dfalling
Elixir Crashes in Virtualbox with monotonic time message
I’m running Elixir/Phoenix in a VirtualBox instance. After a short period of time (typically 5 minutes or so), Elixir quits with this output:
Monotonic time stepped backwards!
Previous time: 2140883699436
Current time: 2140883692221
[os_mon] cpu supervisor port (cpu_sup): Erlang has closed
[os_mon] memory supervisor port (memsup): Erlang has closed
zsh: IOT instruction (core dumped) mix phx.server
I can’t find any sort of erlang crash log. What should I do to troubleshoot this crash? At the time of the crash I have plenty of memory and swap available.
VM OS: Lubuntu 22.04.1 LTS
VM Memory: 2GB
VM Swap: 2GB
Elixir: 1.14.0
Erlang: 25.0.4
Marked As Solved
itopiz
This was indeed an issue with VirtualBox and it has been fixed (#22334 (VM clock goes backwards => fixed in svn) – Oracle VirtualBox). Waiting for a new VirtualBox release now.
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derek-zhou
At its core the BEAM is a preemptive multi-threaded system. So if the clock is funky then the scheduling will not be fair. If the clock warp too much then I guess some GenServer calls could even timeout.
tcoopman
The issue is that your VM turned back in time, which erlang doesn’t like.
After reading a bit more on this, I also found this which says disabling time correction is the solution: Passing erl options to erlc? - #7 by rickard - Questions / Help - Erlang Programming Language Forum - Erlang Forums
Reading the time and correction module in Erlang was not entirely clear, but I think all the time warping is about the erlang monotonic time and not the OS monotonic time.
tcoopman
When searching for virtualbox and monotonic time you find some issues. For example #7915 (Mircosecond timer returns value from the past) – Oracle VirtualBox
It’s a very old issue. Although there might still be issues around?
Last Post!
itopiz
VirtualBox 7.1.8 has been released on April 15 2025 and fixes the issue:
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