> For the complete documentation index, see [llms.txt](https://docs.eventoframework.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.eventoframework.com/evento-framework/eventobundle/consumerstatestore/inmemoryconsumerstatestore.md).

# InMemoryConsumerStateStore

The in-memory consumer state implementation keeps all consumer state — checkpoints, locks, saga instances, dead events, and dedupe windows — in concurrent in-process collections. Because nothing is persisted, state is lost on application restart, which makes it ideal for development, tests, and demos where durability is not a concern.

{% hint style="warning" %}
**Changed in Evento v2.** There is no longer a single `InMemoryConsumerStateStore` class wired via `setConsumerStateStoreBuilder`. The in-memory backing is now the set of in-memory implementations of the five consumer SPIs, composed for you by `ConsumerEngineConfig.inMemory(...)`. See [ConsumerStateStore](/evento-framework/eventobundle/consumerstatestore.md) for the SPI overview.
{% endhint %}

## In-memory implementations (`evento-common`)

| SPI                  | In-memory implementation     |
| -------------------- | ---------------------------- |
| `ConsumerStateStore` | `InMemoryConsumerStateStore` |
| `ConsumerLock`       | `InMemoryConsumerLock`       |
| `SagaStateStore`     | `InMemorySagaStateStore`     |
| `DeadEventQueue`     | `InMemoryDeadEventQueue`     |
| `DedupeStore`        | `InMemoryDedupeStore`        |

## Usage

In-memory is the default backing. You can set it explicitly with the `ConsumerEngineConfig::inMemory` factory:

```java
EventoBundle.Builder.builder()
    .setBasePackage(MyApplication.class.getPackage())
    .setConsumerEngineConfigBuilder(ConsumerEngineConfig::inMemory)
    // ...
    .start();
```

If you omit `setConsumerEngineConfigBuilder` entirely, the bundle falls back to `ConsumerEngineConfig::inMemory` at startup, so the call above is equivalent to leaving it unset.

{% hint style="warning" %}
**Important.** All checkpoints, saga state, dead events, and dedupe windows live only in memory and are lost when the JVM restarts. For production, use the durable JDBC backing — see [PostgresConsumerStateStore](/evento-framework/eventobundle/consumerstatestore/postgresconsumerstatestore.md) or [MysqlConsumerStateStore](/evento-framework/eventobundle/consumerstatestore/mysqlconsumerstatestore.md).
{% endhint %}