Hi Thanks for your suggestions. This freeze happens to coincide with a larger number of cgo calls which in turn most likely do blocking read/write from sockets. How are those treated by the scheduler?
I am not doing anything FUSE related, nor do I have assembly code. The only "interesting" stuff is the use of a c library - librados. In the goroutine dump from SIGQUIT, some stacks are followed by register dumps. Are those the only ones currently running? All of those are in runtime: 16 are in runtime.futex, 2 are in runtime.notetsleepg and one in runtime.gopark, which would make it seem like it was not an un-preemptable tight loop, but I am not sure how to parse the SIGQUIT output. Thanks Michael > I don't know what is happening with your program. > > This kind of thing can happen if you have a goroutine that is running > in a tight loop with no function calls or memory allocations. The > current Go scheduler is non-preemptive, meaning that nothing will stop > that loop. If that loop occurs while holding a lock, it could block > the entire rest of the program from running. However, you would see > this in the stack trace. This problem with the current scheduler is > https://golang.org/issue/10958. > > This kind of thing can happen if you are using an in-process FUSE file > system implemented by goroutines in your program. The Go runtime > believes that some system calls, such as pipe or socket, never block. > If you have somehow set things up so that those system calls enter > your FUSE file system and depend on some other goroutine running, it > is possible that that goroutine will never be scheduled. I don't know > of any bugs like this at present but they have existed in the past. > Of course if you aren't using a FUSE file system then this is not the > problem. > > This kind of thing can happen if you use assembler code to do a > blocking operation, or if you use syscall.Rawsyscall to call a system > call that blocks. That can confuse the scheduler and lead to a > deadlock. Don't do that. > > None of these are likely, but you asked for suggestions, and that's > what I've come up with. > > 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.
