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Runtime

  • in Runtime
  • 7 min read

Pony’s Arena Allocator

Here’s how it was. We’d been running stress tests on the TCP system in ponyc every day for a really long time. Those tests hadn’t failed in forever. There’s two ways you can look at “no tests are failing.” Either your system is rock solid or your tests aren’t covering enough of the codebase. I’d long felt that the lack of stress test failures was the result of “tests aren’t good enough.”

A few months back, I did something about that. I took the TCP stress tests that did the same thing on every run and added some “swarm testing goodness” — randomizing what they were doing and how they were being run, from run to run. A lot more code was getting exercised, and out popped a bunch of bugs.

This post is about one of those “bugs.”

  • in Runtime
  • 6 min read

Improving Runtime Test Coverage

Pony’s runtime has a set of stress tests. They run in CI, each one a program that exercises the runtime over and over for an extended period of time: one passes messages between actors without a break, another opens and closes network connections again and again, sending data back and forth. The idea is that the more you push on a part of the runtime you think is bug-prone, and the longer you keep at it, the more likely you are to shake out a bug that only turns up once in a while. For the runtime, bug-prone means “susceptible to concurrency issues”. And we hammer away at those areas as much as we can. Or try to anyway. That was the idea.