If you leave spotify open all the time without closing, you ends up that pulse audio can not accept more connections anymore as all of the available slots are used by spotify.
Even if I did some lazy testing (just use it normally and randomly check the connections in use), I could see up to about 10 new connections a day. Currently, spotify use 'only' 29 connections!
$ pactl list clients | grep Spotify | wc -l
$ pactl list clients
Owner Module: 12
application.name = "Spotify"
native-protocol.peer = "UNIX socket client"
native-protocol.version = "32"
application.process.id = "8216"
application.process.user = "phantom"
application.process.host = "casper"
application.process.binary = "spotify"
window.x11.display = ":0"
application.language = "en_US.UTF-8"
application.process.machine_id = "8a2f57b657b34cdb6bbefb72567ddd05"
application.icon_name = "spotify-client"
It shouln't grow.
I theorise that the bug is caused by spotify that do not release the audio when it is paused/stopped, and start a new one when you play it back.
The symptoms is: everything work fine for a few days until one application that use PA can't play back. It can be some games, apps, or spotify itself. From that point on, there will be no more sound globally for all apps that try to open a new PA connection. Spotify will say that the song is unavailable and you may import it.
The work around: restart spotify to free up all the connections.
Current OS: Gentoo