[vbox-dev] Parallel Usage of VBoxManage

[Klaus Espenlaub]

Martin,

On 12.03.2015 10:09, Martin Potthast wrote:
> Hi everyone,
>
> I am doing many calls to VBoxManage on a host running 30 headless VMs,
> sometimes in parallel. The calls mostly include startvm, controlvm
> poweroff, clonevm --snapshot, unregistervm --delete, and snapshot
> delete.
>
> Occasionally, a call hangs indefinitely or fails. I have not found a
> way to reproduce this in controlled manner, though.

Which VirtualBox version? What host OS?

The past releases contained several fixes which can resolve hangs.

Issues with hangs usually can be investigated by analyzing the state of 
VBoxSVC and the affected VBoxManage processes. Sometimes the VM process 
state is needed, too.

Not sure about what you mean by "fails". Could be that you issue 
commands to a VM which currently is changing its state for some other 
reason already, and then API calls can fail.

> Since it works most of the time, I am wondering how I can solve the
> problem. I'm thinking about putting each VM in a different user on the
> same host. Do you think this might solve the problem?

It will help if it's a cross-VM problem. Otherwise it will just need 
more resources (more VBoxSVC instances, ...).

> Or put another way, can there be cross-talk between instances of VBox
> running under different users, or are these instances completely
> separated?

There is a common code for actually executing the VMs, but from the 
symptoms I doubt this is the root cause. Smells more like an API level 
problem. See above.

I would prefer to investigate and properly fix the issue. Going for 
workaround means the bug will stay there until someone accidentally runs 
into it and does the investigation.

Klaus

> Any help with this issue is highly appreciated.
>
> Best,
> Martin