Re: plugin reentrant?

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

On June 17, 2026 9:45 pm, Anthony Galica wrote:
> Hi Everyone,
> 
> Is a proxmox plugin reentrant in that will it simultaneously send two or more requests to the same instance of the running script?

There can be more than one *process* calling into storage plugin perl
code at the same time - API requests are processed concurrently,
including long-running tasks executed in their own worker process, and
CLI tools can also call into plugin code via PVE::Storage.

For some code paths, there will be a mutual exclusion mechanism in
effect via pmxcfs cluster-wide locking for shared storages, and
node-local locking for local storages.

Those mostly cover code paths related to allocating or freeing volumes.

> Does the answer differ for the same storage pool vs. different storage pools?

Currently, the locking done by PVE is per storage plugin instance (which
is normally one pool/export/directory/.. ). We have discussed allowing
storage plugins to mark themselves as not requiring such a coarse lock,
in which case we would instead lock the (storage plugin instance, VMID)
tuple - but that is not yet implemented.

If you have different locking requirements, you can of course implement
your own locking inside your plugin on top of what PVE does - but please
be careful to not cause accidental deadlocks.

Hope this helps - please reach out if you have more questions!
Fabian

P.s. if you are developing your own custom storage plugin, we'd be
interested to know about it!