[lldb-dev] Can Process hold a TargetSP instead of a Target&?
Pavel Labath via lldb-dev
lldb-dev at lists.llvm.org
Fri Aug 28 14:01:08 PDT 2015
I think it should be a weak_ptr if anything. Target already holds a
shared_ptr of the process, and you will get pointer loops otherwise.
Couldn't you make sure the debug thread exits (and processes all
events) before the Target gets deleted (e.g. shut it down in
Process::Finalize() or somewhere...)? If there is currently an
invariant that Process should never outlive its Target (which would
seem to be implied by the fact it holds a Target&), I would prefer if
it can be preserved.
On 28 August 2015 at 19:34, Zachary Turner via lldb-dev
<lldb-dev at lists.llvm.org> wrote:
> We've been seeing races during shutdown of inferiors for months, and I
> finally tracked it down to the fact that Process holds a Target&. When an
> inferior is exiting on Windows, we will get a notification of this and we
> try to do various cleanup related with the target. But there are times
> where the Target gets deleted even when the Process is still around, due to
> some interactions between our debug loop and the timing of when certain
> debug events that get sent by the operating system.
> As a result, the race leads to us getting one of the notifications from the
> OS and us trying to access the target, which is stored by reference leading
> to a crash.
> It seems like a purely mechanical change to make Process hold a TargetSP
> instead of a Target&. I've already started down this patch locally, but I
> want to make sure there are no objections or concerns before I continue down
> this path, since it's kind of mundane work.
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