | What a cut-off file does to streaming vs tree |
| [`ReadLimits`](src/main/java/com/ankurm/jackson3/streaminghuge/ReadLimits.java) | Default `StreamReadConstraints` values |

```bash
cd streaming-huge-json
./scripts/run-all.sh --quick   # small demos only
./scripts/run-all.sh           # also generates target/huge.json (1 GiB, git-ignored) and runs the ladder
```

Captured output is in [`output/`](output). Memory figures are from one run on a 2-CPU, 8 GB
container; `peakUsed` is sampled `total - free` heap and includes garbage not yet collected.
Timings vary between runs; the pass/fail pattern per `-Xmx` is the stable part.

Note on `output/bench.txt`: the `tree -Xmx= 6144 MB KILLED` line comes from a separate manual run
(the first ladder run printed a blank line for it because the OS killed the JVM, exit 137);
`scripts/bench.sh` now records that case itself.