NPE in hotswap agent on an embedded Jetty 9

[Евгений Науменко]

Hello everyone,

I've tried DCEVM recently and it works like a charm. As a next step I'd like to integrate hotswap agent, but it keeps throwing NPEs on application start:

Listening for transport dt_socket at address: 8000

HOTSWAP AGENT: 22:45:7.174 INFO (org.hotswap.agent.HotswapAgent) - Loading Hotswap agent {0.3.0-SNAPSHOT} - unlimited runtime class redefinition.

Exception in thread "main" java.lang.reflect.InvocationTargetException

        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

        at java.lang.reflect.Method.invoke(Method.java:606)

FATAL ERROR in native method: processing of -javaagent failed

        at sun.instrument.InstrumentationImpl.loadClassAndStartAgent(InstrumentationImpl.java:382)

        at sun.instrument.InstrumentationImpl.loadClassAndCallPremain(InstrumentationImpl.java:397)

Caused by: java.lang.NullPointerException

        at org.hotswap.agent.config.PluginConfiguration.<init>(PluginConfiguration.java:44)

        at org.hotswap.agent.config.PluginManager.init(PluginManager.java:95)

        at org.hotswap.agent.HotswapAgent.premain(HotswapAgent.java:42)

        ... 6 more

Application itself is a jar file with an embedded Jetty 9 inside launched by Gradle as follows:

javaexec {
    main = '-jar'
    args jar.archivePath
    jvmArgs = ['-XXaltjvm=dcevm',
               "-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8000",
               "-javaagent:${configurations.hot_swap.asPath}=autoHotswap=true"]
}

I've tried it on different machines, with or without plugins, with DCEVM installed as altvm or as a replacement, but to no avail.

Here's the simplified version of the project I'm trying to run. Calling './gradlew runJar' results in an aforementioned exception.

Any advice and suggestions will be greatly appreciated.

[vladimir dvorak]

The fix (Issue 97) should be available in repo. Do clone last version from repo and build hotswap-agent.jar.

[Евгений Науменко]

Thanks a lot, the latest version seems to have the problem fixed.