truncated output with gzip, large files and slow rate

[James Lee]

Hello,

nginx is truncating output with the following:
  + gzip on
  + compressed size greater than 100k (approx)
  + client downloads at a slow rate


*** Steps to reproduce ***

nginx.conf:

events {
}
http {
     types {
         text/plain txt;
     }
     gzip on;
     gzip_types text/plain;
     server {
         listen 80 default_server;
         server_name _;
         root /path/to/root;
     }
}


Create a test file that is larger than 100k compressed:

$ head -1000 /dev/random > /path/to/root/test.txt


Request exhibiting failure:

$ curl -H "Accept-Encoding: gzip" --limit-rate 50k localhost/test.txt |  
gzcat | cksum
   % Total    % Received % Xferd  Average Speed   Time    Time     Time   
Current
                                  Dload  Upload   Total   Spent    Left   
Speed
100  180k    0  180k    0     0   2966      0 --:--:--  0:01:02  
--:--:--     0
curl: (18) transfer closed with outstanding read data remaining

gzcat: stdin: unexpected end of file
649550918       184260


and with wget:

$ wget --header "Accept-Encoding: gzip" --limit-rate=50k -O /dev/stdout  
localhost/test.txt | gzcat | cksum

--2012-04-15 11:27:04--  http://localhost/test.txt
Resolving localhost (localhost)... 127.0.0.1, ::1
Connecting to localhost (localhost)|127.0.0.1|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/plain]
Saving to: `/dev/stdout'

     [                                <=>     ] 184,330     --.-K/s   in 61s

2012-04-15 11:28:06 (2.96 KB/s) - `/dev/stdout' saved [184330]


gzcat: stdin: unexpected end of file
649550918       184260




Some variants showing success (correct size and cksum) by avoiding one of  
compression or limit-rate:

$ curl -H "Accept-Encoding: gzip" localhost/test.txt | gzcat | cksum
   % Total    % Received % Xferd  Average Speed   Time    Time     Time   
Current
                                  Dload  Upload   Total   Spent    Left   
Speed
100  235k    0  235k    0     0  5970k      0 --:--:-- --:--:-- --:--:--  
6370k
2871747365      241269


$ curl --limit-rate 50k localhost/test.txt | cksum
   % Total    % Received % Xferd  Average Speed   Time    Time     Time   
Current
                                  Dload  Upload   Total   Spent    Left   
Speed
100  235k  100  235k    0     0  47700      0  0:00:05  0:00:05 --:--:--  
55650
2871747365      241269



There are also failures with major web browsers including Firefox 11.0,  
MSIE 9.0 and Safari.

No error is reported by nginx.  The http return code and logged code is  
200.  The only clue in the server is the sent size reported is smaller  
than the expected compressed size.



*** Other information ***

nginx 1.1.19
Solaris 10 u10




James.