[pve-devel] [PATCH manager 1/4] API2Tools: rrd: remove O(n^2) lookup for keys

[Aaron Lauterer]

On  2025-09-05  14:06, Dominik Csapak wrote:
> the idea was that we get any of the 'new' versions on lookup, but that
> lead to iterating through possibly all keys. Since that was called for
> each resource in e.g. /cluster/resources api call, the runtime was
> O(n^2) for the number of resources.
> 
> To avoid that, simply look up the currently only valid key here which
> makes this lookup much cheaper.
> 
> In my test setup with ~10000 guests, it reduces the time for a call
> to /cluster/resources from ~22s to ~400ms
> 
> Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
> ---
> NOTE: this is only a workaround and Aaron is working to making this
> whole part unnecessary, but for now i think this is a good stop-gap
> 
>   PVE/API2Tools.pm | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/PVE/API2Tools.pm b/PVE/API2Tools.pm
> index abe73fa2..863f5f55 100644
> --- a/PVE/API2Tools.pm
> +++ b/PVE/API2Tools.pm
> @@ -52,10 +52,9 @@ sub get_rrd_key {
>           return "pve2.3-${type}/${id}";
>       }
>   
> -    # if no old key has been found, we expect on in the newer format: pve-{type}-{version}/{id}
> -    # We accept all new versions, as the expectation is that they are only allowed to add new colums as non-breaking change
> -    for my $k (keys %$rrd) {
> -        return $k if $k =~ m/^pve-\Q${type}\E-\d\d?.\d\/\Q${id}\E$/;
> +    my $key = "pve-${type}-9.0/${id}";
> +    if (defined($rrd->{$key})) {
> +        return $key;

Have you tested this in a mixed PVE8 + PVE9 cluster? This might break it 
and we might have to keep the dynamic checking around.

I don't have too much time right now. But I think this would break a 
mixed version situation, e.g. during a cluster upgrade, where we receive 
both keys, pve2-... and pve-...-9.0 ones.

>       }
>   }
>