Graceful shutdown of forked workers in Python and JavaScript running in Docker containers

You might encounter a situation where you want to fork a script during execution. For example if the amount of forks is dependent on user input or another specific situation. I encountered such a situation in which I wanted to put load on a service using multiple concurrent processes. In addition, when running in a docker container, only the process with PID=1 receives a SIGTERM signal. If it has terminated, the worker processes receive a SIGKILL signal and are not allowed a graceful shutdown. In order to do a graceful shutdown of the worker processes, the main process needs to manage them and only exit after the worker processes have terminated gracefully. Why do you want processes to be terminated gracefully? In my case because I store performance data in memory (disk is too slow) and only write the data to disk when the test has completed.

This seems relatively straightforward, but there are some challenges. Also I implemented this in JavaScript running on Node and in Python. Python and JavaScript handle forking differently.

Database releases. How can we make things better?

Releases of Java (technology related) code often are easy. Releases of database code often are not. Why is that? An important difference and cause can be found in that database code tends to be incremental. Being incremental means that a database release is build on top of previous releases. A database release has to be incremental because often a production environment holds data which needs to be preserved. With Java code, the previous releases (EAR, WAR, JAR files and the like) are less important for the present release since usually they are overwritten. Of course Java releases have their own complexities, however often they do not hold data; that is the task of the database. In this blog I will describe some of the common issues and several suggestions to improve (database) releases. Even though I am a developer (with quite some experience in release automation), I tried to also describe the issues system operators are facing and provide suggestions to improve the process.