trouble with java -Xpatch

[Michael Rasmussen]

But retransform in this phase would still be subject to the same
limitations about no structural changes I assume? Meaning no adding of
members etc.

My preferred solution would still be if adding (and changing) Xpatch would
be possible during OnLoad, as that should solve all my problems.

/Michael
On Apr 4, 2016 14:30, "Alan Bateman" <Alan.Bateman at oracle.com> wrote:

> On 04/04/2016 12:09, Michael Rasmussen wrote:
>
>> So in order to patch any of the well-known preloaded classes, I will need
>> to prepatch them, put them in a folder/jar, and then need to ask the user
>> to specify the -Xpatch jvm option, seeing as I don't have the option to
>> neither patch them via CFLH, nor add -Xpatch myself from jvmti?
>>
>> As things stand then -Xpatch is the only way to have patched versions of
> the preloaded classes loaded in the primordial phase.
>
> That said, we have enough in place where we could look at allowing
> GetLoadedClasses and RetransformClasses in the start phase. When combined
> with can_generate_early_vmstart then it would allow agents to patch classes
> before any bytecode executes. As per the warnings in the spec then any
> instrumentation at this point requires great care as it's still too early
> in the VM startup for code outside of java.base to execute.
>
> -Alan
>