Best (simplest) way to share data (Posting On Python-List Prohibited)

[Chris Green]

Lawrence D'Oliveiro <ldo at nz.invalid> wrote:
> On Sat, 6 Jul 2024 08:28:41 +0100, Chris Green wrote:
> 
> > One fairly obvious way is to have single process/script which reads the
> > A2D values continuously and writes them to a file.  All other scripts
> > then read from the file as needed, a simple file lock can then be used
> > to prevent simultaneous access (well, simultaneous access when the
> > writing process is writing).
> 
> The thing with a file is, it persists even when the collector process is 
> not running. Do you want data that persists when the collector process is 
> not running?
> 
> Is this a history of values, or just a snapshot of current values? A 
> history of values could be written to a database. Databases provide their 
> own transactions and interlocking to prevent readers from reading partial 
> updates.
> 
There's a separate (crontab driven) process that writes the history to
a sqlite3 database,


> If it’s a snapshot of current values, that does not persist when the 
> collector process is not running, then why not just keep the data in the 
> memory of the collector process, and have it concurrently listen on a 
> socket for connections from readers requesting a copy of the current data?

That's exactly the sort of solution I was wondering about.  Is there a
ready made module/library for handling this sort of thing?  Basically
it will just be a string of a few tens of characters that would be
kept up to date by one process and asked for by all the others.

-- 
Chris Green
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