Re: [pdm-devel] [PATCH proxmox-datacenter-manager v3 0/6] remote task cache fetching task / better cache backend

From: Wolfgang Bumiller <w.bumiller@proxmox.com>
To: Thomas Lamprecht <t.lamprecht@proxmox.com>
Cc: Proxmox Datacenter Manager development discussion
	<pdm-devel@lists.proxmox.com>
Subject: Re: [pdm-devel] [PATCH proxmox-datacenter-manager v3 0/6] remote task cache fetching task / better cache backend
Date: Fri, 18 Apr 2025 09:12:36 +0200	[thread overview]
Message-ID: <b63uc4pklvib5rxdiga3nuopxohiqxpebtakbjl6riqseeognw@6ur22hzflvby> (raw)
In-Reply-To: <31497f93-68ac-4bfb-8f42-636edce9cf9f@proxmox.com>

On Thu, Apr 17, 2025 at 05:31:56PM +0200, Thomas Lamprecht wrote:
> Am 17.04.25 um 15:22 schrieb Lukas Wagner:
> > Benchmarking was done using the 'fake-remote' feature. There were 100
> > remotes, 10 PVE nodes per remote. The task cache contained
> > about 1.5 million tasks.
> >                                                before        after
> > list of active tasks (*):                     ~1.3s          ~30µs
> > list of 500 tasks, offset 0 (**):             ~1.3s         ~500µs
> > list of 500 tasks, offset 1 million (***):    ~1.3s         ~200ms
> > Size on disk:                                 ~500MB        ~200MB
> > 
> > (*):  Requested by the UI every 3s
> > (**): Requested by the UI when visiting Remotes > Tasks
> > (***): E.g. when scrolling towars the bottom of 'Remotes > Tasks'
> 
> Did you regenerate these for the current revision? Just out of interest
> whether there is any measurable effect of Wolfgangs proposed changes.
> 
> And FWIW, I'd like to encode these also in the commit message, albeit
> with the lore links that b4 adds it's less of a problem, but IMO would
> still not really hurt to do. Depending on your answer on the actuality
> of above data I could amend that or newly provided measurements into
> the commit message on applying though, so definitively no need for a v+1
> just for that.
> 
> > 
> > In the old implementation, the archive file was *always* fully deserialized
> > and loaded into RAM, this is the reason why the time needed is pretty
> > idential for all scenarios.
> > The new implementation reads the archive files only line by line,
> > and only 500 tasks were loaded into RAM at the same time. The higher the offset,
> > the more archive lines/files we have to scan, which increases the
> > time needed to access the data. The tasks are sorted descending
> > by starttime, as a result the requests get slower the further you
> > go back in history.
> > 
> > The 'before' times do NOT include the time needed for actually fetching
> > the task data.
> > 
> > This series was preseded by [1], however almost all of the code has changes, which
> > is the reason why I send this as a new series.
> > 
> > [1] https://lore.proxmox.com/pdm-devel/20250128122520.167796-1-l.wagner@proxmox.com/
> > 
> > Changes since v2:
> >   - Change locking approach as suggested by Wolfgang
> >   - Incorporated feedback from Wolfang
> >      - see patch notes for details
> >   - Added some .context/.with_context for better error messages
> > 
> 
> Looks alright to me now, if Wolfgang sees nothing of w.r.t. the changes
> since the last version I'd apply this series tomorrow.

Mostly LGTM, just minor issues. (A bunch of `pub`s to drop, one of which
is important in patch 3.)

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