this is effectively what dynamic agent loading enables, which
https://openjdk.org/jeps/451 proposes to disable.
Rgds
- Larry Cable
On 7/16/23 10:09 PM, David Holmes wrote:
On 17/07/2023 12:21 pm, Yi Yang wrote:
Actually, this is not a very new and strange idea. I often encounter
similar needs in actual debugging and troubleshooting. In addition,
this feature has also been implemented in some external tools
(https://arthas.aliyun.com/en/doc/ognl.html
<https://arthas.aliyun.com/en/doc/ognl.html>). It would be very
convenient for problem diagnosis if JDK natively had this capability
Okay please take this discussion to serviceability-dev - cc'd.
Thanks,
David
------------------------------------------------------------------
From:David Holmes <david.hol...@oracle.com>
Send Time:2023 Jul. 13 (Thu.) 20:34
To:"YANG, Yi" <qingfeng...@alibaba-inc.com>; jdk-dev
<jdk-...@openjdk.org>
Subject:Re: Proposal: Post debug Java code to target JVM and exec it
On 13/07/2023 8:57 pm, Yi Yang wrote:
> Proposal: Post debug Java code to target JVM and exec it
>
> Hello, I have an early idea to post a piece of Java code to a
local JVM
> process via jcmd or jexec, like this:
>
> jcmd VM.exec Debug.java
> jexec Debug.java
>
> class Debug {
> public static void main(){
> ApplicationProperties c = loadClass("ApplicationProperties");
> // print static field of running Java program
> System.out.println(ApplicationProperties.field1);
> // call static method of running Java program
> ApplicationProperties.printAll();
> // ....
> }
> }
>
> With this approach, we can do some useful things, such as:
> - Get some runtime data of the program
> - Troubleshoot Java problems
> - In rare cases, it can also assist in JVM problem diagnosis
>
> To protect the attach listener, we may need to create a new
ExecThread
> at JVM startup and execute Debug::main in this thread. Do you
have any
> comments on this idea?
So basically you want the ability to ask a running JVM to execute an
arbitrary piece of java code. That may have some uses but in general
seems incredibly dangerous - how would you safeguard such a
facility?
Cheers,
David
> Thank you.
