06ee05026b
I noticed a very intermittent test failure where interpret would end up running, but *fail* because a value wasn't present. This should never happen, because the function engine is designed to only call interpret when there has been at least one value produced for every node in the AST. So what is the bug that would produce: interpret error: could not interpret: func value does not yet exist About 20 minutes ago while I was getting to bed, it occurred to me where to look! Out of bed and to the laptop, and after briefly reminding myself of the code, I think I've found the issue. What I think was happening, was that an AST node would produce a value, and send a message on the aggregate channel. This channel is monitored, and every time it receives a message, it checks to ensure that all the values now exist before producing a message for interpret to run. However, this AST node was not the final one to be produced, but before the message was read by the aggregate channel, the last remaining AST node ran and set it's "loaded" state to `true`, but *before* its value was made available for the aggregate channel to read. That channel then occasionally won the race and tried to access a value before it existed, thus causing out intermittent bug. At least I think that's what was going on. Hopefully this patch fixes this, if not, then there's another bug hiding too! And of course, this entire function engine could do with some proper analysis from someone familiar with glitches, back pressure, and FRP parallelism. One particular note was that I used my brain, not some fancy debugging tool to find this. Maybe skilled debuggers can fork lift their tools onto this type of problem, but I haven't those skills! ¯\_(ツ)_/¯
mgmt: next generation config management!
Community:
Come join us in the mgmt community!
| Medium | Link |
|---|---|
| IRC | #mgmtconfig on Freenode |
| @mgmtconfig & #mgmtconfig | |
| Mailing list | mgmtconfig-list@redhat.com |
Status:
Mgmt is a next generation automation tool. It has similarities to other tools in the configuration management space, but has a fast, modern, distributed systems approach. The project contains an engine and a language. Please have a look at an introductory video or blog post.
Mgmt is a fairly new project. It is usable today, but not yet feature complete. With your help you'll be able to influence our design and get us to 1.0 sooner! Interested developers should read the quick start guide.
Documentation:
Please read, enjoy and help improve our documentation!
| Documentation | Additional Notes |
|---|---|
| quick start guide | for mgmt developers |
| frequently asked questions | for everyone |
| general documentation | for everyone |
| language guide | for everyone |
| function guide | for mgmt developers |
| resource guide | for mgmt developers |
| style guide | for mgmt developers |
| godoc API reference | for mgmt developers |
| prometheus guide | for everyone |
| puppet guide | for puppet sysadmins |
| development | for mgmt developers |
Questions:
Please ask in the community! If you have a well phrased question that might benefit others, consider asking it by sending a patch to the FAQ section. I'll merge your question, and a patch with the answer!
Roadmap:
Feel free to grab one of the straightforward #mgmtlove issues if you're a first time contributor to the project or if you're unsure about what to hack on! Please see: TODO.md for a list of upcoming work and TODO items. Please get involved by working on one of these items or by suggesting something else!
Bugs:
Please set the DEBUG constant in main.go
to true, and post the logs when you report the issue.
Bonus points if you provide a shell
or OMV reproducible
test case.
Feel free to read my article on debugging golang programs.
Patches:
We'd love to have your patches! Please send them by email, or as a pull request.
On the web:
Read what people are saying and publishing about mgmt!
Happy hacking!