[YARN-9595] FPGA plugin: NullPointerException in FpgaNodeResourceUpdateHandler.updateConfiguredResource()

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.3.0
• Component/s: nodemanager
• Target Version/s: 3.3.0
• Assignee: Peter Bacsko
• Reporter: Peter Bacsko
• Created: 03/Jun/19 14:11
• Updated: 04/Jun/19 09:04
• Resolved: 04/Jun/19 09:04

Description

YARN-9264 accidentally introduced a bug in FpgaDiscoverer. Sometimes currentFpgaInfo is not set, resulting in an NPE being thrown:

2019-06-03 05:14:50,157 INFO org.apache.hadoop.service.AbstractService: Service NodeManager failed in state INITED; cause: java.lang.NullPointerException
java.lang.NullPointerException
        at org.apache.hadoop.yarn.server.nodemanager.containermanager.resourceplugin.fpga.FpgaNodeResourceUpdateHandler.updateConfiguredResource(FpgaNodeResourceUpdateHandler.java:54)
        at org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl.updateConfiguredResourcesViaPlugins(NodeStatusUpdaterImpl.java:358)
        at org.apache.hadoop.yarn.server.nodemanager.NodeStatusUpdaterImpl.serviceInit(NodeStatusUpdaterImpl.java:190)
        at org.apache.hadoop.service.AbstractService.init(AbstractService.java:164)
        at org.apache.hadoop.service.CompositeService.serviceInit(CompositeService.java:108)
        at org.apache.hadoop.yarn.server.nodemanager.NodeManager.serviceInit(NodeManager.java:459)
        at org.apache.hadoop.service.AbstractService.init(AbstractService.java:164)
        at org.apache.hadoop.yarn.server.nodemanager.NodeManager.initAndStartNodeManager(NodeManager.java:869)
        at org.apache.hadoop.yarn.server.nodemanager.NodeManager.main(NodeManager.java:942)

The problem is that in FpgaDiscoverer, we don't set currentFpgaInfo if the following condition is true:

if (allowed == null || allowed.equalsIgnoreCase(
        YarnConfiguration.AUTOMATICALLY_DISCOVER_GPU_DEVICES)) {
      return list;
    } else if (allowed.matches("(\\d,)*\\d")){
    ...

Solution is simple: initialize it in both code-paths.

Unit tests should be enhanced to verify that it's set properly.