[GEODE-800] Geode's classloading mechanism is unable to resolve classes found within nested jars

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0.0-incubating
• Fix Version/s: 1.5.0
• Component/s: configuration, gfsh
• Labels: ClassLoader DeployCommand deploy gfsh pull-request-available
• Assignee: Unassigned
• Reporter: Jens Deppe
• Created: 20/Jan/16 17:22
• Updated: 09/Apr/18 22:37
• Resolved: 13/Feb/18 19:33

Description

This issue is particularly evident when using Geode in a Spring Boot app which creates an 'über' jar containing all dependent jars.

When Geode is launched in this context, the following errors can be seen:

[warn 2016/01/20 08:53:29.431 PST <main> tid=0xd] (tid=13 msgId=0) Required Commands classes were not loaded. Check logs for errors.
java.lang.IllegalStateException: Required Commands classes were not loaded. Check logs for errors.
        at com.gemstone.gemfire.management.internal.cli.CommandManager.raiseExceptionIfEmpty(CommandManager.java:249)
        at com.gemstone.gemfire.management.internal.cli.CommandManager.loadCommands(CommandManager.java:188)
        at com.gemstone.gemfire.management.internal.cli.CommandManager.<init>(CommandManager.java:86)
        at com.gemstone.gemfire.management.internal.cli.CommandManager.getInstance(CommandManager.java:278)
        at com.gemstone.gemfire.management.internal.cli.CommandManager.getInstance(CommandManager.java:258)
        at com.gemstone.gemfire.management.internal.cli.remote.CommandProcessor.<init>(CommandProcessor.java:58)
        ...

The problem here is in ClasspathScanLoadHelper.getClasses(). In this method we call:

Enumeration<URL> resources = ClassPathLoader.getLatest().getResources(packagePath);

However getResources() doesn't just work against the 'latest' classloader, but also considers the thread context classloader. In the case of a Spring Boot app, Spring does provide such a classloader and getResources is able to find the necessary resources CommandMarker classes. (These classes are found within a nested jar. For ex. jar:file:/Users/jdeppe/src/woddrive/WodDrive-GF-Server/target/WodDriveGFServer.jar!/lib/gemfire-core-1.0.0-incubating-SNAPSHOT.jar!/com/gemstone/gemfire/management/internal/cli/commands). This is all fine, but subsequent code doesn't consider classes (or packages) within nested jars, and in addition, when classes actually get resolved, the thread context classloader (where those resources might have come from) is not considered.

Issue Links

• links to: GitHub Pull Request #1430