The multiline codec plugin replaces the multiline filter plugin. The multiline codec is better equipped to handle multi-worker pipelines and threading.
Here’s why. Multiline takes individual lines of text and groups them according to some criteria. Accomplishing this operation in the filter stage is possible only if the pipeline has a single worker. Otherwise, chunks would end up in different workers, and the resulting composition would not make sense.
The multiline codec plugin allows input plugins to create separate codec instances per “identity.” For example, each file or tcp connection can have its own codec instance.