On Sun, Apr 7, 2019 at 12:30 PM Tharen Abela <abela.tha...@gmail.com> wrote: > > The gist of the problem is that I am allocating an object in the runtime, > (which I refer to as the batch struct), and the GC is deallocating the > object, even though a reference is being kept in a slice (similar to allp and > allm). > While allocating, I call acquirem to prevent the GC being triggered, during > which I append the batch pointer to the slice. > > From running `GODEBUG=gccheckmark=1` I know that the batch object allocated, > was being freed, yet when it crashes it says the object is being marked > (hence marking a freed object). > > Now my intention is to keep the batch allocation till the end of the program, > keeping it in an extra batch queue, so it should not be freed. > > Thinking about it now, I am not sure if the deallocation occurs after the > work of the program is finished and is winding down, by de-allocating > everything, but a reference is still kept in allb, so a double free will > occur, OR, > what I have been assuming so far, that this takes place while work is > incomplete so the GC is incorrectly de-allocating a batch object still in use. > > Another thing to take note of, is that the batch in P is referenced by a > uintptr, I'm not sure how that might affect it.
That is going to be your problem. The GC only tracks values with live pointers. A value of type `uintptr` can not be a live pointer. The runtime can only get away with the `guintptr`, `muintptr` and `puintptr` types because it knows that there are existing other pointers to all G and P values (in the allgs and allp slices and the allm linked list). If there is ever any moment that your batch objects are only referenced by `uintptr` values and not by a value of pointer type, then the garbage collector can collect it. Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
