Allow the server to run with multiple workers

JavaScript is single-threaded, but Node.js can run an HTTP server with multiple workers such that different HTTP requests are handled independently with different threads.

In order to realize this, we need to:

• write and test code to fire up multiple workers at start-up (https://nodejs.org/api/cluster.html)
  • when running in multi-worker mode, log a warning that we are and that there should be no single-threaded components
• set a configuration parameter plus command-line switch for the number of workers
• perhaps provide a global mechanism for single-threaded components that they can register for safety reasons
• e.g., an ensureSingleThreaded() which throws if not https://nodejs.org/api/cluster.html#cluster_cluster_ismaster (and perhaps also if not not https://nodejs.org/api/worker_threads.html#worker_threads_worker_ismainthread)
• ensure there are multi-threaded alternatives for every currently single-threaded component
  • seems to only involve locking: https://github.com/solid/community-server/issues/309

[RubenVerborgh]

Would you have some example of this? I can’t really seem to find what you are saying.

If we do add the worker metadata to the logger at construction time, then it can be easy to filter it somewhere down the line. Winston log calls accept a third meta argument that can be an arbitrary object, so we can store in there what we want and use it for filtering later: https://github.com/winstonjs/winston#filtering-info-objects

[RubenVerborgh]

Perfect, love it.