Comment 10 for bug 403154

After installing the libasound2 and SDL-1.2 dbgsym (debug symbol) packages

sudo apt-get install libasound2-dbgsym libsdl1.2debian-all-dbgsym

I've gathered more information on what the spinning thread is doing:

(gdb) bt
#0 0x00007f62548bf496 in *__GI___poll (fds=0x7f6238e0af20, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:87
#1 0x00007f624470d64c in snd1_pcm_wait_nocheck (pcm=0x3ad4900, timeout=-1) at pcm.c:2361
#2 0x00007f624470d9b7 in snd1_pcm_write_areas (pcm=0x3ad4900, areas=0x7f6238e0b000, offset=0, size=512,
    func=0x7f624474c7b0 <ioplug_priv_transfer_areas>) at pcm.c:6640
#3 0x00007f624474cb4a in snd_pcm_ioplug_writei (pcm=0x3ad4900, buffer=<value optimized out>, size=512)
    at pcm_ioplug.c:561
#4 0x00007f62449d454c in ALSA_PlayAudio (this=0x7f62361b8790) at ../../src/audio/alsa/SDL_alsa_audio.c:325
#5 0x00007f62449a708e in SDL_RunAudio (audiop=<value optimized out>) at ../../src/audio/SDL_audio.c:215
#6 0x00007f62449aeb77 in SDL_RunThread (data=0x3b46800) at ../../src/thread/SDL_thread.c:202
#7 0x00007f62449f7e59 in RunThread (data=0x7f6238e0af20) at ../../src/thread/pthread/SDL_systhread.c:47
#8 0x00007f62554003ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#9 0x00007f62548c8fcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#10 0x0000000000000000 in ?? ()