fuse | rr | |
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2 | 102 | |
493 | 8,665 | |
- | 1.1% | |
0.0 | 9.6 | |
about 2 years ago | 7 days ago | |
Erlang | C++ | |
MIT License | GNU General Public License v3.0 or later |
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For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
fuse
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When "letting it crash" is not enough
Indeed. I do wish there were a few more "extras" in OTP, because "let it crash" needs some more details in some circumstances.
For instance if you have a system with a user interface and some various components, like say, a database, and the database becomes unavailable, you don't want the entire system to crash. You want it to display an error message to the user and maybe go into some kind of diagnostic mode or other "things are not normal" state.
Something like https://github.com/jlouis/fuse is one approach.
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Elixir for Cynical Curmudgeons
> If you configure it well (the defaults are not always optimal) you can have your invisible mesh of services survive extended outages of the 3rd party APIs it depends on.
This is something that annoyed me a bit with OTP. The basic strategies aren't really enough for that, so you need something like https://github.com/jlouis/fuse
I wrote something like that myself, but it hasn't seen a ton of use: https://github.com/davidw/hardcore
rr
- rr: Lightweight Recording and Deterministic Debugging
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Hermit is a hermetic and reproducible sandbox for running programs
I think this tool must share a lot techniques and use cases with rr. I wonder how it compares in various aspects.
https://rr-project.org/
rr "sells" as a "reversible debugger", but it obviously needs the determinism for its record and replay to work, and AFAIK it employs similar techniques regarding system call interception and serializing on a single CPU. The reversible debugger aspect is built on periodic snapshotting on top of it and replaying from those snapshots, AFAIK. They package it in a gdb compatible interface.
Hermit also lists record/replay as a motivation, although it doesn't list reversible debugging in general.
- Rr: Lightweight Recording and Deterministic Debugging
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Deep Bug
Interesting. Perhaps you can inspect the disassembly of the function in question when using Graal and HotSpot. It is likely related to that.
Another debugging technique we use for heisenbugs is to see if `rr` [1] can reproduce it. If it can then that's great as it allows you to go back in time to debug what may have caused the bug. But `rr` is often not great for concurrency bugs since it emulates a single-core machine. Though debugging a VM is generally a nightmare. What we desperately need is a debugger that can debug both the VM and the language running on top of it. Usually it's one or the other.
> In general I’d argue you haven’t fixed a bug unless you understand why it happened and why your fix worked, which makes this frustrating, since every indication is that the bug exists within proprietary code that is out of my reach.
Were you using Oracle GraalVM? GraalVM community edition is open source, so maybe it's worth checking if it is reproducible in that.
[1]: https://github.com/rr-debugger/rr
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So you think you want to write a deterministic hypervisor?
https://rr-project.org/ had the same problem. They use the retired conditional branch counter instead of instruction counter, and then instruction steeping until at the correct address.
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Is Something Bugging You?
That'll work great for your Distributed QSort Incorporated startup, where the only product is a sorting algorithm.
Formal software verification is very useful. But what can be usefully formalized is rather limited, and what can be formalized correctly in practice is even more limited. That means you need to restrict your scope to something sane and useful. As a result, in the real world running thousands of tests is practically useful. (Well, it depends on what those tests are; it's easy to write 1000s of tests that either test the same thing, or only test the things that will pass and not the things that would fail.) They are especially useful if running in a mode where the unexpected happens often, as it sounds like this system can do. (It's reminiscent of rr's chaos mode -- https://rr-project.org/ linking to https://robert.ocallahan.org/2016/02/introducing-rr-chaos-mo... )
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When "letting it crash" is not enough
The approach of check-pointing computation such that it is resumable and restartable sounds similar to a time-traveling debugger, like rr or WinDbg:
https://rr-project.org/
https://learn.microsoft.com/windows-hardware/drivers/debugge...
- When I got started I debugged using printf() today I debug with print()
- Rr: Record and Replay Debugger – Reverse Debugger
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OpenBSD KDE Plasma Desktop
https://github.com/rr-debugger/rr?tab=readme-ov-file#system-...
What are some alternatives?
lz4 - LZ4 bindings for Erlang
CodeLLDB - A native debugger extension for VSCode based on LLDB
trie - Erlang Trie Implementation
rrweb - record and replay the web
fnv - Pure Elixir implementation of Fowler–Noll–Vo hash functions
gef - GEF (GDB Enhanced Features) - a modern experience for GDB with advanced debugging capabilities for exploit devs & reverse engineers on Linux
red_black_tree - Red-black tree implementation for Elixir.
Module Linker - browse modules by clicking directly on "import" statements on GitHub
cuckoo - :bird: Cuckoo Filters in Elixir
nbdev - Create delightful software with Jupyter Notebooks
graphmath - An Elixir library for performing 2D and 3D mathematics.
clog-cli - Generate beautiful changelogs from your Git commit history