Make long running tasks short for development

COmpiling the Linux Kernel is a long running task. Oh, sure, you can put -j 32 and it speeds it up tremendously. But it still is a long running task. And by that, I mean it fits the following definition:

A Long Running task is one that takes so long that you start doing something else before it is done.


If you are familiar with the concept of Flow, then a long running task is one that breaks the flow.

It seems that these kind of “flow Blockers” are common in my line of work. I tend to work on distributed systems, and network based workflows are usually long running tasks. Things like:

  • Ansible Playbooks that allocate a bunch a virtual machines before install software on them.
  • Software install process like ipa-server install
  • Automatically build, install, and test the Linux Kernel

This last one is the thing I am working on now.

The funny part is that I don’t have to do the hard work of making the Kernel compile. This is the responsibility of the team I am building this for, and I can assume that it works OK. This assumption will allow me to skip actually building the Kernel for the majority of my effort.

What do I need to do? I need to write a small yaml file that gitlab will use to kick off a CI/CD Pipeline. This file is a fairly thin wrapper around a bash script (similar pattern to RPM spec files, Ansible, and so forth) that will be executed on the remote system when triggered by a new or modified merge-request. This code needs to install a bunch of RPMs via dnf, kick off the kernel build, and then upload the artifacts to an object store. Right now, I am working on that last bit.

If I wait for the Linux Kernel to build, each iteration of code changes in my development cycle will take more than an hour. Thus, I want to put off actually building the Kernel until I know the rest of the tasks work. All I need to do is test that something gets uploaded, I don’t really care what that thing is. So I comment out the make and replace it with the simplest command I can think of to create a file:

 #- make -j 16 rpm-pkg mkdir ./artifacts
 - touch  ./artifacts/test.test

There is actually a bunch of stuff I comment out including the part where I install packages from dnf. If I know that the code is working, there is little benefit to running it during the debug cycle for the upload stage.
However, I only want to comment out lines, not remove, Why? Because the code needs to be put back in to place in the final assembly, and I don’t want to have to debug the long running process.

With the actual build elided from my process, I can test the system by submiting a no-op merge request and see that gitlab triggers the runner to run my code. My round trip is now about a minute, short enough that I can keep myself on task.


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