Test ROBOT with GraalVM

[jamesaoverton]

GraalVM includes a tool called native-image that can convert a Java JAR file to a platform-native binary that can be executed without needing a JVM installed. This could simplify the ROBOT installation instructions to just: download the binary for your platform. However there may be a performance hit.

[beckyjackson]

This is cool! I was able to build an image and it runs fine, but I haven't tested performance against the JAR yet. That said, the image I built is not a standalone image and can only be run from within the ROBOT directory. We can build a standalone image using the --no-fallback option, but when I try to run this image, it fails:

Failed to instantiate SLF4J LoggerFactory
Reported exception:
java.lang.NoClassDefFoundError
	at org.apache.log4j.Category.class$(Category.java:118)
	at org.apache.log4j.Category.<clinit>(Category.java:118)
	at java.lang.Class.ensureInitialized(DynamicHub.java:552)
	at java.lang.Class.ensureInitialized(DynamicHub.java:552)
	at org.apache.log4j.LogManager.<clinit>(LogManager.java:82)
	at org.slf4j.impl.Log4jLoggerFactory.<init>(Log4jLoggerFactory.java:66)
	at org.slf4j.impl.StaticLoggerBinder.<init>(StaticLoggerBinder.java:72)
	at org.slf4j.impl.StaticLoggerBinder.<clinit>(StaticLoggerBinder.java:45)
	at org.slf4j.LoggerFactory.bind(LoggerFactory.java:150)
	at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:124)
	at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:412)
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:357)
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:383)
	at org.obolibrary.robot.CommandManager.<clinit>(CommandManager.java:19)
	at org.obolibrary.robot.CommandLineInterface.initManager(CommandLineInterface.java:21)
	at org.obolibrary.robot.CommandLineInterface.<clinit>(CommandLineInterface.java:13)
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Category
	at java.lang.Class.forName(DynamicHub.java:1433)
	at java.lang.Class.forName(DynamicHub.java:1408)
	... 16 more

Could somebody else try building an image using --no-fallback to see if this is something weird on my system, or if it's a problem with log4j?

[jamesaoverton]

Thanks! Google has some results for graal slf4j. It seems to be a common problem, but I'm not sure what the right solution is. I guess I'd suggest trying to upgrade slf4j to 1.7.32 first.

[beckyjackson]

Ah, I should have checked that first. Upgrading slf4j-log4j doesn't resolve the problem. It seems like it has something to do with this comment. The doc link that user provided no longer works, I think this is what he was trying to reference.

[beckyjackson]

It looks like this issue was fixed in log4j-2.13.1 (org.apache.log4j.Logger). We're using org.slf4j.Logger. Should I try replacing all our loggers with org.apache.log4j.Logger and then trying native-image again?

[jamesaoverton]

I guess it's worth a try. I think we used slf4j because OWLAPI does: https://github.com/owlcs/owlapi/blob/version5/pom.xml#L115

[beckyjackson]

2.13.1 has another issue where org.apache.log4j.Category cannot be found. Since the original issue seems to have been introduced in 2.8, I tried using 2.7 and ran into the same problem. It looks like Category was deprecated a long time ago according to the docs. I can run ROBOT just fine from the JAR but the native image seems to want this Category class for some reason.