Zoltan Borok-Nagy has posted comments on this change. (
Change subject: IMPALA-6416: extend Thread::Create to track instance id
Patch Set 4:
PS4, Line 115: system_thread_id_
> Are you saying that thread_debug_info_ pointer may point to stray
Yes, I think that can potentially happen.
> If that's the case, maybe we shouldn't keep that pointer
> but instead have a way to traverse TDIs and find it if still
We can use the system thread id to find the parent thread and then its TDI if
it still exists.
I also added a copy of the parent thread name. Even if the parent thread exits,
at least we will now what was its name.
We can also check if parent thread name equals to the TDI's thread name that we
found via the system thread id. If they're not the same, we'll know that the
parent thread was re-cycled in some way.
PS4, Line 119: boost::thread::id boost_thread_id_;
: int64_t system_thread_id_ = 0;
> I'm not sure what you mean by "switch to the parent thread
I was just thinking of a GDB session. GDB prints out the system thread id for
each thread, so we can traverse the threads quickly if we know the ID. It can
be also useful if we write a script for that and we don't want to iterate
through all the threads.
> I don't think I fully understand the tradeoffs. Just seems
> confusing to have multiple IDs and I don't understand how each of
> these fields helps in debugging. Perhaps some comments attached to
> them explaining how one can use them for debugging would help?
I removed boost::thread::id, and added the parent's thread name. I think it is
more clear, and knowing the parent thread name can be useful on its own. And we
can also use it to verify the parent thread.
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Gerrit-Owner: Zoltan Borok-Nagy <borokna...@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhe...@cloudera.com>
Gerrit-Reviewer: Lars Volker <l...@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Reviewer: Zoltan Borok-Nagy <borokna...@cloudera.com>
Gerrit-Comment-Date: Wed, 14 Feb 2018 17:32:14 +0000