Re: [RFC PATCH proxmox-backup 0/2] fix #7756: avoid qmp 'backup' timeout

[Christian Ebner <c.ebner@proxmox.com>]

On 10/26/26 2:46 PM, Christian Ebner wrote:
> During high load due to parallel backups or slow storage backend on
> the PBS, tokio blocking thread pool can become an issue. This is
> because fetching of the previous snapshot manifest and index files
> may be blocked in the blocking queue for a long time, leading to
> exceeded QMP command timeout, especially notable for snapshots with
> large index files.
> 
> These patches optimize the async reader for content fetching and
> draft a possible workaround by fully offloading the file download
> handling to a dedicated thread, not offloading it to tokio's blocking
> thread pool.
> 
> Open question is whether it would make sense to distinguish between
> API endpoints with higher priority and ones with lower priority in
> general, and offload them to high priority and low priority thread
> pools instead of spawning new threads on demand.
> 
> Issue was raised again recently in the enterprise support and several
> times in the community forum [0-2].
> 
> [0] https://forum.proxmox.com/threads/179304/
> [1] https://forum.proxmox.com/threads/183380/
> [2] https://forum.proxmox.com/threads/185679/

For completeness, this related issue which covers reworking the client 
side https://bugzilla.proxmox.com/show_bug.cgi?id=5080