PHP: Long strings, json_encode, var_dump and echo

Question

I noticed that the application I was developing was breaking, I managed to narrow it down to this problem (I have set up a test case for it):

ini_set("display_errors", "1");
error_reporting(E_ALL);

error_log("[test] Memory limit: " . ini_get('memory_limit'));
error_log("[test] Max Execution Time: " . ini_get('max_execution_time'));

$testArray = array("abcdefghijklmnotuv..... 786998 characters later...ijklmEND");
$json = json_encode($testArray);

var_dump($json);
// echo($json);

error_log("[test] Memory: ".memory_get_usage()."B");

When I var_dump the variable $json, I get the correct output:

string(786998) "["abcdefghijklm....ijklmEND"]"

When I echo the variable $json, you can very briefly see something appear on the screen but then it disappears, the end response seems to be NULL.

If I repeat the above with a string instead of an array the same thing happens.

If I repeat the above with a string AND omit the json_encode step everything behaves as expected, the results of var_dump and echo are correct.

During the entire process there are no errors output in the error log, my memory limits and max execution times are also okay:

[test] Memory limit: 256M
[test] Max Execution Time: 30
[test] Memory: 2134296B

Any ideas?

A little information on my application:

In a nutshell there are two servers. Server A sends a HTTP request to server B, server B processes the request and sends the response back to server A. The response is always a JSON encoded array. If one of the values of the array in the response is too long server A receives a NULL response.

Answer 1

It turns out the problem wasn't to do with server B, it was server A.

Server A is implemented in Java using the Netty API.

The HTTP response was too long and it was being chunked and I didn't have a HttpChunkAggregator in my pipeline, once I added it in everything was fine.

ClientBootstrap cb = new ClientBootstrap(cf);

cb.getPipeline().addLast("codec", new HttpClientCodec());
cb.getPipeline().addLast("chunkaggregator", new HttpChunkAggregator(1048576));
cb.getPipeline().addLast("inflater", new HttpContentDecompressor());
cb.getPipeline().addLast("handler", new OutboundHandler());

I did check the browser source externally and the code was there, thank you for your comments they did lead me in the right direction!