Comments on: Creation, dynamic loading and instrumentation with javaagents http://dhruba.name/2010/02/07/creation-dynamic-loading-and-instrumentation-with-javaagents/ Maximum Zeal ~ Emphatic prose on indulged fascinations Tue, 13 Mar 2012 03:08:43 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Joe Walp http://dhruba.name/2010/02/07/creation-dynamic-loading-and-instrumentation-with-javaagents/comment-page-1/#comment-42091 Joe Walp Sat, 11 Feb 2012 05:48:08 +0000 http://dhruba.name/?p=1516#comment-42091 Thanks for publishing this. It helped me get lombok [1] working [2] in dev mode with Google Plugin for Eclipse: [1] http://projectlombok.org/ [2] the workaround http://code.google.com/p/googleappengine/issues/detail?id=4122#c4 Thanks for publishing this. It helped me get lombok [1] working [2] in dev mode with Google Plugin for Eclipse:

[1] http://projectlombok.org/
[2] the workaround
http://code.google.com/p/googleappengine/issues/detail?id=4122#c4

]]> By: Roshan P Koshy http://dhruba.name/2010/02/07/creation-dynamic-loading-and-instrumentation-with-javaagents/comment-page-1/#comment-28438 Roshan P Koshy Thu, 07 Jul 2011 14:16:05 +0000 http://dhruba.name/?p=1516#comment-28438 Thanx for the help.. However i dont know how to load java agnet dynamically... I hav seen the result of static loading ...and how the result of dynamic loading comes?is it by entering command similar to staticloading? Thanx for the help.. However i dont know how to load java agnet dynamically… I hav seen the result of static loading …and how the result of dynamic loading comes?is it by entering command similar to staticloading?

]]> By: bdaddy http://dhruba.name/2010/02/07/creation-dynamic-loading-and-instrumentation-with-javaagents/comment-page-1/#comment-28044 bdaddy Tue, 28 Jun 2011 16:12:01 +0000 http://dhruba.name/?p=1516#comment-28044 Great end-to-end tutorial! I can't wait to give this technology a spin. I imagine using this VirtualMachine.loadAgent()/TransformClassFile mechanism to wholesale replace an existing class implementation with another. For example, say i want to simply comment out or add a couple lines to a method in the class. It seems like this sort of "wholesale dynamic class patching" would be conceptually easier than bytecode manipulation via ASM or whatever. I envision a tool with the usage of: jpatch Are you aware of such a tool? Is there some fundamental roadblock I'm overlooking that would prevent such a tool from working as expected? (Granted I can imagine that weird things would happen if the bytecode change was too radical.) Also, when using loadAgent() to inject the agent into a running JVM, does the JVM automatically cycle the class file transfer through all already loaded classes? This doesn't appear to be clear from what I've read of the documentation so far. Guess I'll find out for myself when I give this stuff a try. Great end-to-end tutorial! I can’t wait to give this technology a spin.

I imagine using this VirtualMachine.loadAgent()/TransformClassFile mechanism to wholesale replace an existing class implementation with another. For example, say i want to simply comment out or add a couple lines to a method in the class. It seems like this sort of “wholesale dynamic class patching” would be conceptually easier than bytecode manipulation via ASM or whatever.

I envision a tool with the usage of:

jpatch

Are you aware of such a tool? Is there some fundamental roadblock I’m overlooking that would prevent such a tool from working as expected? (Granted I can imagine that weird things would happen if the bytecode change was too radical.)

Also, when using loadAgent() to inject the agent into a running JVM, does the JVM automatically cycle the class file transfer through all already loaded classes? This doesn’t appear to be clear from what I’ve read of the documentation so far. Guess I’ll find out for myself when I give this stuff a try.

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