Run Node.js script from PHP - output is truncated to 512 characters - php

Question

We run node.js CLI script from PHP with Symfony Process.
The script always print whole response as JSON in one line.
The response is somehow truncated on 512 characters.
I only found that xdebug.var_display_max_data => 512 => 512 in php.ini but don't see how this is related.
Adapter > Symfony Process > node script.js
A) Test Node script
from terminal node script $ node user-update.js parameters returns full result in all cases - like 629 chars.
from Symfony Process node script response is truncated to 512 chars.
B) Test Symfony Process
$process = new Process($cmd);
try {
$process->mustRun();
$response = $process->getOutput();
} catch (ProcessFailedException $e) {
$response = $e->getMessage();
}
echo $response;
echo PHP_EOL;
echo strlen($response);
$cmd = 'node user-update.js parameters'; - truncated to 512.
$cmd = 'php -r \'for($i=0; $i<520; $i++){ echo "."; }\''; - does not truncate.
$cmd = 'cat long_one_line.txt'; - print full file. 1650 chars in one line.
C) Try with PHP shell functions
$response = shell_exec($cmd); // response is truncated to 512
system($cmd, $returnVal); // print directly to STDOut, truncated to 512
What could be the cause and solution?
node v7.6.0
PHP 7.1.2

Answer 1

I suspect your process is ending before the buffer can be read by PHP.
As a work-around you can add something like this:
// The `| cat` at the end of this line means we wait for
// cat's process to end instead of node's process.
$process = new Process('node user-update.js parameters | cat');