Thanks for digging into this. Maybe a better option would be to have IRExecutionUnit hold a SymbolContextScope, rather than a SymbolContext. We started out with SymbolContext's because they were convenient but they hold too many things alive so when we run into SymbolContext's we've been converting them to the SymbolContextScope's when possible. I can't see any need for the IRExecutionUnit to hold the module alive, so long as it handles failure to get the SymbolContext gracefully, which shouldn't be hard.
Jim > On Feb 21, 2017, at 9:03 AM, Pavel Labath via lldb-dev > <lldb-dev@lists.llvm.org> wrote: > > Hello all, > > I've been debugging the newly added TestStepOverBreakpoint.py, which > has been failing on windows, for a very prosaic reason: after the test > completes, we are unable to run "make clean" because lldb still holds > the file open. > > After some debugging, I've found that this happens because the test > case stores the SBBreakpoint object in a member variable of the python > test case class. The breakpoint class ends up transitively holding a > reference to the main executable module, which prevents the module > from being garbage-collected when the target is destroyed. > > For reference, the full ownership chain is something like: > StepOverBreakpointTestCase(python) => SBBreakpoint => Breakpoint => > BreakpointLocation => LLVMUserExpression => IRExecutionUnit => > SymbolContext => Module. > > To get the test working, we need to break this chain somewhere. A > couple of places I see are: > - BreakpointLocation: Remove the compiled expression reference when > the target is destroyed (AFAICS, it is used as a cache to avoid > recomputing the expression every time. It can be theoretically > recomputed if needed, but that shouldn't be necessary as the target is > destroyed anyway) > > - SBBreakpoint: make SBBreakpoint hold a weak_ptr to the Breakpoint > object. When the target is destroyed, the SBBreakpoint object becomes > invalid (One doesn't cannot do anything useful with the breakpoint > once the target has been deleted anyway). > > - StepOverBreakpointTestCase: Have the test not store the breakpoints > in the test case object. Basically, declare that this is not a bug, > and it's the users responsibility to clean up necessary objects. > > Any thoughts on what is the appropriate solution here? > > cheers, > pavel > _______________________________________________ > lldb-dev mailing list > lldb-dev@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
