CC @thanm.

Thanks for the report.

If you could please post a complete example, that would be helpful. In particular, does your example program invoke os.Exit() when it terminates?

does your example program invoke os.Exit() when it terminates?

No, it can't. The program loads the Go shared library is a C++ program, so it won't invoke os.Exit() when it terminates.

If you could please post a complete example, that would be helpful.

It is a Go plugin running inside Envoy: https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/golang_filter.html#golang.

It would require knowledge about Envoy (a network proxy) to run the example. I am glad to give you help if you need.

No, it can't. The program loads the Go shared library is a C++ program, so it won't invoke os.Exit() when it terminates.

Thanks for that.

Given that the Go code is running as a plugin of some sort and is only invoked at the behest of the main process, and isn't being notified when the program terminates, how exactly would you imagine it would be possible to write out coverage counters?

Unless the Go runtime within the plugin has some idea that the program is complete, it doesn't seem as though there's much the runtime can do. I think this is a case where it needs a bit of help from the main program, would you not agree?

No, it can't. The program loads the Go shared library is a C++ program, so it won't invoke os.Exit() when it terminates.

Thanks for that.

Given that the Go code is running as a plugin of some sort and is only invoked at the behest of the main process, and isn't being notified when the program terminates, how exactly would you imagine it would be possible to write out coverage counters?

Unless the Go runtime within the plugin has some idea that the program is complete, it doesn't seem as though there's much the runtime can do. I think this is a case where it needs a bit of help from the main program, would you not agree?

Thanks for your reply.
Is it possible that Go can register something like atexit or add hook to dlclose, so that when the program is gone, the Go code can be noticed and flush the counter?

@spacewander I have the same problem but in my case it does not work properly even with your work around.

in Makefile

instrumented:
GO111MODULE=off go build -cover -covermode=atomic -o lib_um.so -buildmode=c-shared -ldflags="-s -w" ../src/auth.go
gcc -ftest-coverage -fprofile-arcs -shared -o pam.so -I . -DPAM -fPIC ../src/go_auth.c -lcrypt -lcurl -lpthread -ldl -lpam -L. -lum
install:
sudo cp pam.so /usr/lib64/security/
sudo install -m 0755 libzts_um.so /lib64 ; sudo ldconfig

and in the code i have added

    import (
            "runtime/coverage"
    )

and before the main function returns

    writeCoverageData()
    return pamSuccess
	
    func writeCoverageData() {
        coverageFile := "/tmp/auth.go_coverage.out"
        file, err := os.Create(coverageFile)
        if err != nil {
	        panic(err)
        }
        defer file.Close()
        if err := coverage.WriteCounters(file); err != nil {
	        panic(err)
        }
    }		

after successful ssh login (this is a PAM module) I get this file which cannot be read

bash-4.4# go tool cover -func=/tmp/auth.go_coverage.out
cover: bad mode line: cwm����tQ�-��f
bash-4.4#
bash-4.4#
bash-4.4# cat /tmp/auth.go_coverage.out
cwm����tQ�-��f
��@
argc2argv0sshd: user5 [priv]argv1GOOSlinuxGOARCHamd64Rcwmbash-4.4#

This workaround is done by flushing the coverage manually at the proper time. I know nothing about PAM, maybe because it doesn't flush the coverage at the right moment.

@spacewander Hello, I want to manually export coverage data during program execution instead of waiting the program terminates. I also called the coverage.WriteCounters method to output a binary file, but the file cannot be parsed correctly. So I want to know how you manually output coverage and read coverage files. Can you share the code? Thank you very much

I call https://github.com/mosn/htnn/blob/855823f2e50e6c2cc53568fe43be1a17dcd904df/api/plugins/tests/integration/dataplane/plugins.go#L55 at the end of each TestXXX.

I call https://github.com/mosn/htnn/blob/855823f2e50e6c2cc53568fe43be1a17dcd904df/api/plugins/tests/integration/dataplane/plugins.go#L55 at the end of each TestXXX.

Thanks, It's cool