Interest in Java based attach provider implementation?

[Philippe Marschall]

Hello

I further pursued the approach

- Rebased the Linux implementation [1], implemented the permission check 
using JSR 203 and the Unix domain sockets using JEP 380.
- Applied the same changes to the AIX implementation [2].
- Switched Linux to an FFM based kill implementation [3], completely 
getting rid of JNI.
-  Updated the macOS implementation [4], implemented the permission 
check using JSR 203 and the Unix domain sockets using JEP 380.
- Switched macOS to an FFM based kill and sysctl implementation [5], 
completely getting rid of JNI.

I ran the serviceability test suite on Linux and macOS and it passes. I 
manually verified that I can attach to JVMs using local builds.

I could not test on AIX.

  [1] 
https://github.com/marschall/jdk/commit/3a7796daadad7c9d2d85e9e4623f170baecc0e41
  [2] 
https://github.com/marschall/jdk/commit/962729e0bfb6b7d86af303f25c6670d407d1d2d9
  [3] 
https://github.com/marschall/jdk/commit/7b5f1bf6f55458a7f69f50b8fdf4986e22202559
  [4] 
https://github.com/marschall/jdk/commit/93372a124eca6078fde5597c2498b381a4ef5dfa
  [5] 
https://github.com/marschall/jdk/commit/c5faf9655bbb85cc3ed9b2a7ef15b08ab83d1d8b

Cheers
Philippe

On 20.04.22 22:13, Philippe Marschall wrote:
> Hello
> 
> I hope this is the right mailing list. I recently had a look at the
> Linux attach provider implementation and could not help but noticing
> that a large part, if not all of it, could be replaced with Java.
> Besides getting rid of the C code this should allow us to unify the AIX,
> Linux and macOS implementations under a single Unix implementation.
> 
> The permission check can be implemented using JSR 203 [1] to access uid,
> gid and file mode and using jdk.internal.misc.VM to get the euid and egid.
> 
> Reading and writing to Unix domain sockets can be done through JEP 380 [2].
> 
> Sending SIGQUIT to a process could in theory done through JEP 102 [3]
> however sending SIGQUIT to self is currently blocked. This is required
> for the self attach mechanism. There a very small C function is still
> needed for now, this is hopefully portable.
> 
> I did a small prototype [4]. The tier1 suite runs and I can attach to a
> local JVM.
> 
> The overhead will likely be a bit higher as we go through more JDK
> abstractions.
> 
>   [1] https://jcp.org/en/jsr/detail?id=203
>   [2] https://openjdk.java.net/jeps/380
>   [3] https://openjdk.java.net/jeps/102
>   [4]
> https://github.com/marschall/jdk/ 
> commit/207dac7e4d1bd65450bbd2c9e14d33fc34b7cebc
> 
> Cheers
> Philippe