[[processing]]
=== Processing Details

Understanding how {ls} works and how components interrelate can help you make
better decisions when you are setting up or adjusting your {ls} environment.
This section is designed to elevate concepts to assist with that level of
knowledge.

NOTE: This is a new section. We're still working on it.

[float] 
[[event-ordering]] 
==== Event ordering 

By design and by default, {ls} does not guarantee event order. Reordering can
occur in two places:

* Events within a batch can be reordered during filter processing.
* In-flight batches can be reordered when one or more batches are processed faster than
others. 

When maintaining event order is important, use a single worker and set
'pipeline.ordered => true'.
This approach ensures that batches are computed one-after-the-other, and
that events maintain their order within the batch.

[float] 
[[order-setting]] 
===== 'pipeline.ordered' setting

The `pipeline.ordered` setting in <<logstash-settings-file,logstash.yml>>
gives you more control over event ordering for single worker pipelines.

`auto` automatically enables ordering if the `pipeline.workers` setting is also
set to `1`. `true` will enforce ordering on the pipeline and prevent logstash
from starting if there are multiple workers. `false` will disable the processing
required to preserve order. Ordering will not be guaranteed, but you save the
processing cost required to preserve order.

[float] 
[[pipeline-init-time]] 
==== Java pipeline initialization time

The Java pipeline initialization time appears in the startup logs at INFO level.
Initialization time is the time it takes to compile the pipeline config and
instantiate the compiled execution for all workers.

include::reserved-fields.asciidoc[]