Ubuntu 16.04下Nginx截断php-fpm响应的问题排查求助

我们环境为Ubuntu 16.04，安装Yandex Odyssey 1.0rc1后，发现Nginx会截断php-fpm返回的响应内容，截断长度约2-3字节。切换为pgbouncer后问题依然存在。

已完成以下排查：

• PHP端确认完整发送所有响应数据；
• 业务需保留自行计算并设置的Content-Length字段，移除该字段则响应正常，但此设置为业务必需，无法更改；
• 已检查Nginx与PHP的目录权限，重装Nginx和php-fpm后问题仍未解决。

特求助排查原因，附当前Nginx配置：

#user  nobody;
worker_processes  1;

#thread_pool first threads=128 max_queue=0;
#thread_pool second threads=64;


#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    server_names_hash_bucket_size  64;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    gzip  on;
    
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; 
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_prefer_server_ciphers on;
#    server {
#        listen       80;
#        server_name  localhost;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

#        location / {
#            root   html;
#            index  index.html index.htm;
#        }

        #error_page  404              /404.html;

        # redirect server error pages to the static page /50x.html
        #
        error_page   500 502 503 504  /50x.html;
#        location = /50x.html {
#            root   html;
#        }

        # proxy the PHP scripts to Apache listening on 127.0.0.1:80
        #
        #location ~ \.php$ {
        #    proxy_pass   http://127.0.0.1;
        #}

        # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
        #
        #location ~ \.php$ {
        #    root           html;
        #    fastcgi_pass   127.0.0.1:9000;
        #    fastcgi_index  index.php;
        #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
        #    include        fastcgi_params;
        #}

        # deny access to .htaccess files, if Apache's document root
        # concurs with nginx's one
        #
        #location ~ /\.ht {
        #    deny  all;
        #}
        include conf.d/*.conf;
#    }


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    #server {
    #    listen       8000;
    #    listen       somename:8080;
    #    server_name  somename  alias  another.alias;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}

    include sites-enabled/*.conf;
    # HTTPS server
    #
    #server {
    #    listen       443 ssl;
    #    server_name  localhost;

    #    ssl_certificate      cert.pem;
    #    ssl_certificate_key  cert.key;

    #    ssl_session_cache    shared:SSL:1m;
    #    ssl_session_timeout  5m;

    #    ssl_ciphers  HIGH:!aNULL:!MD5;
    #    ssl_prefer_server_ciphers  on;

    #    location / {
    #        root   html;
    #        index  index.html index.htm;
    #    }
    #}

}

内容的提问来源于stack exchange，提问作者Владимир Мартемьянов