I looked through this, and I don’t think the there is anything needed other than this PR. Eventually jstack creates a VM_PrintThreads command which calls the threads.cpp code.
> On Jun 4, 2024, at 3:52 PM, Iñigo Mediavilla <imedi...@gmail.com> wrote: > > Hello, > > While there's ongoing work on: > > https://github.com/openjdk/jdk/pull/19482 > <https://github.com/openjdk/jdk/pull/19482> > > to add the stack trace of mounted virtual threads to the `jcmd <pid> > Thread.print` command, I'm starting to think about how I could do to print > the stack trace for virtual threads from `jstack` but I'm not sure about what > would be the best approach, so I'd be happy to get people's thoughts on the > topic. > > Based on what I've seen `jstack` seems to fetch a ThreadList of JavaThreads > and then relies on a bunch of Java code that uses attribute offsets to get > the values of certain attributes of the JavaThread in the VM. With those > attributes the java code can obtain the data that it requires about the > threads, their monitors and also to get the latest frame in the stack to be > able to iterate the stack. If I were to follow the same principle, I'd have > to replicate the code that was added to the VM to read the stack chunks of > virtual threads in Java, knowing that it looks like that the JVM code had to > be written for multiple CPU architectures, I'm a bit concern about how > complex following that approach would be. > > I considered following the approach used by `ThreadDumper.java`, that relies > on `ThreadContainers` to get the virtual threads and then iterates over > `Thread.getStackTrace` for the virtual thread. But I don't think that would > work because I don't think the `ThreadContainers` can be accessed from > `Jstack`. > > So I'm basically a bit blocked, and I think that I'd need some help from > people that have followed loom more closely and have a clearer view of things > and can probably provide me with hints on how to approach the problem > differently. > > Thanks in advance for your help. > > Best > > Íñigo Mediavilla Saiz > >
