Repeatable vs. Non-Repeatable Streaming

Choose between non-repeatable and repeatable streaming to optimize flow performance in Mule. Non-repeatable streams let you read the payload once; repeatable streams support multiple or concurrent reads. Maximize flow performance by choosing the streaming strategy that matches how your flow consumes the payload:

A non-repeatable stream (read payload only once) or
A repeatable stream (read payload more than once)

Non-Repeatable Streaming

The non-repeatable strategy disables repeatable streams. If your use case requires reading the payload only once, use the non-repeatable-stream parameter in the connector. See this example:

<file:read path="exampleFile.json">
  <non-repeatable-stream />
</file:read>

Repeatable Streaming

Alternatively, if your use case requires reading the payload multiple times or concurrently, you can choose among these two strategies:

File-store streaming
In-memory streaming

File-Store Repeatable Stream

When using the file-store repeatable stream strategy, configure these parameters to optimize performance:

inMemorySize
Defines the buffer size stored in memory before Mule writes to disk.
bufferUnit
Defines the unit of measurement for the buffer size.
eagerRead
Determines whether Mule reads the buffer as soon as data is available (true) or waits until the buffer fills (false). The default value is false.

When configuring inMemorySize, consider these trade-offs:

Configure a larger buffer size to reduce disk writes and improve performance. However, larger buffers require more memory and can reduce the number of concurrent requests your application can handle.
Configure a smaller buffer size to reduce memory usage at the cost of slower response time.

This example configures a file-store repeatable stream with a buffer size of 1 MB:

[source,xml,linenums]

<file:read path="bigFile.json"> <repeatable-file-store-stream inMemorySize="1" bufferUnit="MB" eagerRead="true"/> </file:read>

Always run performance tests to find the optimal buffer size for your specific use case.

=== In-Memory Repeatable Stream

When using the in-memory repeatable stream strategy, to manage larger or smaller files, configure these parameters:

* `initialBufferSize` +
Defines the initial buffer size.
* `bufferSizeIncrement` +
Defines how much the buffer grows each time it expands.
* `maxInMemorySize` +
Defines the maximum amount of content stored in memory.
* `bufferUnit` +
Defines the unit of measurement for buffer values.
* `eagerRead` +
Defines whether Mule reads the buffer as soon as data is available (`true`) or waits until the buffer fills (`false`). The default value is `false`. The default buffer size is 512 KB. Adjust the buffer configuration based on your payload size and expected concurrency.

This example configures an in-memory repeatable stream with an initial size of 512 KB, which grows at a rate of 256 KB and allows up to 2000 KB (2 MB) of content in memory:

[source,xml,linenums]

<file:read path="exampleFile.json"> <repeatable-in-memory-stream initialBufferSize="512" bufferSizeIncrement="256" maxInMemorySize="2000" bufferUnit="KB"/> </file:read>

Always run performance tests to find the optimal buffer size for your specific use case.

== See Also

* xref:streaming-about.adoc[Streaming in Mule Apps]