On Tue, Apr 30, 2019 at 6:33 PM vaastav anand <vaastav.anan...@gmail.com> wrote:
> I have encountered a SIGBUS with go before but I was hacking inside the > runtime and using shared mem with mmap. > > goroutines are assigned IDs incrementally and each goroutine at bare > minimum has 2.1KB stack space in go1.11 down from 2.7KB in go1.10 if I > recall correctly. So, at the very least at that point you could have easily > burnt through at least 7.5GB of memory. I am not sure what could happen if > you somehow exceed the amount of memory available. Seems like that is a > test you could write and see if launching more goroutines than that could > fit in the size of memory could actually cause a SIGBUS. > The stack trace only listed 282 goroutines, which seems about right considering the number of clients that are connected. Its about 3 goroutines per client connection, plus the other stuff in the server. I think it just indicates that I have turned over a lot of client connections over time. > > On Monday, 29 April 2019 23:25:52 UTC-7, Justin Israel wrote: >> >> >> >> On Tue, Apr 30, 2019 at 6:09 PM vaastav anand <vaastav...@gmail.com> >> wrote: >> >>> Ok, so in the 2nd piece of code you posted, is some request being pushed >>> onto some OS queue? If so, is it possible that you may be maxing the queue >>> out and then pushing something else into it and that could cause a SIGBUS >>> as well.... This seems super farfetched tho but it is hard to debug without >>> really knowing what the application might really be doing. >>> >> >> I want to say that I really appreciate you taking the time to try and >> give me some possible ideas, even though this is a really vague problem. I >> had only hoped someone had encountered something similar. >> >> So that line in the SIGBUS crash is just trying to add a subscription to >> a message topic callback in the nats client connection: >> https://godoc.org/github.com/nats-io/go-nats#Conn.Subscribe >> It's pretty high level logic at my application level. >> >> One thing that stood out to me was that in the crash, the goroutine id >> number was 3538668. I had to double check to confirm that the go runtime >> just uses an insignificant increasing number. I guess it does indicate that >> the application turned over > 3 mil goroutines by that point. I'm wondering >> if this is caused by something in the gnatsd embedded server ( >> https://github.com/nats-io/gnatsd/tree/master/server) since most the >> goroutines do come from that, with all the client handling going on. If we >> are talking about something that is managing very large queues, that would >> be the one doing so in this application. >> >> >>> >>> On Monday, 29 April 2019 22:57:40 UTC-7, Justin Israel wrote: >>>> >>>> >>>> >>>> On Tue, Apr 30, 2019 at 5:43 PM vaastav anand <vaastav...@gmail.com> >>>> wrote: >>>> >>>>> I'd be very surprised if the anonymous goroutine is the reason behind >>>>> a SIGBUS violation. >>>>> So, if I remember SIGBUS correctly, it means that you are issuing a >>>>> read/write to a memory address which is not really addressable or it is >>>>> misaligned. I think the chances of the address being misaligned are very >>>>> low.....so it really has to be a non-existent address. >>>>> It can happen if you have try to access memory outside the region >>>>> mmaped into your application. >>>>> If your application has any kind of mmap or shared memory access, I >>>>> would start there. >>>>> In any case your best bet is to somehow reproduce the bug consistently >>>>> and then figure out which memory access is causing the fault. >>>>> >>>> >>>> My application isn't doing anything with mmap or shared memory, and my >>>> direct and indirect dependencies don't seem to be anything like that >>>> either. Its limited to pretty much nats.io client, gnatds embedded >>>> server, and a thrift rpc. >>>> >>>> It seems so random that I doubt I could get a reproducible crash. So I >>>> can really only try testing this on go 1.11 instead to see if any of the GC >>>> work in 1.12 causes this. >>>> >>>> >>>>> >>>>> >>>>> On Monday, 29 April 2019 21:59:34 UTC-7, Justin Israel wrote: >>>>>> >>>>>> >>>>>> On Thursday, November 29, 2018 at 6:22:56 PM UTC+13, Justin Israel >>>>>> wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Thu, Nov 29, 2018 at 6:20 PM Justin Israel <justin...@gmail.com> >>>>>>> wrote: >>>>>>> >>>>>>>> On Thu, Nov 29, 2018 at 5:32 PM Ian Lance Taylor <ia...@golang.org> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> On Wed, Nov 28, 2018 at 7:18 PM Justin Israel <justin...@gmail.com> >>>>>>>>> wrote: >>>>>>>>> > >>>>>>>>> > I've got a service that I have been testing quite a lot over the >>>>>>>>> last few days. Only after I handed it off for some testing to a >>>>>>>>> colleague, >>>>>>>>> was he able to produce a SIGBUS panic that I had not seen before: >>>>>>>>> > >>>>>>>>> > go 1.11.2 linux/amd64 >>>>>>>>> > >>>>>>>>> > The service does set up its own SIGINT/SIGTERM handling via the >>>>>>>>> typical siginal.Notify approach. The nature of the program is that it >>>>>>>>> listens on nats.io message queues, and receives requests to run >>>>>>>>> tasks as sub-processes. My tests have been running between 40-200 of >>>>>>>>> these >>>>>>>>> instances over the course of a few days. But this panic occurred on a >>>>>>>>> completely different machine that those I had been testing... >>>>>>>>> > >>>>>>>>> > goroutine 1121 [runnable (scan)]: >>>>>>>>> > fatal error: unexpected signal during runtime execution >>>>>>>>> > panic during panic >>>>>>>>> > [signal SIGBUS: bus error code=0x2 addr=0xfa2adc pc=0x451637] >>>>>>>>> > >>>>>>>>> > runtime stack: >>>>>>>>> > runtime.throw(0xcf7fe3, 0x2a) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/panic.go:608 +0x72 >>>>>>>>> > runtime.sigpanic() >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/signal_unix.go:374 +0x2f2 >>>>>>>>> > runtime.gentraceback(0xffffffffffffffff, 0xffffffffffffffff, >>>>>>>>> 0x0, 0xc0004baa80, 0x0, 0x0, 0x64, 0x0, 0x0, 0x0, ...) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/traceback.go:190 +0x377 >>>>>>>>> > runtime.traceback1(0xffffffffffffffff, 0xffffffffffffffff, 0x0, >>>>>>>>> 0xc0004baa80, 0x0) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/traceback.go:728 +0xf3 >>>>>>>>> > runtime.traceback(0xffffffffffffffff, 0xffffffffffffffff, 0x0, >>>>>>>>> 0xc0004baa80) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/traceback.go:682 +0x52 >>>>>>>>> > runtime.tracebackothers(0xc00012e780) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/traceback.go:947 +0x187 >>>>>>>>> > runtime.dopanic_m(0xc00012e780, 0x42dcc2, 0x7f83f6ffc808, 0x1) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/panic.go:805 +0x2aa >>>>>>>>> > runtime.fatalthrow.func1() >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/panic.go:663 +0x5f >>>>>>>>> > runtime.fatalthrow() >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/panic.go:660 +0x57 >>>>>>>>> > runtime.throw(0xcf7fe3, 0x2a) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/panic.go:608 +0x72 >>>>>>>>> > runtime.sigpanic() >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/signal_unix.go:374 +0x2f2 >>>>>>>>> > runtime.gentraceback(0xffffffffffffffff, 0xffffffffffffffff, >>>>>>>>> 0x0, 0xc0004baa80, 0x0, 0x0, 0x7fffffff, 0x7f83f6ffcd00, 0x0, 0x0, >>>>>>>>> ...) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/traceback.go:190 +0x377 >>>>>>>>> > runtime.scanstack(0xc0004baa80, 0xc000031270) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/mgcmark.go:786 +0x15a >>>>>>>>> > runtime.scang(0xc0004baa80, 0xc000031270) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/proc.go:947 +0x218 >>>>>>>>> > runtime.markroot.func1() >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/mgcmark.go:264 +0x6d >>>>>>>>> > runtime.markroot(0xc000031270, 0xc000000047) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/mgcmark.go:245 +0x309 >>>>>>>>> > runtime.gcDrain(0xc000031270, 0x6) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/mgcmark.go:882 +0x117 >>>>>>>>> > runtime.gcBgMarkWorker.func2() >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/mgc.go:1858 +0x13f >>>>>>>>> > runtime.systemstack(0x7f83f7ffeb90) >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/asm_amd64.s:351 +0x66 >>>>>>>>> > runtime.mstart() >>>>>>>>> > /vol/apps/go/1.11.2/src/runtime/proc.go:1229 >>>>>>>>> > >>>>>>>>> > Much appreciated for any insight. >>>>>>>>> >>>>>>>>> Is the problem repeatable? >>>>>>>>> >>>>>>>>> It looks like it crashed while tracing back the stack during >>>>>>>>> garbage >>>>>>>>> collection, but I don't know why since the panic was evidently >>>>>>>>> able to >>>>>>>>> trace back the stack just fine. >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Thanks for the reply. Unfortunately it was rare and never happened >>>>>>>> in my own testing of thousands of runs of this service. The colleague >>>>>>>> that >>>>>>>> saw this crash on one of his workstations was not able to repro it >>>>>>>> after >>>>>>>> attempting another run of the workflow. I wasn't really sure how to >>>>>>>> debug >>>>>>>> this particular crash since it was in the gc and I have seen a "panic >>>>>>>> during panic" before. Thought it might jump out at someone. >>>>>>>> >>>>>>> >>>>>>> Oops. I meant that I *haven't* seen a "panic during panic" before >>>>>>> :-) >>>>>>> >>>>>>> >>>>>>>> >>>>>>>>> Ian >>>>>>>>> >>>>>>>> >>>>>> >>>>>> This is a follow up to the issue of seeing a SIGBUS in my >>>>>> application. While I still don't have a way to reproduce the problem, I >>>>>> have received reports from my users of another similar SIGBUS: >>>>>> >>>>>> unexpected fault address 0x7fdf50 >>>>>> fatal error: fault >>>>>> [signal 0xb code=0x2 addr=0x7fdf50 pc=0x7fdf50] >>>>>> >>>>>> runtime.throw(0xad7840, 0x5) >>>>>> /s/go/1.12.1/src/runtime/panic.go:617 +0x72 fp=0xc000f75aa8 >>>>>> sp=0xc000f75a78 pc=0x444a5e >>>>>> runtime.sigpanic() >>>>>> /s/go/1.12.1/src/runtime/sigpanic_unix.go:387 +0x47e >>>>>> fp=0xc000f75ad8 sp=0xc000f75aa8 pc=0x444a5e >>>>>> >>>>>> project.com/project/obj.(*Server).newPushHandler.func1.1.1(0xc0008ea330, >>>>>> 0x25, 0x0) >>>>>> >>>>>> This is an anonymous inline function closure that was passed to a >>>>>> nats.io client topic subscription. If I am reading this correctly, >>>>>> it seems the address to the anonymous function is suddenly invalid? >>>>>> >>>>>> ie. >>>>>> >>>>>> go func() { >>>>>> ... >>>>>> someChan := make(chan bool, 1) >>>>>> natsConn.Subscribe(topic, func(_ string, typ Type) { >>>>>> ... >>>>>> someChan <- true >>>>>> }) >>>>>> ... >>>>>> }() >>>>>> >>>>>> Could I be triggering a bug based on this anonymous function closure >>>>>> in the goroutine? I can try defining things outside the goroutine, >>>>>> including the function. But honestly without this being a reliable crash >>>>>> I >>>>>> would be fumbling in the dark. >>>>>> >>>>>> Justin >>>>>> >>>>> -- >>>>> You received this message because you are subscribed to a topic in the >>>>> Google Groups "golang-nuts" group. >>>>> To unsubscribe from this topic, visit >>>>> https://groups.google.com/d/topic/golang-nuts/5tIkzXWCK0k/unsubscribe. >>>>> To unsubscribe from this group and all its topics, send an email to >>>>> golan...@googlegroups.com. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> -- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "golang-nuts" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/golang-nuts/5tIkzXWCK0k/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> golan...@googlegroups.com. >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- > You received this message because you are subscribed to a topic in the > Google Groups "golang-nuts" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/golang-nuts/5tIkzXWCK0k/unsubscribe. > To unsubscribe from this group and all its topics, 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. 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