Spring startup performance issues
Not much you can do about the performance there, I guess you aren't concerned about the startup in production environment, but the startup time of your tests*. Two tips:
- Review that your test-appcontext only uses the minimally required components of your app
- instead of having a list of component-scan directives, use one, with a comma-separated value like this: base-package="com.package.one,com.package.two..."
Auto discovery of annotated classes currently requires to scan all classes in the specified package(s) and can take a long time, a known problem of the current class loading mechanism.
Java 9 is going to help here with Jigsaw.
From the Java Platform Module System requirements by Mark Reinold, http://openjdk.java.net/projects/jigsaw/spec/reqs/ :
Efficient annotation detection — It must be possible to identify all of the class files in a module artifact in which a particular annotation is present without actually reading all of the class files. At run time it must be possible to identify all of the classes in a loaded module in which a particular annotation is present without enumerating all of the classes in the module, so long as the annotation was retained for run time. For efficiency it may be necessary to specify that only certain annotations need to be detectable in this manner. One potential approach is to augment a module’s definition with an index of the annotations that are present in the module, together with an indication of the elements to which each annotation applies. To limit the size of the index, only annotations which themselves are annotated with a new meta-annotation, say @Indexed, would be included.
Question: How many (in %) of the classes in the directories are Spring Beans?
Answer: I'm not really sure (it's a really big project) , but from what i saw i believe it's arround 90 to 100%, since xml and properties files are isolated in separate locations)
If the problem is really the component scan and not the bean initializing process itself (and I highly doubt that), then the only solution I can imagine is to use Spring XML configuration instead of component scan. - (May you can create the XML file automatically).
But if you have many classes and 90% - 100% of them are Beans, then, the reduction of scanned files will have a maximal improvement of 10%-0%.
You should try other ways to speed up your initialization, may using lazy loading or any lazy loading related techniques, or (and that is not a joke) use faster hardware (if it is not a stand alone application).
A easy way to generate the Spring XML is to write a simple spring application that uses the class path scanning like your original application. After all Beans are initialize, it iterates through the Beans in the Spring Context, check if the bean belongs to the important package and write the XML Config for this bean in a file.