[RFE] reusable agent unix socket connections for charms: python bindings

[Dmitrii Shcherbakov]

Some charms can get quite heavy in terms of agent socket usage.

E.g. this https://paste.ubuntu.com/p/JFk7GzSjrh/ invocation of a single (!) keystone hook resulted in 202 connect(2) system calls to the same socket:

[pid 13985] connect(5, {sa_family=AF_LOCAL, sun_path=@"/var/lib/juju/agents/unit-keystone-6/agent.socket"}, 52) = 0

Since all of that communication happens via hook tool binaries we can easily add 202 fork(2)s and execve(2)s.

It seems that the ecosystem is at a stage where most of the charms are written in python 2 or 3 (or utilize https://pypi.org/project/six/) with new charms utilizing only python 3 (classic or reactive).

It would be good to avoid all of that overhead and have a python library that could be used in charm-helpers that would provide an API that would only utilize a single unix socket connection to the juju agent during the runtime of a given charm hook execution.

[John A Meinel (jameinel)]

I don't think it would be particularly hard. The existing API on the socket
is essentially just passing the []string of CLI args. It should mostly be
just a change to charmhelpers to maintain a socket connection and send the
requests.
That said, it may not be possible to pipeline the requests today. It might
require reconnecting to issue a new request. But it would avoid to fork
overhead

John
=:->

On Mon, May 14, 2018, 01:35 Tim Penhey <email address hidden> wrote:

> ** Changed in: juju
> Status: New => Triaged
>
> ** Changed in: juju
> Importance: Undecided => Wishlist
>
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> Title:
> [RFE] reusable agent unix socket connections for charms: python
> bindings
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[Canonical Juju QA Bot (juju-qa-bot)]

This bug has not been updated in 2 years, so we're marking it Low importance. If you believe this is incorrect, please update the importance.