The following pipeline works well:

(/build/gstreamer-0.6/bin/gst-launch -v gnomevfssrc location=
/media/music/Evanescence/Fallen/Haunted.ogg ! spider ! osssink 2>&1)

But adding threads (like in the current netRhythmbox pipeline designed by
Company), I get:

(/build/gstreamer-0.6/bin/gst-launch -v \{ gnomevfssrc
location=/media/music/Evanescence/Fallen/Haunted.ogg ! queue \} ! \{ spider
! osssink \} 2>&1)
INFO (17360: 0) Initializing GStreamer Core Library version 0.6.1
INFO (17360: 0) CPU features: (00000000) MMX SSE
INFO (17360: 0) registry: loaded user_registry in 0.000073 seconds
          (/home/walters/.gstreamer/registry.xml)
INFO (17360: 0) registry: loaded global_registry in 0.151065 seconds
          (/build/gstreamer-0.6/var/cache/gstreamer-0.6/registry.xml)
GStreamer-INFO: 0 live buffer(s)
GStreamer-INFO: 0 live bufferpool(s)
GStreamer-INFO: 0 live event(s)
RUNNING pipeline
/pipeline0/thread0/gnomevfssrc0.src: active = TRUE
/pipeline0/thread0/queue0.sink: active = TRUE
/pipeline0/thread0/queue0.src: active = TRUE
/pipeline0/thread1/spider0/sink_ident.sink: active = TRUE
/pipeline0/thread1/spider0/sink_ident.src: active = TRUE
/pipeline0/thread1/spider0/src_0.sink: active = TRUE
/pipeline0/thread1/spider0/src_0.src: active = TRUE
/pipeline0/thread1/osssink0.sink: active = TRUE
/pipeline0/thread0/gnomevfssrc0.src: caps = (GstCaps *) { application/x-ogg;  }
/pipeline0/thread0/queue0.sink: caps = (GstCaps *) { application/x-ogg;  }
/pipeline0/thread0/queue0.src: caps = (GstCaps *) { application/x-ogg;  }
/pipeline0/thread1/spider0/sink_ident.sink: caps = (GstCaps *) {
application/x-ogg;  }
/pipeline0/thread1/spider0/sink_ident.sink: active = FALSE
/pipeline0/thread1/spider0/sink_ident.src: active = FALSE
/pipeline0/thread1/spider0/src_0.sink: active = FALSE
/pipeline0/thread1/spider0/src_0.src: active = FALSE
/pipeline0/thread1/spider0/sink_ident.sink: active = TRUE
/pipeline0/thread1/spider0/sink_ident.src: active = TRUE
/pipeline0/thread1/spider0/src_0.sink: active = TRUE
/pipeline0/thread1/spider0/src_0.src: active = TRUE
/pipeline0/thread0/gnomevfssrc0.src: caps = (GstCaps *) { application/x-ogg;  }
/pipeline0/thread0/queue0.sink: caps = (GstCaps *) { application/x-ogg;  }
/pipeline0/thread0/queue0.src: caps = (GstCaps *) { application/x-ogg;  }
/pipeline0/thread1/spider0/sink_ident.sink: caps = (GstCaps *) {
application/x-ogg;  }
/pipeline0/thread1/spider0/sink_ident.src: caps = (GstCaps *) {
application/x-ogg;  }
/pipeline0/thread1/spider0/vorbisfile0.sink: caps = (GstCaps *) {
application/x-ogg;  }
/pipeline0/thread1/spider0/vorbisfile0.sink: active = TRUE
/pipeline0/thread1/spider0/vorbisfile0.src: active = TRUE
 
(process:17363): GStreamer-WARNING **: FIXME: sending event in a running queue
 
(process:17362): GStreamer-WARNING **: internal error: push on pad
sink_ident:sink but it has no chainhandler
ERROR: /pipeline0/thread1/spider0/vorbisfile0: this is not a vorbis file
/pipeline0/thread1/spider0/vorbisfile0.sink: active = FALSE
/pipeline0/thread1/spider0/vorbisfile0.src: active = FALSE
/pipeline0/thread1/spider0/sink_ident.sink: active = FALSE
/pipeline0/thread1/spider0/sink_ident.src: active = FALSE
/pipeline0/thread1/spider0/src_0.sink: active = FALSE
/pipeline0/thread1/spider0/src_0.src: active = FALSE
/pipeline0/thread1/osssink0.sink: active = FALSE