LTTng » Babeltrace

While using babeltrace 2.0.3 with lttng-live (latest lttng version) we encountered the following assert:

(gdb) bt
#0  0x00007f9023fc3495 in raise () from /lib64/libc.so.6
#1  0x00007f9023fc4c75 in abort () from /lib64/libc.so.6
#2  0x00007f902391d8d3 in bt_common_abort () at common.c:2111
#3  0x00007f902391b9ff in bt_common_assert_failed (file=0x7f9023921495 "lttng-live.c", line=613, func=0x7f902393f500 <__func__.17246> "emit_inactivity_message", assertion=0x7f9023931c70 "stream_iter->trace->clock_class")
    at assert.c:40
#4  0x00007f902390be67 in emit_inactivity_message (stream_iter=0x472100, timestamp=<optimized out>, message=0x7ffe76aa8d98, lttng_live_msg_iter=0x471810) at lttng-live.c:613
#5  lttng_live_iterator_next_handle_one_quiescent_stream (message=0x7ffe76aa8d98, lttng_live_stream=0x472100, lttng_live_msg_iter=0x471810) at lttng-live.c:653
#6  lttng_live_iterator_next_msg_on_stream (curr_msg=0x7ffe76aa8d98, stream_iter=0x472100, lttng_live_msg_iter=0x471810) at lttng-live.c:961
#7  next_stream_iterator_for_trace (live_trace=0x4721a0, live_trace=0x4721a0, youngest_trace_stream_iter=<synthetic pointer>, lttng_live_msg_iter=0x471810) at lttng-live.c:1093
#8  next_stream_iterator_for_session (youngest_session_stream_iter=<synthetic pointer>, session=0x471d70, lttng_live_msg_iter=0x471810) at lttng-live.c:1325
#9  lttng_live_msg_iter_next (self_msg_it=<optimized out>, msgs=0x471780, capacity=15, count=0x7ffe76aa8ee8) at lttng-live.c:1518
#10 0x00007f90247031e2 in call_iterator_next_method (capacity=15, user_count=0x7ffe76aa8ee8, msgs=0x471780, iterator=0x4716a0) at iterator.c:803
#11 bt_message_iterator_next (iterator=0x4716a0, msgs=msgs@entry=0x7ffe76aa8ee0, user_count=user_count@entry=0x7ffe76aa8ee8) at iterator.c:859
#12 0x00007f90238841e9 in muxer_upstream_msg_iter_next (is_ended=<synthetic pointer>, muxer_upstream_msg_iter=0x471fc0) at muxer.c:399
#13 validate_muxer_upstream_msg_iter (is_ended=<synthetic pointer>, muxer_upstream_msg_iter=0x471fc0) at muxer.c:958
#14 validate_muxer_upstream_msg_iters (muxer_msg_iter=0x471650) at muxer.c:985
#15 muxer_msg_iter_do_next_one (msg=0x449850, muxer_msg_iter=0x471650, muxer_comp=0x4524f0) at muxer.c:1048
#16 muxer_msg_iter_do_next (count=0x7ffe76aa8f70, capacity=15, msgs=0x449850, muxer_msg_iter=0x471650, muxer_comp=0x4524f0) at muxer.c:1132
#17 muxer_msg_iter_next (self_msg_iter=0x471570, msgs=0x449850, capacity=15, count=0x7ffe76aa8f70) at muxer.c:1414
#18 0x00007f90247031e2 in call_iterator_next_method (capacity=15, user_count=0x7ffe76aa8f70, msgs=0x449850, iterator=0x471570) at iterator.c:803
#19 bt_message_iterator_next (iterator=0x471570, msgs=msgs@entry=0x7ffe76aa8f78, user_count=user_count@entry=0x7ffe76aa8f70) at iterator.c:859
#20 0x00007f9023821514 in bx_view_consume (comp=0x43a7d0) at traces//babeltrace-plugin/component.cc:272
#21 0x00007f90246ff3d8 in consume_graph_sink (comp=0x43a7d0) at graph.c:447
#22 consume_sink_node (graph=0x43b7d0, node=0x442e00) at graph.c:491
#23 consume_no_check (api_func=<synthetic pointer>, graph=0x43b7d0) at graph.c:566
#24 bt_graph_run (graph=0x43b7d0) at graph.c:710
#25 0x0000000000408a81 in cmd_run (cfg=0x451eb0) at babeltrace2.c:2485
#26 main (argc=<optimized out>, argv=<optimized out>) at babeltrace2.c:2673

I did initial prints in gdb to see that this is not some kind of obvious memory corruption:

(gdb) p stream_iter->trace
$1 = (struct lttng_live_trace *) 0x4721a0
(gdb) p stream_iter->trace->clock_class
$2 = (const bt_clock_class *) 0x0
(gdb) p stream_iter->trace[0]
$3 = {log_level = BT_LOGGING_LEVEL_WARNING, self_comp = 0x43c050, session = 0x471d70, id = 1, trace = 0x66fc30,
  trace_class = 0x66bef0, metadata = 0x66bb00, clock_class = 0x0, stream_iterators = 0x442d20,
  metadata_stream_state = LTTNG_LIVE_METADATA_STREAM_STATE_NOT_NEEDED}
(gdb) p stream_iter->trace->trace_class
$4 = (bt_trace_class *) 0x66bef0
(gdb) p stream_iter->trace->trace_class->stream_classes
$5 = (GPtrArray *) 0x43a4a0
(gdb) p stream_iter->trace->trace_class->stream_classes->len
$6 = 0

Unfortunately I can't attach the coredump here but I can provide any relevant information from it.