block when using multiple appsink

[Dušan Poizl]

I am using this pipeline filesrc ! decodebin name=dec ! appsink
name=videosink sync=false max-buffer=8 dec. ! appsink name=audiosink
max-buffers=64 sync=false

Problem is that sometimes I got blocked at gst_app_sink_pull_sample().
It appears that if I pull too much data from one appsink it locks even
if there should be some samples. I am pulling samples from single thread
so if gst_app_sink_pull_sample() block it result in deadlock. What
strategy should I apply so I don't block whole pipeline?