Hi Philippe,
There is an ongoing effort about "Panamization" (that is, adapting it to
use FFM instead of JNI) of native code in the JDK in general. This is
discussed on the core-libs-dev mailing list. I've cc:ed them. I think it
would be beneficial if you coordinate your efforts with the Panamization
effort.
/Magnus
On 2025-06-15 17:43, Philippe Marschall wrote:
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
