Re: ZFS operations hanging, but no visible errors?

That would, indeed, print things as they happen, so if nothing's happening, ...

I believe "sysctl kstat.zfs.misc.dbgmsg" would give you all currently
logged ones.

- Rich

On Fri, Nov 5, 2021 at 1:00 PM Chris Ross <cross+freebsd@distal.com> wrote:
>
>
>
> > On Nov 5, 2021, at 12:39, Fabian Keil <freebsd-listen@fabiankeil.de> wrote:
> > You can check with "procstat -kk" where the hanging
> > processes are stuck.
>
> Running prostate -kk on the rsync that was hung, then killed, then SIGKILL’d shows:
>
> procstat -kk 35220
>   PID    TID COMM                TDNAME              KSTACK
> 35220 102499 rsync               -                   mi_switch+0xc1 _sleep+0x1cb vm_wait_doms+0xe2 vm_wait_domain+0x51 vm_domain_alloc_fail+0x86 vm_page_alloc_domain_after+0x7e uma_small_alloc+0x58 keg_alloc_slab+0xba zone_import+0xee zone_alloc_item+0x6f abd_alloc_chunks+0x61 abd_alloc+0x102 arc_hdr_alloc_abd+0xb0 arc_hdr_alloc+0x11e arc_read+0x4f4 dbuf_issue_final_prefetch+0x108 dbuf_prefetch_impl+0x3d0 dmu_zfetch+0x558
>
>
> >
> > The output of:
> > dtrace -qn 'zfs-dbgmsg {printf("%Y: %s\n", walltimestamp, stringof(arg0))}'
> > could be useful as well.
>
> I’ve run
>
> % sudo dtrace -qn 'zfs-dbgmsg {printf("%Y: %s\n", walltimestamp, stringof(arg0))}’
>
> But, it’s yielding no output.  Is that normal because it outputs information about operations (which aren’t happening), or should it’s output have been immediate?
>
> - Chris