I've been able to reproduce this in my recent kdenlive build using the same MLT/ffmpeg libraries.
I'll be building the latest ffmpeg and MLT from HEAD later. If they appear to be stable and usable I'll re-test against the new MLT with openshot and kdenlive.
Lightweight thread (LWP) 20452 is running, and pushing the CPU core to 61%. LWP 20450 is sleeping on a futex.
(gdb) ^C
Program received signal SIGINT, Interrupt.
[Switching to Thread 0x7f6001f7f750 (LWP 20387)]
0x00007f5ffdc41496 in *__GI___poll (fds=0x3bb60a0, nfds=5, timeout=299) at ../sysdeps/unix/sysv/linux/poll.c:87
87 ../sysdeps/unix/sysv/linux/poll.c: No such file or directory.
in ../sysdeps/unix/sysv/linux/poll.c
(gdb) info threads
64 Thread 0x7f5fd180a950 (LWP 20453) pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
63 Thread 0x7f5fd700e950 (LWP 20452) 0x00007f5ff101e390 in ?? () from /usr/lib/libpulse.so.0
62 Thread 0x7f5fd200b950 (LWP 20451) 0x00007f5ffdc41496 in *__GI___poll (fds=0x621fbd0, nfds=2, timeout=332)
at ../sysdeps/unix/sysv/linux/poll.c:87
61 Thread 0x7f5fe03d3950 (LWP 20450) pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
60 Thread 0x7f5fe0bd4950 (LWP 20449) pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
23 Thread 0x7f5fd680d950 (LWP 20412) pthread_cond_timedwait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:217
19 Thread 0x7f5fdebd0950 (LWP 20408) pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
18 Thread 0x7f5fde3cf950 (LWP 20407) pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
17 Thread 0x7f5fdfbd2950 (LWP 20406) pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
16 Thread 0x7f5fdf3d1950 (LWP 20405) pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
* 1 Thread 0x7f6001f7f750 (LWP 20387) 0x00007f5ffdc41496 in *__GI___poll (fds=0x3bb60a0, nfds=5, timeout=299)
at ../sysdeps/unix/sysv/linux/poll.c:87
(gdb) thread 63
[Switching to thread 63 (Thread 0x7f5fd700e950 (LWP 20452))]#0 0x00007f5ff101e390 in ?? ()
from /usr/lib/libpulse.so.0
(gdb) bt
#0 0x00007f5ff101e390 in ?? () from /usr/lib/libpulse.so.0
#1 0x00007f5fe18edb48 in ?? () from /usr/lib/alsa-lib/libasound_module_pcm_pulse.so
#2 0x00007f5ff190bdf2 in snd_pcm_ioplug_hw_ptr_update (pcm=0x6224630) at pcm_ioplug.c:56
#3 0x00007f5ff190c685 in snd_pcm_ioplug_avail_update (pcm=0x7c75a60) at pcm_ioplug.c:627
#4 0x00007f5ff18cd8e2 in snd1_pcm_write_areas (pcm=0x6224630, areas=0x7f5fd700dfa0, offset=0, size=512,
func=0x7f5ff190c7b0 <ioplug_priv_transfer_areas>) at pcm.c:6627
#5 0x00007f5ff190cb4a in snd_pcm_ioplug_writei (pcm=0x6224630, buffer=<value optimized out>, size=512)
at pcm_ioplug.c:561
#6 0x00007f5ff1b9454c in ALSA_PlayAudio (this=0x7f5fcc0447e0) at ../../src/audio/alsa/SDL_alsa_audio.c:325
#7 0x00007f5ff1b6708e in SDL_RunAudio (audiop=<value optimized out>) at ../../src/audio/SDL_audio.c:215
#8 0x00007f5ff1b6eb77 in SDL_RunThread (data=0x8282e10) at ../../src/thread/SDL_thread.c:202
#9 0x00007f5ff1bb7e59 in RunThread (data=0x7c75a60) at ../../src/thread/pthread/SDL_systhread.c:47
#10 0x00007f5ffd74c3ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#11 0x00007f5ffdc4afcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#12 0x0000000000000000 in ?? ()
(gdb) bt full
#0 0x00007f5ff101e390 in ?? () from /usr/lib/libpulse.so.0
No symbol table info available.
#1 0x00007f5fe18edb48 in ?? () from /usr/lib/alsa-lib/libasound_module_pcm_pulse.so
No symbol table info available.
#2 0x00007f5ff190bdf2 in snd_pcm_ioplug_hw_ptr_update (pcm=0x6224630) at pcm_ioplug.c:56
io = (ioplug_priv_t *) 0x76d7aa0
hw = <value optimized out>
#3 0x00007f5ff190c685 in snd_pcm_ioplug_avail_update (pcm=0x7c75a60) at pcm_ioplug.c:627
io = (ioplug_priv_t *) 0x76d7aa0
avail = <value optimized out>
#4 0x00007f5ff18cd8e2 in snd1_pcm_write_areas (pcm=0x6224630, areas=0x7f5fd700dfa0, offset=0, size=512,
func=0x7f5ff190c7b0 <ioplug_priv_transfer_areas>) at pcm.c:6627
frames = 512
avail = 473
xfer = 0
err = 0
state = SND_PCM_STATE_RUNNING
#5 0x00007f5ff190cb4a in snd_pcm_ioplug_writei (pcm=0x6224630, buffer=<value optimized out>, size=512)
at pcm_ioplug.c:561
No locals.
#6 0x00007f5ff1b9454c in ALSA_PlayAudio (this=0x7f5fcc0447e0) at ../../src/audio/alsa/SDL_alsa_audio.c:325
status = <value optimized out>
sample_len = -40516992
sample_buf = (short int *) 0x76d57b0
#7 0x00007f5ff1b6708e in SDL_RunAudio (audiop=<value optimized out>) at ../../src/audio/SDL_audio.c:215
audio = (SDL_AudioDevice *) 0x7f5fcc0447e0
stream = (
Uint8 *) 0x76d57b0 "\a\nv��\f\210\002P\016�\005\210\016�\a�\r�\a\003\v�\005r\006�\001�\001��\212�����+���R�\006�&�0�M�6�?���F�{�\231�\214���?�\222�G�\230�g���Y���\220��ߴ���w�\177��ܨ���\a�Kܪ�/�\031���"
stream_len = 2048
udata = (void *) 0x3a5bb70
---Type <return> to continue, or q <return> to quit---
fill = (void (*)(void *, Uint8 *, int)) 0x7f5ff1e01eb0 <sdl_fill_audio>
silence = 0
#8 0x00007f5ff1b6eb77 in SDL_RunThread (data=0x8282e10) at ../../src/thread/SDL_thread.c:202
userfunc = (int (*)(void *)) 0x7f5ff1b66fd0 <SDL_RunAudio>
userdata = (void *) 0x7f5fcc0447e0
#9 0x00007f5ff1bb7e59 in RunThread (data=0x7c75a60) at ../../src/thread/pthread/SDL_systhread.c:47
No locals.
#10 0x00007f5ffd74c3ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
__res = <value optimized out>
pd = (struct pthread *) 0x7f5fd700e950
unwind_buf = {cancel_jmp_buf = {{jmp_buf = {0, 7241345342359839719, 8392704, 0, 140050326876224, 140049769119440, -7295335270796647449, -7295382995374201881}, mask_was_saved = 0}}, priv = {pad = {
0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}} not_first_call = <value optimized out>
robust = <value optimized out>
#11 0x00007f5ffdc4afcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
No locals.
#12 0x0000000000000000 in ?? ()
No symbol table info available.
(gdb) thread 61
[Switching to thread 61 (Thread 0x7f5fe03d3950 (LWP 20450))]#0 pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
261 ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: No such file or directory.
in ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S
Current language: auto; currently asm
(gdb) bt
#0 pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:261
#1 0x00007f6001b92efd in consumer_read_ahead_thread (arg=<value optimized out>) at mlt_consumer.c:656
#2 0x00007f5ffd74c3ba in start_thread (arg=<value optimized out>) at pthread_create.c:297
#3 0x00007f5ffdc4afcd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#4 0x0000000000000000 in ?? ()
I've been able to reproduce this in my recent kdenlive build using the same MLT/ffmpeg libraries.
I'll be building the latest ffmpeg and MLT from HEAD later. If they appear to be stable and usable I'll re-test against the new MLT with openshot and kdenlive.
ps -em -o pcpu,lwp, stat,pid, tid,class, psr,wchan, args
103 - - 20387 - - - - /usr/bin/kdenlive
6.7 20387 Sl+ - 20387 TS 0 poll -
0.0 20405 Sl+ - 20405 TS 1 futex_ -
0.0 20406 Sl+ - 20406 TS 1 futex_ -
0.0 20407 Sl+ - 20407 TS 0 futex_ -
0.0 20408 Sl+ - 20408 TS 0 futex_ -
1.2 20412 Sl+ - 20412 TS 0 futex_ -
0.0 20449 Sl+ - 20449 TS 0 futex_ -
48.8 20450 Sl+ - 20450 TS 0 futex_ -
0.5 20451 Sl+ - 20451 TS 0 poll -
61.0 20452 Rl+ - 20452 TS 1 - -
1.1 20453 Sl+ - 20453 TS 1 futex_ -
Lightweight thread (LWP) 20452 is running, and pushing the CPU core to 61%. LWP 20450 is sleeping on a futex.
(gdb) ^C unix/sysv/ linux/poll. c:87 unix/sysv/ linux/poll. c: No such file or directory. unix/sysv/ linux/poll. c
Program received signal SIGINT, Interrupt.
[Switching to Thread 0x7f6001f7f750 (LWP 20387)]
0x00007f5ffdc41496 in *__GI___poll (fds=0x3bb60a0, nfds=5, timeout=299) at ../sysdeps/
87 ../sysdeps/
in ../sysdeps/
(gdb) info threads cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 libpulse. so.0 unix/sysv/ linux/poll. c:87 cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 cond_timedwait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_timedwait. S:217 cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 unix/sysv/ linux/poll. c:87
64 Thread 0x7f5fd180a950 (LWP 20453) pthread_
at ../nptl/
63 Thread 0x7f5fd700e950 (LWP 20452) 0x00007f5ff101e390 in ?? () from /usr/lib/
62 Thread 0x7f5fd200b950 (LWP 20451) 0x00007f5ffdc41496 in *__GI___poll (fds=0x621fbd0, nfds=2, timeout=332)
at ../sysdeps/
61 Thread 0x7f5fe03d3950 (LWP 20450) pthread_
at ../nptl/
60 Thread 0x7f5fe0bd4950 (LWP 20449) pthread_
at ../nptl/
23 Thread 0x7f5fd680d950 (LWP 20412) pthread_
at ../nptl/
19 Thread 0x7f5fdebd0950 (LWP 20408) pthread_
at ../nptl/
18 Thread 0x7f5fde3cf950 (LWP 20407) pthread_
at ../nptl/
17 Thread 0x7f5fdfbd2950 (LWP 20406) pthread_
at ../nptl/
16 Thread 0x7f5fdf3d1950 (LWP 20405) pthread_
at ../nptl/
* 1 Thread 0x7f6001f7f750 (LWP 20387) 0x00007f5ffdc41496 in *__GI___poll (fds=0x3bb60a0, nfds=5, timeout=299)
at ../sysdeps/
(gdb) thread 63 libpulse. so.0 libpulse. so.0 alsa-lib/ libasound_ module_ pcm_pulse. so ioplug_ hw_ptr_ update (pcm=0x6224630) at pcm_ioplug.c:56 ioplug_ avail_update (pcm=0x7c75a60) at pcm_ioplug.c:627 write_areas (pcm=0x6224630, areas=0x7f5fd70 0dfa0, offset=0, size=512, 0x7f5ff190c7b0 <ioplug_ priv_transfer_ areas>) at pcm.c:6627 ioplug_ writei (pcm=0x6224630, buffer=<value optimized out>, size=512) 447e0) at ../../src/ audio/alsa/ SDL_alsa_ audio.c: 325 audio/SDL_ audio.c: 215 thread/ SDL_thread. c:202 thread/ pthread/ SDL_systhread. c:47 create. c:297 unix/sysv/ linux/x86_ 64/clone. S:112
[Switching to thread 63 (Thread 0x7f5fd700e950 (LWP 20452))]#0 0x00007f5ff101e390 in ?? ()
from /usr/lib/
(gdb) bt
#0 0x00007f5ff101e390 in ?? () from /usr/lib/
#1 0x00007f5fe18edb48 in ?? () from /usr/lib/
#2 0x00007f5ff190bdf2 in snd_pcm_
#3 0x00007f5ff190c685 in snd_pcm_
#4 0x00007f5ff18cd8e2 in snd1_pcm_
func=
#5 0x00007f5ff190cb4a in snd_pcm_
at pcm_ioplug.c:561
#6 0x00007f5ff1b9454c in ALSA_PlayAudio (this=0x7f5fcc0
#7 0x00007f5ff1b6708e in SDL_RunAudio (audiop=<value optimized out>) at ../../src/
#8 0x00007f5ff1b6eb77 in SDL_RunThread (data=0x8282e10) at ../../src/
#9 0x00007f5ff1bb7e59 in RunThread (data=0x7c75a60) at ../../src/
#10 0x00007f5ffd74c3ba in start_thread (arg=<value optimized out>) at pthread_
#11 0x00007f5ffdc4afcd in clone () at ../sysdeps/
#12 0x0000000000000000 in ?? ()
(gdb) bt full libpulse. so.0 alsa-lib/ libasound_ module_ pcm_pulse. so ioplug_ hw_ptr_ update (pcm=0x6224630) at pcm_ioplug.c:56 ioplug_ avail_update (pcm=0x7c75a60) at pcm_ioplug.c:627 write_areas (pcm=0x6224630, areas=0x7f5fd70 0dfa0, offset=0, size=512, 0x7f5ff190c7b0 <ioplug_ priv_transfer_ areas>) at pcm.c:6627 STATE_RUNNING ioplug_ writei (pcm=0x6224630, buffer=<value optimized out>, size=512) 447e0) at ../../src/ audio/alsa/ SDL_alsa_ audio.c: 325 audio/SDL_ audio.c: 215 �\f\210\ 002P\016� \005\210\ 016�\a� \r�\a\003\ v�\005r\ 006�\001� \001��\ 212���� �+���R� \006�&� 0�M�6�? ���F�{� \231�\214� ��?�\222� G�\230� g���Y�� �\220�� ߴ���w�\ 177��ܨ� ��\a�Kܪ� /�\031� ��" thread/ SDL_thread. c:202 thread/ pthread/ SDL_systhread. c:47 create. c:297 9719, 8392704, 0, 140050326876224,
14004976911944 0, -72953352707966 47449, -72953829953742 01881}, mask_was_saved = 0}}, priv = {pad = {
not_first_ call = <value optimized out> unix/sysv/ linux/x86_ 64/clone. S:112
#0 0x00007f5ff101e390 in ?? () from /usr/lib/
No symbol table info available.
#1 0x00007f5fe18edb48 in ?? () from /usr/lib/
No symbol table info available.
#2 0x00007f5ff190bdf2 in snd_pcm_
io = (ioplug_priv_t *) 0x76d7aa0
hw = <value optimized out>
#3 0x00007f5ff190c685 in snd_pcm_
io = (ioplug_priv_t *) 0x76d7aa0
avail = <value optimized out>
#4 0x00007f5ff18cd8e2 in snd1_pcm_
func=
frames = 512
avail = 473
xfer = 0
err = 0
state = SND_PCM_
#5 0x00007f5ff190cb4a in snd_pcm_
at pcm_ioplug.c:561
No locals.
#6 0x00007f5ff1b9454c in ALSA_PlayAudio (this=0x7f5fcc0
status = <value optimized out>
sample_len = -40516992
sample_buf = (short int *) 0x76d57b0
#7 0x00007f5ff1b6708e in SDL_RunAudio (audiop=<value optimized out>) at ../../src/
audio = (SDL_AudioDevice *) 0x7f5fcc0447e0
stream = (
Uint8 *) 0x76d57b0 "\a\nv�
stream_len = 2048
udata = (void *) 0x3a5bb70
---Type <return> to continue, or q <return> to quit---
fill = (void (*)(void *, Uint8 *, int)) 0x7f5ff1e01eb0 <sdl_fill_audio>
silence = 0
#8 0x00007f5ff1b6eb77 in SDL_RunThread (data=0x8282e10) at ../../src/
userfunc = (int (*)(void *)) 0x7f5ff1b66fd0 <SDL_RunAudio>
userdata = (void *) 0x7f5fcc0447e0
#9 0x00007f5ff1bb7e59 in RunThread (data=0x7c75a60) at ../../src/
No locals.
#10 0x00007f5ffd74c3ba in start_thread (arg=<value optimized out>) at pthread_
__res = <value optimized out>
pd = (struct pthread *) 0x7f5fd700e950
unwind_buf = {cancel_jmp_buf = {{jmp_buf = {0, 724134534235983
0x0, 0x0, 0x0, 0x0}, data = {prev = 0x0, cleanup = 0x0, canceltype = 0}}}
robust = <value optimized out>
#11 0x00007f5ffdc4afcd in clone () at ../sysdeps/
No locals.
#12 0x0000000000000000 in ?? ()
No symbol table info available.
(gdb) thread 61 cond_wait@ @GLIBC_ 2.3.2 () sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S: No such file or directory. sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S cond_wait@ @GLIBC_ 2.3.2 () at ../nptl/ sysdeps/ unix/sysv/ linux/x86_ 64/pthread_ cond_wait. S:261 read_ahead_ thread (arg=<value optimized out>) at mlt_consumer.c:656 create. c:297 unix/sysv/ linux/x86_ 64/clone. S:112
[Switching to thread 61 (Thread 0x7f5fe03d3950 (LWP 20450))]#0 pthread_
at ../nptl/
261 ../nptl/
in ../nptl/
Current language: auto; currently asm
(gdb) bt
#0 pthread_
#1 0x00007f6001b92efd in consumer_
#2 0x00007f5ffd74c3ba in start_thread (arg=<value optimized out>) at pthread_
#3 0x00007f5ffdc4afcd in clone () at ../sysdeps/
#4 0x0000000000000000 in ?? ()