Native / Docker runtime does not reuse variables outside of main function in Golang

[jonee]

Environment details:

• IBM Cloud Functions
• Docker / Native runtime

Steps to reproduce the issue:

1. Create the action with the code below
2. Retrieve the web action and invoke with a post
   ibmcloud fn action get helloGo --url <- returns your url
   curl -X POST -d '{"name":"sfdsfs4 "}' https://us-south.functions.appdomain.cloud/api/v1/xxx/helloGo.json
3. review the logs
   ibmcloud wsk activation logs --last # returns the logs
   notice that variable t0 is never reused. You always see "new t0" in the logs

Provide the expected results and outputs:

That it re uses the variables outside of main like for other runtimes. 

Provide the actual results and outputs:

It does not reuse variables outside of main. This is usually used to reuse db connection.

Additional information you deem important:

• issue happens 100% of the time and should be easy to reproduce

Code for native / docker runtime
save as main.go
GOOS=linux GOARCH=amd64 go build -o exec
zip exec.zip exec
ibmcloud wsk action update helloGo --native exec.zip
ibmcloud fn action get helloGo --url <- returns your url
curl -X POST -d '{"name":"sfdsfs4 "}' https://us-south.functions.appdomain.cloud/api/v1//helloGo.json
ibmcloud wsk activation logs --last # returns the logs

package main

import (
    "fmt"
    "log"
    "os"
    "time"
    "encoding/json"
)
var t0 time.Time

func main() {
    log.Println("os.Args")
    log.Println(os.Args)

    if t0.IsZero() {
		t0 = time.Now()
		log.Println("new t0")
	} else {
		log.Println("re used t0")
    }

    msg := map[string]string{"body": ("Hello!")}
    res, _ := json.Marshal(msg)
    fmt.Println(string(res))
}

[jonee]

Or is this a known limitation of this runtime that uses binary?

[rabbah]

The golang OpenWhisk runtime does reuse variables. You can try a properly working version here:
https://apigcp.nimbella.io/api/v1/web/playground/user463062/y

and see the code here:
https://apigcp.nimbella.io/api/v1/web/playground/default/showCode/user463062/y

[jonee]

I am aware that the golang runtime does reuse variables outside of main function.

But the native / docker does not. So probably if you use another programming language say Rust then compile statically then you could expect the same behaviour.

I would appreciate a confirmation that this is a limitation of the runtime and not a bug. Thanks!

[rabbah]

Ah sorry - I missed the "native" qualification. In this model, each invocation is a new process, so there won't be any reuse. It's possible to implement an alternate protocol though but that involves using file descriptors (this is referred to as the action loop).

[rabbah]

Reference for the action loop: https://github.com/apache/openwhisk/blob/master/docs/actions-actionloop.md.

[jonee]

Thanks @rabbah !

When you have time can you please take a look at the other bug that I filed? #5043