[bug#45018] [PATCH 0/6] Process and connection reuse for substitutions

["Ludovic Courtès" <ludo@gnu.org>]

[-- Attachment #1: Type: text/plain, Size: 452 bytes --]

Ludovic Courtès <ludo@gnu.org> skribis:

> The attached patches optimize substitute downloads by: (1) keeping
> a single ‘guix substitute’ process for all the substitutes (instead
> of respawning a new one each time a store item is substituted), and
> (2) reusing connections to substitute servers in between substitutions.

As an illustration of what happens at the process level, here’s the perf
timechart in the current situation:


[-- Attachment #2: substitute-chart-one-process-per-substitute.png --]
[-- Type: image/png, Size: 101154 bytes --]

[-- Attachment #3: Type: text/plain, Size: 56 bytes --]


Here’s the timeline once we’re using an agent:


[-- Attachment #4: substitute-chart-agent.png --]
[-- Type: image/png, Size: 55081 bytes --]

[-- Attachment #5: Type: text/plain, Size: 399 bytes --]


Blue are periods where the process is running, and grey where it’s
idle—e.g., waiting for data.  After each substitution completion,
guix-daemon becomes busy for a little while (computing the hash of the
store item, adding it to the database).  The startup activity of each
‘guix’ process is visible and in the second case it happens only once
for ‘guix substitute’.

Ludo’.