Can't aplay/arecord simultaneously inside and outside of linux container

[GitHub issues - opened <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-utils issue #62 was opened from fearless-fan:

Hi,
I run into a problem that can't aplay/arecord simultaneously inside and outside of linux container. 

Steps to reproduce:
1. go into container's shell and exec a record command. 

~ # lxc-attach -n Default -P /tmp/run/lxc
/ # arecord -d 60 /tmp/test.wav &
/ # Recording WAVE '/tmp/test.wav' : Unsigned 8 bit, Rate 8000 Hz, Mono
/ # ps
PID   USER     TIME   COMMAND
      1 root       0:00 /sbin/init
      3 root       0:00 /bin/sh
1519 root       0:00 arecord -d 60 /tmp/test.wav
1520 root       0:00 /bin/ash
1521 root       0:00 ps

2. exit and exec another record command outside of container

/ # exit
~ # arecord -d 60 /tmp/test.wav &
~ # ALSA lib pcm_dsnoop.c:641:(snd_pcm_dsnoop_open) unable to open slave
arecord: main:830: audio open error: Device or resource busy

[1]+  Done(1)                    arecord -d 60 /tmp/test.wav

3. playback has same problem as below

ALSA lib pcm_dmix.c:1089:(snd_pcm_dmix_open) unable to open slave
aplay: main:830: audio open error: Device or resource busy

Expect:
It should be allowed to play/record simultaneously inside and outside of linux container.

Here's my asound.conf:

~ # cat etc/asound.conf
pcm.asymed {
    type asym
    playback.pcm "dmix:0,0"
    capture.pcm "dsnoop:0,0"
}

pcm.!default {
    type plug
    slave.pcm "asymed"
}

ctl.!default {
        type hw
        card 0
}

Is there anyone has experience of how to address it? Thank you.

Issue URL     : https://github.com/alsa-project/alsa-utils/issues/62
Repository URL: https://github.com/alsa-project/alsa-utils