PHP Built-In Server Exiting with SIGSEGV / Wordpress

Question

Developing a wordpress blog locally, my PHP server is dying with SIGSEGV half-way through rendering the page.

Here's my startup script: sudo php -S 127.0.0.1:80 -t ../reece-blog-local

I wish I could provide more details, but I can't seem to get any information out of PHP about this. The only reason I know it's exiting with SIGSEGV is that I'm running this process with foreman, otherwise the process just exits silently.

There does not seem to be a particular line of code that's making it break, I can track down the area of the error based on the HTML that's managed to render before exit, and I can stick in a few echo "Hello, world!"s and it breaks on any given one of them.

Notes:

• server was working fine until I upgraded to Mavericks, so thinking that something there could be interfering.
• confirmed this happens when CURLing any URL, so likely rules out this being an issue with serving static files.
• not exhausting my memory limit

How can I further debug this issue, in lieu of any specific errors output by PHP?

Answer 1

PHP server will exit with segmentation fault (SIGSEGV) error in the event of infinite recursion, e.g.:

function test() {
    test();
}

If the output is buffered and you use echo to debug an error like this, the error may appear to occur in strange places (hence why it would seem to break on a line like echo "Hello, world!";)

Instead, you can use error_log($yourMessage, 4); to output a message to the console. This helped track down the error for me (though from reading around it seems XDebug may be the preferred solution for finding errors like this.)

For what it's worth, here's effectively how I had infinite recursion:

class TheParent {
  public function __call($method, $args) {
    return call_user_func_array(array($this, $method), $args);
  }
}

class TheChild extends TheParent {
  protected function thisIsOkay() {
    echo 'yay';
  }
  private function sigsegv() {
    echo 'no';
  }
}

$c = new TheChild;
$c->thisIsOkay();
$c->sigsegv();

If we attempt to call a private function in TheChild, __call will be invoked, attempt to access the private function, invoking __call, etc.