ZFS getting job/task info from a booting zpool

[absduser]

I have an issue I've detailed in a prior post:

https://forums.freebsd.org/threads/62718/

However I'd like to specifically ask the community:

When I run this as the zpool is importing:

# zdb -dddd pool/filesystem  | grep DELETE_QUEUE
zdb: can't open 'pool/filesystem': Device busy

I assume dataset cannot tell me anything because it is pending destroy ...

Specifically, I want to see the process of a pending filesystem destroy that is underway - I can't get that from the filesystem itself because it is being destroyed, but is there anything that zdb can tell me, from the zpool, about how the destruction is progressing?

 

[absduser]

I have figured out a bit of the answer here, but I'm still looking for more info. With dtrace I can get some details, but it's lacking in terms of progress:

# dtrace -q -n 'zfs-dbgmsg{printf("%s\n", stringof(arg0))}'
txg 34628587 open pool version 28; software version 5000/5; uts host 10.3-RELEASE 1003000 amd64
txg 34628587 destroy begin tank/temp (id 3680)
txg 34628588 destroy tank/temp (id 3680)

That's all I get until I run out of memory- and there are no message about that from dtrace or on console.

Does the fact that the output on an earlier boot looked like this:

txg 34628585 open pool version 28; software version 5000/5; uts host 10.3-RELEASE 1003000 amd64
txg 34628585 destroy begin begin tank/temp (id 3680)
txg 34628586 destroy begin tank/temp (id 3680)

mean that progress is being made, or is the txg # incremented with each new operation?