Do you use the Dockerfile in the repo?
Yesterday I had a similar issue, rebuilt my docker image, but still had the
same issue.
Eventually, I deleted my docker image and built a fresh new image, which
fixed the issue.
I guess Docker build uses some cache and maybe it doesn't load the fresh
tip go every time it builds.

2014-12-19 9:50 GMT-05:00 Hunter Leath notifications@github.com:

What version of go are you running?

devel, definitely after bee8ae1
bee8ae1
.

What OS and ARCH?

Compiling for Android/Arm.

What did you do?

Create a go program that looks like this:

func Run(port int) {
panic("Hello, world.")
}

What did you expect to happen?

The program exits with "Hello, world." printed to the log (viewable in
logcat).

What happened?

Logcat reports nothing, as below:

I/Go ( 3286): app.Run
I/go/Seq ( 3286): loaded go/Seq
I/Go ( 3286): Runtime started
I/Zygote ( 196): Process 3286 exited cleanly (2)
I/ActivityManager( 530): Process com.getmelange.melange (pid 3286) has died

Then restarts the application multiple times.

—
Reply to this email directly or view it on GitHub
#9398.

__

Certainly. I've rebuilt a couple of times with --no-cache to no avail, still nothing in the logcat. Could this have something to do with Lollipop? Although I did not have root, running cat /dev/log/main in adb shell returns No such file or directory..

Additionally, I attempted to work around this issue by adding

defer func() {
    fmt.Println("Hello, world.")
    if r := recover(); r != nil {
        fmt.Println("Golang Panic:", r)
    }
}()

To the top of my function, to no avail. Strangely, still nothing prints out at all.

Quickest way to test that there isn't something wrong with your go installation is to run:

docker run mobile /bin/bash -c 'ls /go/src/runtime/print1*'

If you are synced after the printing CL, you should see

/go/src/runtime/print1.go
/go/src/runtime/print1_write.go
/go/src/runtime/print1_write_android.go

Other than that, you can also try adding

log.Print("test message")

above your panic. The Go log package has an entirely different set of hooks for printing output.

Also, I presume there is more to your Go program than the snippet you pasted. Could you show us the rest of your main function?

So, two interesting developments. The original problem that had me going down this direction was fixed by simply go get -u golang.org/x/mobile since I hadn't done that in a while. Turns out it had to do with returning nil as error.

My main function is something like this with the panic. Since I commented out the other code, I assume this is the important part.

func Run(port int, dataDir string, version string, platform string) error {
   panic("Hello, world.")
   return nil
}

Updating the mobile repository certainly fixed the issue with defer-recover, and it now prints panics to stdout. The bare panic, however, doesn't print to logcat. I have confirmed that print1_write_android.go exists.

Additionally, log and fmt are working normally.

My attempt to replicate this failed. Could you provide a complete small program that demonstrates the problem?

It's very likely that I'm just setup incorrectly somehow. If you are unable to reproduce it using a Lollipop device, then I wouldn't worry about it. The code I was trying it with did, in fact, just have a panic in the Run(.) function.

I don't know what's Run(.) function, but based on the log from your first report (triggering go/Seq logs), I guess the following modification to example/libhello/hi/hi.go is something similar to what you have, right? If so, I will test it with a Lollipop device later today.

diff --git a/example/libhello/hi/hi.go b/example/libhello/hi/hi.go
index a1e868b..cf3ec23 100644
--- a/example/libhello/hi/hi.go
+++ b/example/libhello/hi/hi.go
@@ -4,5 +4,6 @@ package hi
import "fmt"

func Hello(name string) {

•   panic("End of the World...")
  fmt.Printf("Hello, %s!\n", name)
  
  }

FYI adb logcat from 4.4.4 nexus 7: https://gist.github.com/hyangah/0b1225eb3b164096ef87 It includes the panic log.

That would effectively sum up what I was attempting. Do let me know what happens with the Lollipop device, and feel free to close if everything works correctly.

I could reproduce the problem with Nexus 7 running android version 5.0.1.
The same apk still produces the panic log in android 4.4.4.

Based on the recent ndk's logging (https://android.googlesource.com/platform/system/core/+/master/liblog/logd_write.c), I guess logs need to be sent through /dev/socket/logdw (unix domain socket).

The runtime at tip directly writes logs or print messages to /dev/log/main (https://go.googlesource.com/go/+/master/src/runtime/print1_write_android.go)
But /dev/log/... are no longer accessible(?) or used in android-L. Is it possible to use ndk's __android_log_write from the runtime package? __android_log_write handles emulator environment too.

Otherwise, we need to make runtime use /dev/socket/logdw. I don't know android enough to know if it's backwards compatible.