[Bug]: conky HTTP server hangs forever, cannot serve requests

[ctrlcctrlv]

What happened?

the built-in HTTP server is unreliable and hangs forever, deadlock inside liblua.so

Version

conky 1.19.7_pre compiled 2023-10-14 for Linux x86_64

Which OS/distro are you seeing the problem on?

Arch Linux

Conky config

conky.config = {
    alignment = 'top_right',
    background = true,
    border_width = 1,
    cpu_avg_samples = 2,
    default_color = 'white',
    default_outline_color = 'white',
    default_shade_color = 'white',
    double_buffer = true,
    draw_borders = false,
    draw_graph_borders = true,
    draw_outline = false,
    draw_shades = false,
    extra_newline = false,
    font = 'Unifont:size=12',
    gap_x = 60,
    gap_y = 60,
    minimum_height = 5,
    minimum_width = 8,
    net_avg_samples = 2,
    no_buffers = false,
    out_to_console = false,
    out_to_ncurses = false,
    out_to_stderr = false,
    out_to_x = true,
    out_to_http = true,
    http_port = 1234,
    http_refresh = true,
    if_up_strictness = 'address',
    own_window = true,
    own_window_class = 'conky',
    -- put conky above xfdesktop but below all other windows
    own_window_type = 'normal',
    own_window_transparent = false,
    own_window_argb_visual = true,
    own_window_argb_value = 128,
    own_window_hints = 'undecorated,below,sticky,skip_taskbar,skip_pager',
    show_graph_range = false,
    show_graph_scale = false,
    stippled_borders = 0,
    update_interval = 5.5,
    uppercase = false,
    use_spacer = 'none',
    use_xft = true,
}

function fs_hr(line, last_mount)
    if not last_mount then
        return
    end
    if not table then
        return
    end
    -- If the mount has a different prefix dir than the last mount, then
    -- print a horizontal rule.
    local last_prefix = last_mount:match('^(.+)/')
    local prefix = line:match('^(.+)/')
    return last_prefix ~= prefix
end

-- get zfs mounts
function get_zfs_mounts()
    local mounts = {}
    local last_mount = '/'
    local f = io.popen([[awk '$3=="zfs"{print $2}' /proc/mounts|sort]])
    table.insert(mounts, '${hr}')
    for line in f:lines() do
        if fs_hr(line, last_mount, mounts) then
            table.insert(mounts, "${hr}")
        end
        last_mount = line
        table.insert(mounts, line)
    end
    f:close()
    table.insert(mounts, '${hr}')
    return mounts
end

conky_info = [[
${color grey}Info:$color ${scroll 64 Conky $conky_version - $sysname $nodename $kernel $machine}
$hr
${color grey}Uptime:$color $uptime
${color grey}Frequency (in GHz):$color $freq_g
${color grey}RAM Usage:$color $mem/$memmax - $memperc% ${membar 4}
${color grey}Swap Usage:$color $swap/$swapmax - $swapperc% ${swapbar 4}
${color grey}CPU Usage:$color $cpu% ${cpubar 4}
${color grey}Processes:$color $processes  ${color grey}Running:$color $running_processes
$hr
]]

conky_fs = [[
${color grey}File systems:
 / $color${fs_used /}/${fs_size /} ${fs_bar 6 /}
]]

conky.net = 'eth1'
conky_net = [[
${goto 0}${color grey}Networking:
${goto 0}Up:$color ${upspeed "eth1"} ${color grey} - Down:$color ${downspeed "eth1"}
${goto 0}Total Up:$color ${totalup "eth1"} ${color grey} - Total Down:$color ${totaldown "eth1"}
]]

conky_ps = [[
${color grey}Name              PID     CPU%   MEM%
${color lightgrey} ${top name 1} ${top pid 1} ${top cpu 1} ${top mem 1}
${color lightgrey} ${top name 2} ${top pid 2} ${top cpu 2} ${top mem 2}
${color lightgrey} ${top name 3} ${top pid 3} ${top cpu 3} ${top mem 3}
${color lightgrey} ${top name 4} ${top pid 4} ${top cpu 4} ${top mem 4}
]]


for _, mount in ipairs(get_zfs_mounts()) do
    if mount:sub(1, 1) ~= '/' then
        conky_fs = conky_fs .. mount .. '\n'
    else
        conky_fs = conky_fs .. [[${color grey} ]] .. mount .. [[ $color${fs_used ]] .. mount .. [[}/${fs_size ]] .. mount .. [[} ${fs_bar 6 ]] .. mount .. [[}
]]
    end
end

conky.text = conky_info .. conky_fs .. conky_ps .. conky_net

Stack trace

++
#0  0x00007f7800616554 in ?? () from /usr/lib/liblua.so.5.4
#1  0x00007f7800617194 in ?? () from /usr/lib/liblua.so.5.4
#2  0x00007f7800611574 in ?? () from /usr/lib/liblua.so.5.4
#3  0x00007f7800630f34 in ?? () from /usr/lib/liblua.so.5.4
#4  0x00007f78006172ce in lua_pcallk () from /usr/lib/liblua.so.5.4
#5  0x000055c94e0c8688 in lua::state::call (this=0x55c94f99d040, nargs=nargs@entry=2, nresults=nresults@entry=1, errfunc=errfunc@entry=0)
    at /usr/include/c++/13.2.1/bits/shared_ptr_base.h:1665
#6  0x000055c94e0c88d2 in lua::state::gettable (this=<optimized out>, index=<optimized out>) at /home/fred/.cache/yay/conky-git/src/conky/src/luamm.cc:348
#7  0x000055c94e0c8914 in lua::state::getfield (this=<optimized out>, index=<optimized out>, k=<optimized out>) at /home/fred/.cache/yay/conky-git/src/conky/src/luamm.cc:327
#8  0x000055c94e0cce0d in conky::config_setting_template<double>::get (l=..., this=<optimized out>) at /home/fred/.cache/yay/conky-git/src/conky/src/setting.hh:219
#9  conky::display_output_http::begin_draw_text (this=<optimized out>) at /home/fred/.cache/yay/conky-git/src/conky/src/display-http.cc:176
#10 0x000055c94e08cbda in draw_text () at /home/fred/.cache/yay/conky-git/src/conky/src/conky.cc:1560
#11 0x000055c94e08d65f in draw_stuff () at /home/fred/.cache/yay/conky-git/src/conky/src/conky.cc:1638
#12 0x000055c94e0d1335 in conky::display_output_x11::main_loop_wait (this=<optimized out>, t=<optimized out>) at /home/fred/.cache/yay/conky-git/src/conky/src/display-x11.cc:575
#13 0x000055c94e08f172 in main_loop () at /home/fred/.cache/yay/conky-git/src/conky/src/conky.cc:1734
#14 0x000055c94e08069d in main (argc=1, argv=0x7ffc8c0c5068) at /home/fred/.cache/yay/conky-git/src/conky/src/main.cc:355

Relevant log output

No response

[ctrlcctrlv]

this also causes conky auto conf reload to fail because it gets stuck on trying to tear down the server, it hangs on MHD cleanup—

Using host libthread_db library "/usr/lib/libthread_db.so.1".
0x00007f77ffca74ae in ?? () from /usr/lib/libc.so.6
(gdb) bt
#0  0x00007f77ffca74ae in ?? () from /usr/lib/libc.so.6
#1  0x00007f77ffcac5f3 in ?? () from /usr/lib/libc.so.6
#2  0x00007f78008c012f in MHD_stop_daemon () from /usr/lib/libmicrohttpd.so.12
#3  0x000055c94e0ce09d in conky::out_to_http_setting::cleanup (this=<optimized out>, l=...)
    at /home/fred/.cache/yay/conky-git/src/conky/src/display-http.cc:108
#4  0x000055c94e0d4d25 in conky::cleanup_config_settings (l=...) at /home/fred/.cache/yay/conky-git/src/conky/src/setting.cc:312
#5  0x000055c94e08757e in clean_up () at /usr/include/c++/13.2.1/bits/unique_ptr.h:453
#6  0x000055c94e08a672 in reload_config () at /home/fred/.cache/yay/conky-git/src/conky/src/conky.cc:1853
#7  reload_config () at /home/fred/.cache/yay/conky-git/src/conky/src/conky.cc:1843
#8  0x000055c94e08f3f2 in main_loop () at /home/fred/.cache/yay/conky-git/src/conky/src/conky.cc:1808
#9  0x000055c94e08069d in main (argc=1, argv=0x7ffc8c0c5068) at /home/fred/.cache/yay/conky-git/src/conky/src/main.cc:355
#3  0x000055c94e0ce09d in conky::out_to_http_setting::cleanup (this=<optimized out>, l=...)
    at /home/fred/.cache/yay/conky-git/src/conky/src/display-http.cc:108
108	      MHD_stop_daemon(httpd);
(gdb) frame 4
#4  0x000055c94e0d4d25 in conky::cleanup_config_settings (l=...) at /home/fred/.cache/yay/conky-git/src/conky/src/setting.cc:312
312	    v[i - 1]->cleanup(l);

[ctrlcctrlv]

@brndnmtthws i don't quite understand why you chose to implement it how you did, why not do it all in lua?