PHP Apache crashes while executing a STORED PROCEDURE

Problem

When I execute the following code (I’m calling a stored procedure with 5 IN parameters and 1 OUT parameter)

$conn->query("SET @res = ''");

$mysqli=$conn;
if (!($stmt = $mysqli->prepare("CALL retrieve_matches(5,3, 16, 2, false, @res)"))) {
    echo "Prepare failed: (" . $mysqli->errno . ") " . $mysqli->error;
}

if (!$stmt->execute()) {
    echo "Execute failed: (" . $stmt->errno . ") " . $stmt->error;
}

do {
    if ($res = $stmt->get_result()) { //Apache crash on this call
        printf("---n");
        var_dump(mysqli_fetch_all($res));
        mysqli_free_result($res);
    } else {
        if ($stmt->errno) {
            echo "Store failed: (" . $stmt->errno . ") " . $stmt->error;
        }
    }
} while ($stmt->more_results() && $stmt->next_result());

apache is crashing with error:

AH00428: Parent: child process 9628 exited with status 255 — Restarting.

What I tried

This code is working fine and it’s returning correctly the results:

$conn->query("SET @res = ''");
$res=$conn->query("CALL retrieve_matches(5,3, 16, 2, false, @res)");
var_dump($res->fetch_assoc());

NOTE: The same code above that make Apache crashing is working correctly if I just change the number in input of the stored procedure like:

if (!($stmt = $mysqli->prepare("CALL retrieve_matches(5,6, 16, 2, false, @res)"))) {

Tried from MySQl workbench and both calls are working fine.
I’m using WAMP 64b on a WIN7 Enterprise 64b, I tried with WAMP 32b but got same problem.
I checked windows event and I found httpd.exe is crashing caused by php5ts.dll
If you search for “httpd.exe php5ts.dll” on google you can find a lot of people incountering this problem. But I didn’t find a solution for WAMP…
Tried with AMPPS, exact same problem

PHP Error Log

[10-Jul-2015 15:30:03 UTC] PHP Warning:  PHP Startup: Unable to load dynamic library 'C:/Program Files/wamp/bin/php/php5.5.12/ext/php_ldap.dll' - Impossibile trovare il modulo specificato.

 in Unknown on line 0

[10-Jul-2015 15:30:04 UTC] PHP Warning:  PHP Startup: Unable to load dynamic library 'C:/Program Files/wamp/bin/php/php5.5.12/ext/php_intl.dll' - Impossibile trovare il modulo specificato.

APACHE error log:

[Tue Jul 14 15:02:13.038276 2015] [mpm_winnt:notice] [pid 7044:tid 404] AH00428: Parent: child process 9448 exited with status 255 -- Restarting.
[Tue Jul 14 15:02:13.324305 2015] [mpm_winnt:notice] [pid 7044:tid 404] AH00455: Apache/2.4.9 (Win32) PHP/5.5.12 configured -- resuming normal operations
[Tue Jul 14 15:02:13.329306 2015] [mpm_winnt:notice] [pid 7044:tid 404] AH00456: Apache Lounge VC11 Server built: Mar 16 2014 12:13:13
[Tue Jul 14 15:02:13.329306 2015] [core:notice] [pid 7044:tid 404] AH00094: Command line: 'C:\Program Files\wamp\bin\apache\apache2.4.9\bin\httpd.exe -d C:/Program Files/wamp/bin/apache/apache2.4.9'
[Tue Jul 14 15:02:13.352308 2015] [mpm_winnt:notice] [pid 7044:tid 404] AH00418: Parent: Created child process 3140
[Tue Jul 14 15:02:14.528388 2015] [mpm_winnt:notice] [pid 3140:tid 332] AH00354: Child: Starting 64 worker threads.

I’m really lost here, where should I look for the issue? Thanks very much for your help

EDIT

I realized that the stored procedure “retrieve_matches” is calling different stored procedure in function of the changed value. I debugged the stored procedure “retrieve_standalone” that is the one that make Apache crashing. This procedure is doing select/insert, I checked and the insert are made correctly. BUT inside “retrieve_standalone” I’m using a cursor in a weird way:

declare bNoMoreRows bool default false;
declare tmp_cursor cursor for
    select comp_id from to_match; -- to_match is a temporary table
declare continue handler for not found set bNoMoreRows := true;

if I don’t open the cursor

open tmp_cursor;

everything is working fine!! So I guess I found the issue, now: how can I solve it?

Answer

Apparently there’s a bit of buck passing – i.e. scaricabarile – between PHP guys and MySQLi guys.

What seems to be happening is that MySQLi reacts in an “improper” way, and return an unexpected value (I’d bet a small sum on it being a NULL) to PHP, which duly coredumps. This behaviour is documented and the verdict from PHPland is: “Not a [PHP] bug”. On their side, the MySQLi guys maintain that it’s PHP which is not correctly checking the returned result. And that ‘improper’ results depended on your query anyway.

So I’m going out on a limb and supposing that yours is the same problem of “communication difficulties”, so the problem becomes: “Your query forces MySQLi to drop/reconnect”. Why is that so? Apparently (some) stored procedures require mysqli_multi_query in order to behave properly.

And mysqli_multi_query is not compatible with mysqli_prepare.

So I’d suggest trying without preparing the query, and running it with mysqli_multi_query.

$conn->query("SET @res = ''");
$conn->multi_query("CALL retrieve_matches(5,3, 16, 2, false, @res)");

do {
    if ($result = $conn->store_result()) {
        while ($row = $result->fetch_row()) {
            var_dump($row);
        }
        $result->free();
    }
} while ($conn->more_results() && $conn->next_result());

With this code, your test case gets me, as expected,

array(1) {
  [0] =>
  string(4) "test"
}

Problem

What I tried

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Answer