dtrace, jstack and lang/openjdk7 or 8

[Dmitry Samersoff]

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Jung-uk Kim,

> BTW, 'jstack -m <pid>' is invalid command, i.e., it does not work with
> a running process.  You need to set '-F' option to force it.

jstack -m turns on -F internally so command it self is OK.

The problem is jstack -F uses serviceability agent (see
hotspot/agent) as a backend and as far as I know this backend
is not ported to FreeBSD

- -Dmitry


On 2015-03-26 23:42, Jung-uk Kim wrote:
> On 03/25/2015 19:02, Johannes Dieterich wrote:
> > Hi,
>
> > I am currently trying to get dtrace to work with either
> > java/openjdk7 or java/openjdk8 (as per Brendan Gregg's howto:
> > http://www.brendangregg.com/blog/2014-06-12/java-flame-graphs.html).
>
> >  Unfortunately, I get exactly what he describes: I am missing
> > everything inside the JVM. I suspect this has to do with jstack()
> > not working. The bundled jstack executable (yes, I know that they
> > are only vaguely related) also seems to work only so-so. Basically,
> > I can get a working stack trace without a variable, with -l, but
> > not with -m, and not with -F. It causes exceptions like this:
>
> > $ /usr/local/openjdk7/bin/jstack -m 84749
> ...
> > So, what I am asking is: anybody out there got a working setup for
> > dtrace+openjdk on FreeBSD? If so, it would be fantastic if you
> > could post the necessary steps!
>
> jstack from java/openjdk8 works fine AFAICT.  Unfortunately, dtrace is
> unimplemented for FreeBSD.
>
> BTW, 'jstack -m <pid>' is invalid command, i.e., it does not work with
> a running process.  You need to set '-F' option to force it.
>
> % /usr/local/openjdk8/bin/jstack
> Usage:
>     jstack [-l] <pid>
>         (to connect to running process)
>     jstack -F [-m] [-l] <pid>
>         (to connect to a hung process)
>     jstack [-m] [-l] <executable> <core>
>         (to connect to a core file)
>     jstack [-m] [-l] [server_id@]<remote server IP or hostname>
>         (to connect to a remote debug server)
>
> Options:
>     -F  to force a thread dump. Use when jstack <pid> does not respond
> (process is hung)
>     -m  to print both java and native frames (mixed mode)
>     -l  long listing. Prints additional information about locks
>     -h or -help to print this help message
>
>
> Jung-uk Kim
> _______________________________________________
> freebsd-java at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-java
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