On Wed, Jul 3, 2019 at 1:32 PM K.S. Bhaskar <ksbhas...@gmail.com> wrote: > > https://github.com/golang/go/issues/13347#issuecomment-158568326 seems to > suggest runtime.KeepAlive() is not needed but it does not seem definitive. > > If there is a function such as the one below (from > https://gitlab.com/YottaDB/Lang/YDBGo/blob/47f5960d03b2c00ae33222ec1d3bdc60a98226c1/buffer_t.go#L151) > in an application that has Go structures with pointers to C structures and > which uses Finalizers to free the C structures when the Go structures are > collected, is the runtime.KeepAlive(ibuft) required to guarantee that ibuft > is never collected by the Go garbage collector until after the return from > Free()? > > // Calls C.free on any C memory owned by this internalBuffer > > func (ibuft *internalBufferT) Free() { > > printEntry("internalBufferT.Free()") > > if nil == ibuft { > > return > > } > > cbuftptr := ibuft.cbuft > > if nil != cbuftptr { > > // ydb_buffer_t block exists - free its buffer first if it > exists > > if nil != cbuftptr.buf_addr { > > C.free(unsafe.Pointer(cbuftptr.buf_addr)) > > } > > C.free(unsafe.Pointer(cbuftptr)) > > ibuft.cbuft = nil > > } > > runtime.KeepAlive(ibuft)
In the exact code I don't think the runtime.KeepAlive is needed, because the assignment "ibuft.cbuft = nil" should keep ibuft alive. But if I were writing that code I would definitely write the runtime.KeepAlive. Follow a simple rule: if you use runtime.SetFinalizer on instances of a type, then always use runtime.KeepAlive in every method of that type. It costs you essentially nothing and may save your program from memory corruption. 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. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcV-TyZ_t7p%2BZrKbNbpA%3DOEqzg2KhuZrvqO%3DP6vEJYhUFw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
