[WW-3689] NullPointerException coming from Settings / LegacyPropertiesConfigurationProvider (thread-safety issue?)

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.14, 2.2.3.1
• Fix Version/s: 2.3.15

Environment

Any; multi-core machines tend to demonstrate the problem more readily though.

• Flags: Patch
• Assignee: Lukasz Lenart
• Reporter: James Abley
• Created: 04/Oct/11 10:59
• Updated: 08/Nov/13 06:54
• Resolved: 23/May/13 05:34

Description

When running a load test, we intermittently see failures with this stack trace (the line numbers are for 2.0.14, but we also see this with 2.2.3.1):

Exception in thread "MultiThreadTestRunner-5" java.lang.NullPointerException
	at org.apache.struts2.config.Settings.get(Settings.java:175)
	at org.apache.struts2.config.Settings.getDefaultInstance(Settings.java:293)
	at org.apache.struts2.config.Settings.getInstance(Settings.java:109)
	at org.apache.struts2.config.LegacyPropertiesConfigurationProvider.register(LegacyPropertiesConfigurationProvider.java:67)
	at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reload(DefaultConfiguration.java:131)
	at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:52)
	at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:395)
	at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:452)
	at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:205)
	at com.example.platform.test.servlet.OurServlet.handleRequest(OurServlet.java:64)

or

Caused by: java.lang.NullPointerException
	at org.apache.struts2.config.LegacyPropertiesConfigurationProvider.loadSettings(LegacyPropertiesConfigurationProvider.java:86)
	at org.apache.struts2.config.LegacyPropertiesConfigurationProvider.register(LegacyPropertiesConfigurationProvider.java:69)
	at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reload(DefaultConfiguration.java:131)
	at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:52)
	at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:395)
	at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:452)
	at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:205)

Our suspicion is that the initialisation isn't thread-safe; we've not seen this failure on older, single-processor / single-core machines.

Issue Links

• relates to: WW-4152 Concurrency issue in strust2 app deployed in JBoss AS7