Cross posted on mathematica.stackexchange

TLDR

There is a pool of kernels/sessions available for each user, you don't have control over the pool, only over specific kernel you currently evaluate in. Re-upload of a package should be followed by quit on every kernel where previous version of a package was used. I failed to find tools for that.

Background

I'm developing a package which I want to deploy to my Wolfram Public Cloud's account and I want a set of APIFunctions/FormFunctions/etc to be able to use it.

• PacletManager has limited functionality so I'm just uploading package's archive and extracting it to WPC's $UserBaseDirectory / Applications /.

• APIFunctions and friends have form:

   APIFunction[{}, (Needs["TestPackage`"];Symbol["TestPackage`api2"][...]) &]
  

I use Symbol because otherwise TestPackage` definitions are uploaded and I want to avoid that. There should be one code source, the package in $UserBaseDirectory.

Problem

The problem is that kernels' management on WPC is a closed black box. If you call the api twice, each time it uses one of the kernels in the pool. It also applies to CloudEvaluate etc.

$UserBaseDirectory is shared but Get will find the current version ony for current kernel.

If in another kernel TestPackage` was loaded earlier, Needs will not load the current version there :-/ I don't wan't to Get in my APIFunctions, a proper way is to call Needs.

And there is no way to Quit every available kernel.

Example

is worth of 10^3 words:

First we will mimic a package upload, 10 times. So it was uploaded, something was fixed it was uploaded again etc:

packageTemplate = StringTemplate["
   BeginPackage[\"TestPackage<*\"`\"*>\"];
   myValue = \"``\"
   EndPackage[];
"];

Do[
   CloudExport[packageTemplate@RandomReal[], "Text", "TestPackage.m"]
 ; CloudEvaluate[
       CopyFile[
           "TestPackage.m"
         , StringRiffle[
               {$UserBaseDirectory, "Applications", "TestPackage.m"}
             , "/"
           ]
         , OverwriteTarget -> True
       ]
     ; Get @ "TestPackage`"
   ]
 , {10}
]

Now let's call code based on the package 25 times:

Table[
    CloudEvaluate[
        Needs["TestPackage`"]
      ; {$SessionID, Symbol["TestPackage`myValue"]}
    ]
 ,  {25}
] // CountBy[Last] // Normal // Column

7 different results, I expect only one variant, from the last deployment.

The question

How to upload a package and clean properly, as we can see Get after the upload only affects one particular kernel/sessopm. CloudEvaluate@Quit[] won't help either.

How to reset them all?

Requirements

 APIFunction[{}, (Get["TestPackage`"];Symbol["TestPackage`api2"][...]) &]

could solve it but if the package contains Protected/Locked symbols you will get a flood of errors. And because of the same reason you can't ClearAll symbols. And obviously you can't Quit in ApiFunction.