Does every Go program fail in this was, or just the go tool itself? For example, you should be able to use the go tool outside of a jail to build a simple hello, world program. Does that program fail when run in a jail?

What kind of processor are you running on?

I actually don't see how that ktrace output is possible. The Go runtime only ever passes 0xf and 0x10 to _umtx_op. I don't know where the 0x11 is coming from.

Is the userland in your jail in sync with your kernel?

The architecture is amd64; the CPU is an Intel Core i5 750.
Both the userland and the base system and the jail are 10.2-RELEASE-p13.

I tried with a simple hello world program.

• Building it out of the jail works. Running the generated executable in the jail works.
• Building it in the jail results in the go runtime getting stuck the same way.

Finally I tried a hello world program using the C package:

package main

// #include <stdio.h>
//
// static void helloWorld() {
//     printf("hello world\n");
// }
import "C"

func main() {
        C.helloWorld()
}

Building it out of the jail, then running it in the jail results in it getting stuck.
Our software also uses C, and also gets stuck in the same situation.
Does the go runtime use C ? If yes, there could be something wrong with C when running in a jail.

_umtx_op seems to be pthread-related, and afaik, cgo uses pthreads. This would make sense.

The Go runtime itself does not use C. However, many Go programs do use C. Go makes system calls directly, including to _umtx_op. _umtx_op is related to threads. If the jail does not support threads, then no substantial Go program is going to work inside it.

There is afaik nothing in jails that prevent using threads in any way. I already ran multithreaded applications in jails without any problem.

However a quick Google search shows that there are various people having this kind of problems with applications using pthreads. I'm not sure how to fix this problem.

Thanks. I'm going to close this issue because I don't think there is anything we can do on the Go side to fix it. Please reopen if there is something we can change in Go to make it work.