- There’s an almost wysiwig editor for mermaid at https://www.mermaidchart.com/play . It’s very convenient and appropriately changes the layout as you draw arrows!

- Notion supports inline mermaid charts in code blocks (with preview!) It’s awesome for putting some architecture diagrams in Eng docs.

Explicit dynamic bindings are better if you need something like this since those are thread local.

  sigterm_handler() {
    make_healthcheck_fail();
    sleep(20);
    stop_web_server();
    exit(0);
  }

That said trying to enforce overhead limits with RSS limits also won’t end well. Java doesn’t make guarantees around max allocated but unused heap space. You need something like this: https://github.com/bazelbuild/bazel/blob/10060cd638027975480... - but I have rarely seen something like that in production.

If you have an actual memory leak in a JVM app what you want is an exception called java.lang.OutOfMemoryError . This means the heap is full and has no space for new objects even after a GC run.

An OOMKilled means the JVM attempted to allocate memory from the OS but the OS doesn't have any memory available. The kernel then immediately kills the process. The problem is that the JVM at the time thinks that _it should be able to allocate memory_ - i.e. it's not trying to garbage collect old objects - it's just calling malloc for some unrelated reason. It never gets a chance to say "man I should clear up some space cause I'm running out". The JVM doesn't know the cgroup memory limit.

So how do you convince the JVM that it really shouldn't be using that much memory? It's...complicated. The big answer is -Xmx but there's a ton more flags that matter (-Xss, -XX:MaxMetaspaceSize, etc). Folks think that -XX:+UseContainerSupport fixes this whole thing, but it doesn't; there's no magic bullet. See https://ihor-mutel.medium.com/tracking-jvm-memory-issues-on-... for a good discussion.

So about an 8% chance. You’re significantly more likely (ie 92% chance) to see _something else_. And that’s _the most_ likely outcome.

So tldr - it’s not so much that “you never see an all tails sequence in practice” - you’re actually unlikely to see any particular sequence. All the probabilities get astonishingly low very quickly.

An example of this might be a dashboard with 20 filters and 20 parameters controlling breakdown dimensions and “assumptions used.” So asking “how did Google ads perform in the last month broken down by age group” is about changing 3-4 preset dropdowns. Parameters are also key here - this way you only expose the knobs that you’ve vetted - not arbitrary SQL.

Obviously this is a hard dashboard to build and requires quite a bit of viz expertise (eg experience with looker or tableau or excel) but the result is 70% of questions do become self service. The other 30% - abandon hope. You will need someone to translate business questions into data questions and that’s a human problem.

If that’s not your interest, I will admit that Postgres array support is far ahead of any of the MySQLs. Most ORMs don’t use it but you can get optimal query prefetching via array subqueries.