Why does uploading files stop working when the thread pool is enabled in nginx-vod-module?

Question

Nginx

I made HLS the other day through nginx-vod-module, the problem appeared when I saw the growth of IOWAIT, noticed that I didn’t turn on the thread_pool thread pool, turned it on and immediately stopped giving the .ts file, I get m3u8, but the segments themselves didn’t send an error. I looked into the logs and there weren't any errors.

The config itself

server {

        listen 1024;
        root /var/www/html/files/;
        vod_mode local;

        # Performance
         location / {
                vod hls;
                vod_performance_counters perf_counters;
                vod_cache_buffer_size 512k;
                vod_output_buffer_pool 64k 32;
                vod_open_file_thread_pool pool_1;
                aio on;
        }

        location /vodstat {
                 vod_performance_counters perf_counters;
                vod_status;
                allow all;

        }


}

The pool itself was created before opening the http section {
added thread_pool pool_1 threads=16;

If you remove the line vod_open_file_thread_pool pool_1; then everything immediately works fine. What could be the problem?