I'm attempting to debug the PayPal review process in Magento. Every time I try to dump the following variable I get a white page:
//the variable declaration:
$shippingAddress = $this->getShippingAddress();
//the dump that breaks the page:
<?php echo '<pre>';print_r($shippingAddress);echo '</pre>'; ?>
I also tried with a variable on the page that was being used for something other than if statements.
//this variable displays results
<?php echo '<pre>';print_r($billingBlock->setShowAsShippingCheckbox(true)->toHtml());echo '</pre>'; ?>
//however, this one does not:
<?php echo '<pre>';print_r($billingBlock);echo '</pre>'; ?>
I was just wondering what might cause my var_dump to break the page? How do I see what is in the object if I can't dump it?
First, PHP never "just white pages". When you get a blank screen, that means PHP's execution has halted fro some reason. However, unless your server has been configured to not log errors, the PHP error log or the Magento exception log should have an error for you.
As far as your specific problem goes, many of Magento's objects contain reference to a large amount of information — and sometimes the references are circular. PHP's var_dump and print_r functions will blindly follow these circular references and attempt to print everything out. This eventually leads to PHP using more memory than is allowed by the memory_limit ini setting, and execution halts.
Most PHP professionals use the xDebug extension to work around this. The xDebug extension has a modified var_dump that will limit the amount of information dumped, which prevents the above memory limit problems. The xdebug.var_display_max_children, xdebug.var_display_max_data, and xdebug.var_display_max_depth ini settings are the ones you'll want to tweak if xDebug's still not helping with the memory limit problem. (some PHP distributions have these set too high initially)
If that's not a possibility, a little caution with your var_dump's can still help.
Use this to figure out the variable type
var_dump(get_class($thing));
If it's a Magento object, use this to see its data keys
var_dump(array_keys($thing->getData()));
And then output individual data members with
var_dump($thing->getData('key_name'));
var_dump($thing->getKeyName()));
A PHP parse and fatal error would produce this. You may want to have a look at your error log.
You could try adding the following lines to the beginning of your php files (just after the opening PHP tag "
ini_set('display_errors',1);
error_reporting(E_ALL);
I am actually trying to monitor a PHP variable (may be as a separate thread but not possible in PHP) and fire a PHP function whenever the value of the variable changes.
eg: lets take a variable $_GLOBALS['foo']=1;
if at any point in the code, the value of $_GLOBALS['foo'] changes to something else, i want to fire a PHP function immediately.
The variable can be anywhere inside a loop or in a function,etc.
Why i want this: I have a variable which stores the last error occured as a text. If the value of the variable changes from "" to something else, i want to trigger an error. My LOGIC may seem a bit strange but this is what i would like to do.
Thanx in advance.
Edit: I tried: How to use monitors in PHP? and How can one use multi threading in PHP applications but does not seem to solve the problem.
The Code (Thought this could solve some of your doubts on my question):
public function addtag($tagarray,$uid,$tagtype="1")
{
$dbobj=new dboperations();
$uiobj=new uifriend();
$tagid=$uiobj->randomstring(30,DB_SOCIAL,SOCIAL_TAG,tag_tagid);
$c=0;
foreach($tagarray as $tags)
{
$c++;
$tagname=$tags["tagname"];
$taguid=$tags["tagid"];
$dbobj->dbinsert("INSERT INTO ".SOCIAL_TAG." (".tag_tagid.",".tag_fuid.",".tag_tuid.",".tag_tagname.",".tag_tagtype.") VALUES
('$tagid','$uid','$taguid','$tagname','$tagtype')",DB_SOCIAL);
}
if($c==0)
{
$lasterror="No tags were added";return "";
}
else
{
return $tagid;
}
}
Here, if i call a error handling function instead of monitoring the variable, it wont be advisable in my case since the error handling function may do any operation like give alert and redirect to a page or any similar operation.
I asked this question cause, i thought what if the script does not reach the line
return "";
It would affect the project's workflow. Thats what i am worried about.
And the variable i was talking about is $lasterror and i have many functions like this where $lasterror is used.
I saw this, so I built this:
https://github.com/leedavis81/vent
Should solve your problem.
There is no built-in way to do this in PHP, and there's no easy way to add it. It doesn't really feel right for the way the language works anyway.
Instead of setting a variable, you could build a custom function that handles the error - or use PHP's built-in error handling functionality using a custom error handler.
Another error handling method which comes close to what you want to do (I think) is exceptions.
I have found that one common reason for the error is an exception being thrown from within an exception handler. I'm quite sure this doesn't happen in the application I'm trying to debug... But I've put all the initialization processing lines at the top of index.php in a try/catch.*
It can apparently also happen because some things cannot be serialized to be stored in a session. At most this application stores arrays into the session (quite a bit), but I'm confident that it doesn't store anything too out of the ordinary in it.
Someone commented that it happened to them because their primary key needed to be CHAR(32) instead of INT(11). The PK's in this app are all INTs.
Other suggestions are that it could be a problem with PHP 5.3.3 fixed in 5.3.6, full disk, and a need to typecast a SimpleXML value. We do happen to be running PHP 5.3.3, but upgrading would have to be a last resort in this case. It hasn't always been doing this.
UPDATE/NOTE: I actually can't reproduce the error myself, only see it happening in the logs, see below paragraph for where I believe the error is happening...
* From the error logs, it seems likely that at least one place it is happening is index.php. I am deducing this only because it is indicated in some entries by a referring URL. The try/catch code is currently only around the "top" initialization portion of the script, below that is mostly the HTML output. There is some PHP code in the output (pretty straightforward stuff though), so I may need to test that. Here is the catch part, which is not producing any output in the logs:
} catch (Exception $e) {
error_log(get_class($e)." thrown. Message: ".$e->getMessage(). " in " . $e->getFile() . " on line ".$e->getLine());
error_log('Exception trace stack: ' . print_r($e->getTrace(),1));
}
Would really appreciate any tips on this!
EDIT: PHP is running as an Apache module (Server API: Apache 2.0 Handler). I don't think there are any PHP accelerators in use, but it could just be that I don't know how to tell. None of the ones listed on Wikipedia are in phpinfo().
As far as I can tell the MPM is prefork. This is the first I'd ever looked into the MPM:
# ./httpd -l
Compiled in modules:
core.c
prefork.c
http_core.c
mod_so.c
The problem
In short you have a exception thrown somewhere, you have no idea where and up until now you could not reproduce the error: It only happens for some people, but not for you. You know that it happens for other people, because you see that in the error logs.
Reproduce the problem
Since you have already eliminated the common reasons you will need to reproduce the error. If you know which parameter will cause the error it should be easy to locate the error.
Most likely it is enough if you know all the POST/GET parameters.
If you can't reproduce with just these, you need to know additional request headers. Such as user agent, accept-encoding,...
If you still can't reproduce, then it becomes very difficult: The error may depend on a state (a session), the current time, the source ip address or the like.
The custom log method
Let's start simple: To get all parameters you can write in the very beginning of the affected php file something like:
file_put_contents("/path/to/some/custom_error_log", date()."\n".print_r(get_defined_vars(), true), FILE_APPEND | LOCK_EX);
Don't forget that the custom_error_log file must be writable to your php application. Then, when the error occurs in the error log, find the corresponding lines in your custom_error_log file. Hopefully there are not to many requests per second so that you can still identify the request. Maybe some additional parameters in the error log like source ip can help you identify the request (if your error log shows that).
From that data, reconstruct a request with the same POST/GET parameters.
The tcpdump method
The next option that is very simple as well, but requires you to have root-access on your target machine is to install tcpflow. Then create a folder, cd into that folder and simply execute (as root) tcpflow "port 80". The option (port 80) is a pcap filter expression. To see all you can do with that, see man pcap-filter. There is a lot what these filter expressions can do.
Now tcpflow will record all tcp connections on port 80, reconstruct the full data exchange by combining the packages belonging to one connection and dump this data to a file, creating two new files per connection, one for incoming data and one for outgoing data. Now find the files for a connection that caused an error, again based on the timestamp in your error log and by the last modified timestamp of the files. Then you get the full http request headers. You can now reconstruct the HTTP request completely, including setting the same accept-encoding, user-agent, etc. You can even pipe the request directly into netcat, replaying the exact request. Beware though that some arguments like a sessionid might be in your way. If php discovers that a session is expired you may just get a redirect to a login or something else that is unexpected. You may need to exchange things like the session id.
Mocking more things
If none of this helps and you can't reproduce the error on your machine, then you can try to mock everything that is hard to mock. For example the source ip adress. This might make some stunts necessary, but it is possible: You can connect to your server using ssh with the "-w" option, creating a tunnel interface. Then assign the offending ip adress to your own machine and set routes (route add host ) rules to use the tunnel for the specific ip. If you can cable the two computers directly together then you can even do it without the tunnel.
Don't foget to mock the session which should be esiest. You can read all session variables using the method with print_r(get_defined_vars()). Then you need to create a session with exactly the same variables.
Ask the user
Another option would be actually ask the user what he was doing. Maybe you can follow the same steps as he and can reproduce.
If none of this helps
If none of that helps... well... Then it gets seriously difficult. The IP-thing is already highly unlikely. It could be a GEO-IP library that causes the error on IPs from a specific region, but these are all rather unlikely things. If none of the above helped you to reproduce the problem, then you probably just did not find the correct request in all the data generated by the custom_log_file-call / tcpflow. Try to increase your chances by getting a more accurate timestamp. You can use microtime() in php as a replacement for date(). Check your webserver, if you can get something more accurate than seconds in your error log. Write your own implementation of "tail", that gives you a more accurate timestamp,... Reduce the load on the system, so that you don't have to choose from that much data (try another time of day, load of users to different servers,...)
circle the problem once you can reproduce
Now once you can reproduce it should be a walk in the park to find the actual cause. You can find the parameter that causes the error by trial and error or by comparing it to other requests that caused an error, too, looking for similarities. And then you can see what this parameter does, which libraries access it, etc. You can disable every component one by one that uses the parameter until you can't reproduce anymore. Then you got your component and can dive into the problem deeper.
Tell us what you found. I am curious ;-).
I had such an error, too. Found out that I returned a sql object in my session class (that was used by the session_handler) instead of returning nothing or at least not the sql object. First look into your _write and _read methods, if you too return some incorrect stuff.
Notice: ... Unknown on line 0 - How to find correct line, it's NOT "line 0"
I realize this question has already been answered, but I'll add this since it may help someone:
I managed to (unintentionally) produce errors without a stack frame from a function which used its own error handler to maintain control of execution while calling a potentially "dangerous" function, like this:
// Assume the function my_error_handler() has been defined to convert any
// PHP Errors, Warnings, or Notices into Exceptions.
function foo() {
// maintain control if danger() crashes outright:
set_error_handler('my_error_handler');
try {
// Do some stuff.
$r = danger();
} catch (Exception $e) {
$r = 'Bad Stuff, Man!';
}
restore error_handler();
return $r;
}
The "untraceable failure" would happen at the end of the program execution if the logic in "Do some stuff" returned from foo() directly, bypassing the call to restore_error_handler(). What I took away from the experience is this:
PHP maintains a stack of error handlers which gets deeper/taller with each call to set_error_handler().
Bad Stuff can happen if you push error handlers onto the stack and don't clean up after yourself before the program exits "normally".
This was a tough bug to isolate - I basically narrowed the problem down to the above function and then stared at it until my eyes bled.
So how would I have tracked this down, knowing what I know now? Since I don't know of any way to inspect the PHP error handler "stack" directly, I'm thinking it might make sense to use a Singleton object to encapsulate all set/restore operations for PHP error handlers. At least then it would be possible to inspect the state of the Singleton before exiting the program normally, and if "dangling" error handlers are detected to generate a sensible failure/warning message before PHP freaks out.
Instead of wrapping code in a try/catch block, what happens when you register an exception handler? Clearly your try/catch block is not catching the exception, thus resulting in the errors logged to Apache. By registering a handler, you can be sure any uncaught exception is handled.
Also, if you're using namespaces in your application, make sure you write \Exception in your catch block (or include the Exception class via a use statement).
This may be a little late but one issue I discovered when moving a site from a local to a remote server. I was using Concrete5 cms had developed my site locally(windows 8 in xampp) and then uploaded to a remote server running Cent 0S
Windows mysql by default is case insensitive and created a lower case database. Once this was uploaded to the remote server I received the "Exception thrown without a stack frame in Unknown on line 0?"
I then corrected the database tables case and my site started working again.
For us, this error was due to inadvertently serializing SimpleXML objects.
If you are using SimpleXML objects with 5.3.3, make sure you are are casting the node values to whatever you need (e.g. string) if you are serializing the values in the session.
Before:
$token = $response->Token->Value;
/* token saved in session, results in line 0 error */
After:
$token = (string) $response->Token->Value;
/* token saved in session, no error */
I had completely the same error. A very spacial case: if you connect an unnamed function (closure) hook to an object instance's hook point. After that you try to serialize this object.
I had the same error after filling the Illuminate Eloquent model's Fillable property incorrectly. Note the last 3 elements of the array, one is missing a coma.
protected $fillable = [
'budget',
'routestatus' ,
'userroutenumber'
'totalmovingseconds',
'totalidleseconds'
];
I had the same error, it appeared upgrading server from centos 5 to centos 6 and downgrading PHP from 5.4 to 5.3. Actual issue was PHP apc, not configured properly. Check your APC. I was using Symfony2, so you might find some help at Symfony Unable to allocate memory for pool
one simple way to produce this error is an old server with register_globals = On. then you only need two lines of code:
<?php
$_SESSION["my_var"] = "string";
$my_var = new MyClass(); //could be any class, i guess
?>
as soon as you reload this page once, you'll get the Exception thrown without a stack frame in Unknown on line 0 - error. seems like there is a conflict between the instance of the class and the (session) variable.
at least this is how i got this annoying error which is so hard to debug.
This problem occurred for me when I changed the namespace on a few Symfony bundles. Deleting the files in the the symfony cache directory fixed the issue.
Likely you have a corrupt/inconsistent table in the database. Try dumping the database. If you get a error that's the time. Repair that table and the issue should go away.
It is for this reason why clean install works. The clean install is just that clean.
mysqlcheck should work but if it does not show and issue still do above.
This seems to have been discussed quite a bit. I've tried several things I've found, but no luck.
I have a "hacky" cache built that stores objects received from XML calls. The XML calls proved to take too long on page loads, so a user can push a button in the admin to rebuild the cache. The cache routine keeps dying with a memory allocation error.
I know this is a very vague question, but I'm not sure it would help to post a big section of code either.
I am "unsetting" every varaible after I finish using it. I'm calling gc_collect_cycles() which doesn't seem to do anything at all.
I have two anonymous functions that get called over an over....could these be the culprits?
What should I be looking for? Would doing a sleep() help at all?
Code Edit
Here is the code: http://pastebin.com/8M1Dk73E
On line 79 of the pastebin code, I'm calling gc_collect_cycles. Not sure if that is a good place to put it or not.
I am using foreach loops instead of for loops, which I know makes a huge difference with objects being copied, but I would think if I unset the variables it should work the same even if the execution time is longer.
Well, I'm at a loss, so any thoughts would be helpful.
This may be related to gc_collect_cycles. In some php versions and in some loop conditions this function will fail to collect the cycle: For instance, see: https://bugs.php.net/bug.php?id=53803 and https://bugs.php.net/bug.php?id=53071
If you can, try updating PHP to 5.3.9 and see if it works. If not, try dropping the collection and relying exclusively on unset() (keeping in mind that unsetting global variable only destroys it within the function) and you'll need to unset it from the $GLOBALS array if you want to destroy it everywhere.
If you're still stuck, try tracking your memory carefully as it moves through the loop by using memory_get_usage() with a note after anything that should require or release memory. Something like:
try{
$result = $client->GetListingPhotosWithFullPath(array('mlsID'=>$bid->MlsID, 'mlsNumber'=>$bid->MlsNumber));
echo "Got Photos with Full Path on line ".__LINE__." - Now using ".memory_get_usage()."<br />\n";
$listing->photos = $result->GetListingPhotosWithFullPathResult->Photo;
echo "Setting $listing->photos on ".__LINE__." - Now using ".memory_get_usage()."<br />\n";
(isset($opt->comet)) ? $msg("Photos received.") : '';
//Memory Cleanup
unset( $result );
echo "\$result unseet on ".__LINE__." - Now using ".memory_get_usage()."<br />\n";
}
This should let you see where your cycle is building up memory.
I'm trying to see what is inside all the objects of the Magento system, but when I try to var_dump the $_links variable (containing all information needed for rendering the links in the header of every page) from inside the top links template, my server responds with a 500 error. Anyone know why?
Dumps of Magento objects get a bit messy, even if there isn't recursion there is all the EAV and cache stuff. When you have an array you'll need to dump them individually:
foreach ($_links as $object) {
var_dump($object->debug());
}
It's likely a memory error. Magento's object can be huge, and the default var_dump implementation in PHP isn't that smart about some of the circular references.
Install xDebug is a must. With xDebug, the var_dump function gets a lot smarter, and the memory limit exhausted errors mostly go away.
Magento is a huge memory hog. Most likely, you're running out of available memory.
Instead of var dumping the object itself, dump the objects data using its ->toArray() method. Note: all Mage_ objects inherit this method.
HTTP 500 errors will occur in scenarios like this when PHP spewed an error, and you did not configure your setup to display it to the user.
Look in your error log (something like /var/lib/httpd/log/error_log) to find out what's actually going on.
Possibilities include:
Syntax error
Headers already sent before output
Memory exhaustion from printing huge variable
In most of cases it's because $_links variable contains a lot of huge nested objects. Try the xDebug extension for PHP - it allows to tune var_dump output to limit nesting level and amount of displaying data.
$_link variable consist huge number of objects inside, we needs to debug to print the object
print_r($_link->debug());
(or)
var_dump($_link->debug());
I solve my var_dump(array) result in a 500 error in Magento2 issue as below(May be someone help)
//app/code/MyCompany/Shipping/view/adminhtml/templates/order/view/items.phtml
foreach ($_items as $_item):
echo "<pre>";
var_dump($_item->debug());
echo "</pre>";
Sample Output: