Всем привет и с Наступающим!

Наблюдаем тут очень странную проблему.
Иногда (далеко не всегда, но проблемных запросов не так мало) $request_time запросов к статическим файликам (.png) занимает странно долгое время:

($request_time запросов из лога ниже)
159.571 cекунд
57.523 cекунд
45.826 cекунд
41.506 cекунд
31.942 cекунд
33.334 cекунд



> 29 Dec 2015 15:28:28.666 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:28:28 +0300] "GET /path1/img/screenshots/simpleLook@2x.jpg HTTP/1.1" 200 327397 "https://www.domain.com/path1/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.135 Safari/537.36 Edge/12.10240" 159.571 us-west-2 TLSv1.2/ECDHE-RSA-AES128-SHA
> 29 Dec 2015 15:29:23.271 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:29:22 +0300] "GET /path1/img/screenshots/complexLook@2x.jpg HTTP/1.1" 200 163557 "https://www.domain.com/path1/" "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.101 Safari/537.36" 57.523 us-west-2 TLSv1.2/ECDHE-RSA-AES128-SHA
> 29 Dec 2015 15:29:28.989 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:29:28 +0300] "GET /path1/img/screenshots/complexLook@2x.jpg HTTP/1.1" 200 531273 "http://www.domain.com/path1/" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36" 45.826 eu-west-1 -/-
> 29 Dec 2015 15:29:45.595 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:29:45 +0300] "GET /path2/img/screenshots/path2_editor@2x.png HTTP/1.1" 200 425702 "https://www.domain.com/path2/" "Mozilla/5.0 (Linux; Android 4.2.2; GT-S7582 Build/JDQ39) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.133 Mobile Safari/537.36" 41.506 eu-west-1 TLSv1.2/ECDHE-RSA-AES128-SHA
> 29 Dec 2015 15:29:47.426 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:29:47 +0300] "GET /path3/features/img/path3_database@2.png HTTP/1.1" 200 250227 "https://www.domain.com/path3/features/" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.86 Safari/537.36" 31.942 eu-west-1 TLSv1.2/ECDHE-RSA-AES128-SHA
> 29 Dec 2015 15:29:58.045 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:29:57 +0300] "GET /path2/img/screenshots/path2_codeAnalysis@2x.png HTTP/1.1" 200 320568 "http://www.domain.com/path2/" "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 10.0; WOW64; Trident/7.0)" 33.334 eu-west-1 -/-
> 29 Dec 2015 15:30:02.628 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:30:02 +0300] "GET /path2/img/screenshots/path2_refactoring@2x.png HTTP/1.1" 200 385996 "http://www.domain.com/path2/" "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 10.0; WOW64; Trident/7.0)" 37.977 eu-west-1 -/-
> 29 Dec 2015 15:30:04.674 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:30:04 +0300] "GET /path2/img/screenshots/path2_editor@2x.png HTTP/1.1" 200 271924 "http://www.domain.com/path2/" "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 10.0; WOW64; Trident/7.0)" 38.863 eu-west-1 -/-
> 29 Dec 2015 15:30:04.674 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:30:04 +0300] "GET /path2/img/screenshots/path2_navigation@2x.png HTTP/1.1" 200 541204 "http://www.domain.com/path2/" "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 10.0; WOW64; Trident/7.0)" 39.843 eu-west-1 -/-
> 29 Dec 2015 15:30:04.674 XXX.XXX.XXX.XXX - - [29/Dec/2015:15:30:04 +0300] "GET /path2/img/screenshots/path2_debugging@2x.png HTTP/1.1" 200 358324 "http://www.domain.com/path2/" "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 10.0; WOW64; Trident/7.0)" 39.685 eu-west-1 -/-


Сам nginx вот такой вот версии:

# nginx -V
nginx version: nginx/1.6.2
built by gcc 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC)
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-http_ssl_module --with-http_realip_module --with-http_addition_module --with-http_sub_module --with-http_dav_module --with-http_flv_module --with-http_mp4_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_random_index_module --with-http_secure_link_module --with-http_stub_status_module --with-http_auth_request_module --with-mail --with-mail_ssl_module --with-file-aio --with-ipv6 --with-http_spdy_module --with-cc-opt='-O2 -g -pipe -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic'



nginx запущен в docker(е), png-файлики лежат на локальной файловой системе и используется вот такой вот конфиг:


location / {
try_files $uri @com_app_server_$scheme;
index index.jsp index.html index.htm;
}
#


location @com_app_server_http {

proxy_pass http://com_loadbalancer;
proxy_buffering on;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;

}


location @com_app_server_https {

proxy_pass http://com_loadbalancer_secure;
proxy_buffering on;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;


}
#


iostat не показывает никаких проблем при обращении к диску.

Как можно понять причину такой долгой отдачи статики (файликов с диска)?

--
s.