NullPointerException when trying to perform a hotswap in tomcat7

[Phil Armstrong]

I am trying to get hotswap working with tomcat7.0.11.0.  I am using java version 1.7.0_75 that has been patched.   I am running the project through netbeans 8.0.  I followed the instructions at: http://hotswapagent.org/quick-start for the basic stuff and https://groups.google.com/forum/#!topic/hotswapagent/ydW5bQMwQqU for the netbeans specific stuff.  I was able to run a normal stand alone java app with the hotswapagent and everything seemed to work quite well.  I ran it and saw that the agent started and I could modify a class by adding a new method and call that method.  On save everything updated as expected.  

Attempting to do the same thing  for a tomcat application does not seem to be working quite right.  I have modified the tomcat platform in netbeans by adding -XXaltjvm=dcevm -javaagent:<mypathtohotspot>/hotswapjava/hotswap-agent.jar.  When I start tomcat everything appears to start correctly.  I get:

HOTSWAP AGENT: 14:38:50.134 INFO (org.hotswap.agent.config.PluginRegistry) - Plugin 'org.hotswap.agent.plugin.tomcat.TomcatPlugin' initialized in ClassLoader 'WebappClassLoader

  context: /perseus-controller

  delegate: false

  repositories:

    /WEB-INF/classes/

----------> Parent Classloader:

When I go in and make any change to a class however I get the following error:

HOTSWAP AGENT: 14:39:27.562 ERROR (org.hotswap.agent.util.HotswapTransformer) - Error transforming class 'com/ca/perseus/perseuscontrollerclient/JobQueueClient$RequestRetryHandler'.

java.lang.NullPointerException

at org.apache.catalina.loader.WebappClassLoader.findResources(WebappClassLoader.java:1271)

at java.lang.ClassLoader.getResources(ClassLoader.java:1185)

at org.hotswap.agent.config.PluginConfiguration.<init>(PluginConfiguration.java:63)

at org.hotswap.agent.config.PluginManager.initClassLoader(PluginManager.java:154)

at org.hotswap.agent.annotation.handler.OnClassLoadedHandler.transform(OnClassLoadedHandler.java:104)

at org.hotswap.agent.annotation.handler.OnClassLoadedHandler$1.transform(OnClassLoadedHandler.java:76)

at org.hotswap.agent.util.HotswapTransformer.transform(HotswapTransformer.java:129)

at sun.instrument.TransformerManager.transform(TransformerManager.java:188)

at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:424)

I'm not sure what I should be doing here...

[Roy Ling]

I encountered the same problem, any solution on this?

[vladimir dvorak]

Could you build last hotswapagent from github repository please? This problem should be already solved, last official release is little bit obsolete. Anyway you can disable tomcat plugin in hotswap-agent.properties - it helped me.