Ahead-of-time compilation for MyBatis Mappings

[tobiasschaefer]

Currently, during startup of an application most time is lost when building the process engine. Specifically, it's during the MyBatis Initialization when parsing the XML mappings which takes several seconds.

Idea: use the ahead-of-time compilation concept of Micronaut to parse the MyBatis Mappings during build time and create a Java-Code representation.

This will reduce the startup time tremendously.

[tobiasschaefer]

Some ideas

• let's first serialize the configuration (maybe even to an absolute path) and if a parameter is set then deserialize the configuration (and skip reading the XML configuration). If this POC is successful (start is fast) we can continue to move the serialization to the build phase
• let's use Kryo to serialize the configuration object
• we might be able to exclude some dependencies from the runtime, e.g. dependencies of MyBatis e.g. XML parser
• once the startup is faster we can use inspectIT, see also Performance-Analysis of Camunda Process Engine #19, to find the next bottle neck