strange 499 response code ??

[jonefee]

my server use  nginx+php-fpm ,nginx as reverse proxy server,, but  our nginx
access log  got a lot of 499 response code,,,,the document say that 499
means "client abort the connection ",,,,,i think the the reason cause "
client abort connection" comes from two: the first is client is in weak
network environment, client request can't be delivered successfully, and
client has canceled the request. the second is php-fpm is too busy,,,such as
for a long time   nginx can't get the response from upstream server(php-fpm)
,,,and the client canceled the request.


    my question is  the first reason can be accepted . but the second can't.
  since i checked the nginx access log,, when there is 499 response code in
nginx access log file ,,,there  is always no "upstream_response_time" field 
value in it,   seems the php-fpm is not busy and can server it successfully
. here is some sample 499 nginx access log and some explanation:



171.213.141.240 -       31/Oct/2012:13:09:34 +0800      POST
/php/xyz/iface/?key=be7fc0cdf0afbfedff1e09ec6443823a&device_id=351870052329449&network=1&ua=LT18i&os=2.3.4&version=3.7&category_id=2&f_ps=10&s=5&ps=30&pn=1&pcat=2&up_tm=1351655451272
HTTP/1.1    499     0($body_bytes_sent)       -       Dalvik/1.4.0 (Linux;
U; Android 2.3.4; LT18i Build/4.0.2.A.0.62)      21($content_length)     
2.448($request_time)   -($upstream_response_time)       -       -       -
124.236.132.41  -       31/Oct/2012:13:09:34 +0800      POST
/php/xyz/iface/?key=3179f25bc69e815ad828327ccf10c539&device_id=356330048225461&network=1&ua=GT-S5670&os=2.2.1&version=3.7.1&category_id=0&f_ps=10&s=5&ps=30&pn=1&pcat=2&f=1
HTTP/1.1       499     0       -       Dalvik/1.2.0 (Linux; U; Android
2.2.1; GT-S5670 Build/FROYO)  44      10.034  -

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,232418,232418#msg-232418