Unable to reattach to puma worker

[mdkent]

Maybe this is something unique to puma workers but we can't attach to them more than once:

a@b:/u/apps/c/current$ bundle exec rbtrace -p 7879 -e "1+1"
*** attached to process 7879
>> 1+1
=> 2
*** detached from process 7879
a@b:/u/apps/c/current$ ipcs

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages
0xffffe139 1769473    app        666        0            0

If attach gdb here I can see it running the rbtracer_detach() cleanup just fine in the extension.

Now the subsequent call fails:

a@b:/u/apps/c/current$ bundle exec rbtrace -p 7879 -e "1+1"
Error: argument --pid (process already being traced?).
Try --help for help.
a@b:/u/apps/c/current$ ipcs

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages
0xffffe139 1769473    app        666        256          1

from some light gdb and stracing it appears that attempt #2 is sending SIGURG and writing to the message queue, but the rbtracer.so extension is no longer firing the signal handler. I can't figure out why.