[Nginx return empty data, while header is 200 OK]

I have a problem with my rest service as below:

 

 1. a server with NGinx, PHP-FPM, provide rest service: example: http://example.com/rest.php, this link only show content: 1001:Successfully

 2. another server using curl call this rest service to get content. With happy case, it must get content from rest service is 1001:Successfully. But problem happen -

In most case it get content ok, but sometimes I get empty content while http_status is 200 ok. I don't know what is happening. Could anyone help me?

 

Empty content and CURL debug information as below:

 

    '* About to connect() to example.com port 80 (#0)

    *   Trying xxx.xxx.xxx.xxx...

    * connected

    * Connected to example.com (xxx.xxx.xxx.xxx) port 80 (#0)

    > GET /rest.php HTTP/1.1

    User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; rv:1.7.3) Gecko/20041001 Firefox/0.10.1

    Host: example.com

    Accept: */*

    Accept-Encoding: deflate, gzip

    

    < HTTP/1.1 200 OK

    < Server: XXX

    < Date: Mon, 12 May 2014 12:58:17 GMT

    < Content-Type: text/html

    < Transfer-Encoding: chunked

    < Connection: keep-alive

    < 

    * Connection #0 to host channel.ssgroup.vn left intact

    * Closing connection #0

    ',

    )

[Problem with php debugger]

I have a problem with install php debugger on virtual Linux web server. When i install debugger 3.6 and config apache enable debugger, the server become slowly. When error happen, it seem loop, the webpage can't response. I don't know why?Please help me.