Could you run the C code in its own OS thread by using LockOSThread and then send a signal to that thread directly?
On 15 February 2017 at 18:26, Yucong Sun <sunyuc...@gmail.com> wrote: > Also, my cleanup function must be tied directly with C loop, because > they are sharing the same underlaying memory/state . If I directly > run cleanup() while C loop was running, there could be race. > > So that leaves me with no choice, i must be able to panic on the C > loop's go-routine on async signals, which I can't do with current > tools. > > On Wed, Feb 15, 2017 at 10:21 AM, Yucong Sun <sunyuc...@gmail.com> wrote: >> https://play.golang.org/p/7Vz0o4ZoQF >> >> shows that your code doesn't really work. My understanding is once >> panic reaches the current goroutine's top of callstack, program will >> crash, there are no attempt to call other goroutine's deferred >> function. >> >> So, in order to do what I want, i must be able to trigger some sort >> of inline panic remotely. Note in the C code this is easy, the >> signal handler will interrupt current thread, jump directly to the >> handler code and resume. If I can do that in golang, i will be able >> to trigger a panic in main() and do what I want (or do what the old C >> code does, which i was porting into go) >> >> On Wed, Feb 15, 2017 at 10:14 AM, Yucong Sun <sunyuc...@gmail.com> wrote: >>> Thanks axle, but are you sure the code would work? it is essentially >>> triggering panic on the main go routine while recovering from another >>> goroutine, isn't that impossible? >>> >>> If this is possible, why couldn't I trigger a panic on a goroutine >>> then recover it from main goroutine? >>> >>> On Wed, Feb 15, 2017 at 10:03 AM, Axel Wagner >>> <axel.wagner...@googlemail.com> wrote: >>>> First, the code you wrote here doesn't use os/signal, so you can't really >>>> fault Ian for giving that advice. Here's my understanding: >>>> >>>> In general, there are two kinds of signals: synchronous ones, raised e.g. >>>> by >>>> dereferencing invalid memory. They produce a runtime panic at the site that >>>> produced them in the corresponding goroutine. And asynchronous ones, raised >>>> e.g. by using the kill command or os.Kill. They do not produce a runtime >>>> panic but instead need to be handled via os/signal. >>>> >>>> Now, to "catch" asynchronous panic's, you need to use os/signal and if you >>>> need them to produce a runtime-panic on the goroutine running main, you >>>> need >>>> to read from that channel in main and produce a panic whenever you read a >>>> value. You could, for example, do this: >>>> >>>> func main() { >>>> ch := make(chan os.Signal) >>>> signal.Notify(ch, mySignals) >>>> >>>> errs := make(chan interface{}) >>>> >>>> go func() { >>>> defer func() { >>>> errs <- recover() >>>> }() >>>> for { >>>> C.do_something() >>>> } >>>> }() >>>> >>>> for { >>>> select { >>>> case s := <-ch: >>>> panic(fmt.Sprintf("received signal: %v", s)) >>>> case v := <-errs: >>>> panic(fmt.Sprintf("recovered runtime panic in C-code: %v", v)) >>>> } >>>> } >>>> } >>>> >>>> this will get asynchronous signals via os/signal and synchronous signals in >>>> the C-code raising runtime-panics via recover. >>>> >>>> Now, what is *not* possible, is to somehow recover from runtime panics >>>> caused by synchronous signals in *other* goroutines. The spec is pretty >>>> clear about that; a panic that isn't recovered will cause the program to >>>> crash. >>>> >>>> Hope this helps. >>>> >>>> On Wed, Feb 15, 2017 at 6:44 PM, Yucong Sun <sunyuc...@gmail.com> wrote: >>>>> >>>>> hi, >>>>> >>>>> Maybe I wasn't clear, I am indeed using os.signal package. But it doesn't >>>>> do what I want! I want to trigger a panic in main function , seems there >>>>> is >>>>> no way to do it by using a signal channel . >>>>> >>>>> Thanks >>>>> >>>>> -- >>>>> 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. >>>> >>>> > > -- > 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. -- 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.
