jimingham wrote: > > You are right, TryAllThreads defaults to True. > > Not using TryAllThreads is actually dangerous in the general case. For > > instance, you can have the thread you run take a lock, then call some code > > that tries another lock that is held by a thread we aren't running. That > > times out so we cancel the execution evaluation but since we don't in > > general know about all the locking strategies available on any given > > platform, we don't know to unlock the first lock, and that will cause the > > program to deadlock later on if anybody tries to get the first lock again. > > If you do the same thing with TryAllThreads set to true, then when the > > expression deadlocks on the running thread, we give a chance for the thread > > holding the second lock to release it, and the evaluation goes on to > > succeed, releasing the first lock on the way out. > > Also, a very common workflow in debugging is to stop somewhere at a > > breakpoint, run a couple of expressions and continue, and you don't really > > care about the state of other threads. So true is the right default value. > > There is an overload of CreateValueFromExpression that takes an > > EvaluteExpressionOptions, and if you are calling code internally you should > > be using that one because you really should think about how you want the > > expression to run. > > Yeah, I see your point. VS debugger takes the other design decision to not > run all threads, so it is notorious for expression evaluation causing IDE to > deadlock or hang by accident during stepping. Eventually, they designed a UI > to not automatically evaluate expressions in watch window during stop but has > a "dangerous" button next to each expression saying click at your own risk.
The earliest dogfooding team for lldb - way back before it was public - was the clang team not surprisingly. clang developers live by `dump()` so having a robust expression evaluator was one of the very early requirements! BTW, in general I don't suggest having one of the hardest features to implement in your project be the first hard requirement... https://github.com/llvm/llvm-project/pull/108414 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
