[FFmpeg-trac] #6241(avformat:new): hls_flags delete_segments – file desctriptors not freeing, ffmpeg segfaults when system limit is reached

[FFmpeg]

#6241: hls_flags delete_segments – file desctriptors not freeing, ffmpeg segfaults
when system limit is reached
-------------------------------------+-------------------------------------
             Reporter:  rafamiga     |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:  avformat     |                  Version:  git-
             Keywords:  descriptors  |  master
  hls hls_flags delete_segments      |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 When delete_segments HLS flag is enabled, the FFmpeg binary segfaults when
 max open files limit is reached.

 How to reproduce:
 {{{
 /usr/local/bin/ffmpeg -loglevel info -thread_queue_size 1024 -f decklink
 -i DeckLink 4K Extreme at 2 -audio_input embedded -video_input sdi -threads 0
 -fflags +genpts -flags +global_header -c:a libfdk_aac
 -map 0:v -s:v 1280x720 -b:v 3600k -minrate:v 3000k -maxrate:v 3700k
 -bufsize:v 3600k -pix_fmt yuv420p -vf yadif
 -map 0:a -af aresample=48000 -b:a 128k
 -c:v libx264 -preset slow -profile:v main -x264opts keyint=100:min-
 keyint=100:scenecut=-1 -hls_time 4 -hls_list_size 5
 -hls_start_number_source epoch -hls_flags delete_segments
 /var/www/html/live/test1/live3600k.m3u8
 -map 0:v -s:v 1024x576 -b:v 2400k -minrate:v 2000k -maxrate:v 2500k
 -bufsize:v 2400k -pix_fmt yuv420p -vf yadif
 -map 0:a -af aresample=44100 -b:a 128k
 -c:v libx264 -preset slow -profile:v main -x264opts keyint=100:min-
 keyint=100:scenecut=-1 -hls_time 4 -hls_list_size 5
 -hls_start_number_source epoch -hls_flags delete_segments
 /var/www/html/live/test1/live2400k.m3u8
 -map 0:v -s:v 720x404 -b:v 1700k -minrate:v 1000k -maxrate:v 1800k
 -bufsize:v 1700k -pix_fmt yuv420p -vf yadif
 -map 0:a -af aresample=44100 -b:a 96k -c:v libx264 -preset slow -profile:v
 main -x264opts keyint=100:min-keyint=100:scenecut=-1 -hls_time 4
 -hls_list_size 5 -hls_start_number_source epoch -hls_flags delete_segments
 /var/www/html/live/test1/live1700k.m3u8
 -map 0:v -s:v 512x288 -b:v 900k -minrate:v 800k -maxrate:v 1000k
 -bufsize:v 900k -pix_fmt yuv420p -vf yadif
 -map 0:a -af aresample=44100 -b:a 64k
 -c:v libx264 -preset slow -profile:v main -x264opts keyint=100:min-
 keyint=100:scenecut=-1 -hls_time 4 -hls_list_size 5
 -hls_start_number_source epoch -hls_flags delete_segments
 /var/www/html/live/test1/live900k.m3u8
 -map 0:v -s:v 512x288 -b:v 450k -minrate:v 400k -maxrate:v 500k -bufsize:v
 450k -pix_fmt yuv420p -vf yadif
 -map 0:a -af aresample=44100 -b:a 64k
 -c:v libx264 -preset slow -profile:v main -x264opts keyint=100:min-
 keyint=100:scenecut=-1 -hls_time 4 -hls_list_size 5
 -hls_start_number_source epoch -hls_flags delete_segments
 /var/www/html/live/test1/live450k.m3u8
 -map 0:v -s:v 512x288 -b:v 120k -minrate:v 100k -maxrate:v 150k -bufsize:v
 120k -pix_fmt yuv420p -vf yadif
 -map 0:a -af aresample=32000 -b:a 32k
 -c:v libx264 -preset slow -profile:v main -x264opts keyint=100:min-
 keyint=100:scenecut=-1 -hls_time 4 -hls_list_size 5
 -hls_start_number_source epoch -hls_flags delete_segments
 /var/www/html/live/test1/live120k.m3u8

 Build:
 ffmpeg version N-83663-g7e9ba78 Copyright (c) 2000-2017 the FFmpeg
 developers
   built with gcc 4.9.2 (Debian 4.9.2-10)
   configuration: --prefix=/home/vagrant/ffmpeg-src/ffmpeg/
 --bindir=/usr/local --pkg-config-flags=--static --extra-
 cflags='-I/home/vagrant/decklink-include -static' --extra-
 ldflags=-L/home/vagrant/decklink-include --enable-gpl --disable-shared
 --disable-doc --enable-static --enable-libfdk-aac --enable-libfreetype
 --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis
 --enable-libvpx --enable-libx264 --enable-nonfree --enable-decklink
   libavutil      55. 47.100 / 55. 47.100
   libavcodec     57. 81.100 / 57. 81.100
   libavformat    57. 66.102 / 57. 66.102
   libavdevice    57.  2.100 / 57.  2.100
   libavfilter     6. 74.100 /  6. 74.100
   libswscale      4.  3.101 /  4.  3.101
   libswresample   2.  4.100 /  2.  4.100
   libpostproc    54.  2.100 / 54.  2.100
 Hyper fast Audio and Video encoder
 }}}

 How to check:
 {{{
 ... after a few minutes of encoding ...
 lsof -p `pidof ffmpeg`|grep '(deleted)'|wc -l
 1812
 }}}

 Temporary fix:
 {{{
 # grep NOFILE /etc/systemd/system/ffhls_decklink.service
 LimitNOFILE=65500
 }}}

 Comment:
 I've looked into the source and it seems that this is a problem in
 libavformat/hlsenc.c hls_delete_old_segments function:

 {{{
 proto = avio_find_protocol_name(s->filename);
         if (hls->method || (proto && !av_strcasecmp(proto, "http"))) {
             av_dict_set(&options, "method", "DELETE", 0);
             if ((ret = hls->avf->io_open(hls->avf, &out, path,
 AVIO_FLAG_WRITE, &options)) < 0)
                 goto fail;
             ff_format_io_close(hls->avf, &out);
         } else if (unlink(path) < 0) {
             av_log(hls, AV_LOG_ERROR, "failed to delete old segment %s:
 %s\n",
                                      path, strerror(errno));
         }
 }}}

 I'm no expert, in fact I'm a rookie when it comes to debuging ffmpeg
 source, but unlink() without some sort of close() [is it
 ff_format_io_close()?] may be the cause of this problem. [And the same
 applies to unlink(sub_path) found later in that function.]

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6241>
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