Print PHP Call Stack

Question

I'm looking for a way to print the call stack in PHP.

Bonus points if the function flushes the IO buffer.

possible duplicate of [How can I get PHP to produce a backtrace upon errors?](http://stackoverflow.com/questions/1159216/how-can-i-get-php-to-produce-a-backtrace-upon-errors) — Gordon, Nov 17 '11 at 09:22
if it is ordered by quality, then that thread is the duplicated one :D — Jacky Supit, Nov 18 '22 at 07:19

score 704 · Answer 1 · edited Feb 20 '17 at 18:38

704

More readable than debug_backtrace():

$e = new \Exception;
var_dump($e->getTraceAsString());

#2 /usr/share/php/PHPUnit/Framework/TestCase.php(626): SeriesHelperTest->setUp()
#3 /usr/share/php/PHPUnit/Framework/TestResult.php(666): PHPUnit_Framework_TestCase->runBare()
#4 /usr/share/php/PHPUnit/Framework/TestCase.php(576): PHPUnit_Framework_TestResult->run(Object(SeriesHelperTest))
#5 /usr/share/php/PHPUnit/Framework/TestSuite.php(757): PHPUnit_Framework_TestCase->run(Object(PHPUnit_Framework_TestResult))
#6 /usr/share/php/PHPUnit/Framework/TestSuite.php(733): PHPUnit_Framework_TestSuite->runTest(Object(SeriesHelperTest), Object(PHPUnit_Framework_TestResult))
#7 /usr/share/php/PHPUnit/TextUI/TestRunner.php(305): PHPUnit_Framework_TestSuite->run(Object(PHPUnit_Framework_TestResult), false, Array, Array, false)
#8 /usr/share/php/PHPUnit/TextUI/Command.php(188): PHPUnit_TextUI_TestRunner->doRun(Object(PHPUnit_Framework_TestSuite), Array)
#9 /usr/share/php/PHPUnit/TextUI/Command.php(129): PHPUnit_TextUI_Command->run(Array, true)
#10 /usr/bin/phpunit(53): PHPUnit_TextUI_Command::main()
#11 {main}"

edited Feb 20 '17 at 18:38

pmaruszczyk

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answered Aug 12 '11 at 11:27

Tobias Cudnik

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67

Damn, this is so much better, why couldn't they make this the default output for debug_print_backtrace()? Could have added a boolean parameter "returnTrace" for those who want it in a variable, not echoed, and it would have been perfect! – jurchiks May 21 '13 at 08:28
1

I dont know how many months i been trying to figure out how to do that never thought it would work – WojonsTech Oct 22 '13 at 18:54
This solution also appears to take less memory than capturing the output of debug_backtrace() as an array and then printing it using print_r(), which is what I had been doing until I saw this! – Peter Nov 13 '13 at 12:38
5

I was looking for a way to limit `debug_backtrace` to only return the first level in the stacktrace - this solution does the work for me. Thank you! – ankr Oct 20 '14 at 14:41
But seems to cut off the messages – Andrew Oct 11 '15 at 18:50
4

@Andrew `print_r` will retain all the messages. – mopo922 Jun 22 '16 at 02:55
$e = new \Exception; echo "
```
";
var_dump($e->getTraceAsString());
echo "
```
"; die("test");
– Claudiu Creanga Jul 14 '16 at 19:08
I dont understand this, where do I put my function or variable I want to backtrace? – veritaS Oct 16 '18 at 14:27
So much better and clean. – Riz Nov 02 '18 at 17:36
$call_stack = explode('#', $e->getTraceAsString()); to get it in a nice array – Maciej Krawczyk Jul 24 '19 at 14:02
The best solution by far. – mrodo Oct 22 '21 at 10:08

Pascal MARTIN · Accepted Answer · 2010-04-15T10:52:09.097

140

If you want to generate a backtrace, you are looking for debug_backtrace and/or debug_print_backtrace.

The first one will, for instance, get you an array like this one (quoting the manual) :

array(2) {
[0]=>
array(4) {
    ["file"] => string(10) "/tmp/a.php"
    ["line"] => int(10)
    ["function"] => string(6) "a_test"
    ["args"]=>
    array(1) {
      [0] => &string(6) "friend"
    }
}
[1]=>
array(4) {
    ["file"] => string(10) "/tmp/b.php"
    ["line"] => int(2)
    ["args"] =>
    array(1) {
      [0] => string(10) "/tmp/a.php"
    }
    ["function"] => string(12) "include_once"
  }
}

They will apparently not flush the I/O buffer, but you can do that yourself, with flush and/or ob_flush.

(see the manual page of the first one to find out why the "and/or" ;-) )

edited Apr 15 '10 at 10:52

answered Sep 14 '09 at 18:25

Pascal MARTIN

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7

this regularly makes my php run out of memory. I recommend Tobiasz' solution. – peedee Jul 16 '15 at 09:19
If you find it hard to read/understand, I also recommend Tobiasz' solution – ViliusL Sep 19 '18 at 07:05
2

@peedee all it takes is to provide one of the optional `DEBUG_BACKTRACE_IGNORE_ARGS` parameter; that makes them functionally equivalent to `(new \Exception())->getTraceAsString()` – Nov 06 '18 at 14:40

score 51 · Answer 3 · answered Mar 14 '16 at 17:17

51

Strange that noone posted this way:

debug_print_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS);

This actually prints backtrace without the garbage - just what method was called and where.

answered Mar 14 '16 at 17:17

AbstractVoid

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2

Indeed, really equivalent to the main voted solution, and shorter. Thanks – Bruno Duyé Dec 21 '16 at 16:30
1

Where does this print to? – MrDysprosium Aug 22 '21 at 18:46

Sydwell · Answer 4 · 2011-10-24T15:44:22.223

49

To log the trace

$e = new Exception;
error_log(var_export($e->getTraceAsString(), true));

Thanks @Tobiasz

edited Oct 24 '11 at 15:44

answered Oct 24 '11 at 15:30

Sydwell

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score 39 · Answer 5 · edited Aug 08 '12 at 09:43

Backtrace dumps a whole lot of garbage that you don't need. It takes is very long, difficult to read. All you usuall ever want is "what called what from where?" Here is a simple static function solution. I usually put it in a class called 'debug', which contains all of my debugging utility functions.

class debugUtils {
    public static function callStack($stacktrace) {
        print str_repeat("=", 50) ."\n";
        $i = 1;
        foreach($stacktrace as $node) {
            print "$i. ".basename($node['file']) .":" .$node['function'] ."(" .$node['line'].")\n";
            $i++;
        }
    } 
}

You call it like this:

debugUtils::callStack(debug_backtrace());

And it produces output like this:

==================================================
 1. DatabaseDriver.php::getSequenceTable(169)
 2. ClassMetadataFactory.php::loadMetadataForClass(284)
 3. ClassMetadataFactory.php::loadMetadata(177)
 4. ClassMetadataFactory.php::getMetadataFor(124)
 5. Import.php::getAllMetadata(188)
 6. Command.php::execute(187)
 7. Application.php::run(194)
 8. Application.php::doRun(118)
 9. doctrine.php::run(99)
 10. doctrine::include(4)
==================================================

['file' and 'line' are not always present in $node](http://stackoverflow.com/a/6643478/210336) — Matthijs Wessels, Jul 11 '16 at 16:30
Why not add the parameters to those function calls? Class name is also available for class member functions. You could dd little more code, then out this on GitHub. — Mawg says reinstate Monica, Oct 31 '20 at 09:05

score 10 · Answer 6 · answered Mar 15 '13 at 18:46

If you want a stack trace which looks very similar to how php formats the exception stack trace than use this function I wrote:

function debug_backtrace_string() {
    $stack = '';
    $i = 1;
    $trace = debug_backtrace();
    unset($trace[0]); //Remove call to this function from stack trace
    foreach($trace as $node) {
        $stack .= "#$i ".$node['file'] ."(" .$node['line']."): "; 
        if(isset($node['class'])) {
            $stack .= $node['class'] . "->"; 
        }
        $stack .= $node['function'] . "()" . PHP_EOL;
        $i++;
    }
    return $stack;
}

This will return a stack trace formatted like this:

#1 C:\Inetpub\sitename.com\modules\sponsors\class.php(306): filePathCombine()
#2 C:\Inetpub\sitename.com\modules\sponsors\class.php(294): Process->_deleteImageFile()
#3 C:\Inetpub\sitename.com\VPanel\modules\sponsors\class.php(70): Process->_deleteImage()
#4 C:\Inetpub\sitename.com\modules\sponsors\process.php(24): Process->_delete()

Brad, that solution doesn't remove the last item from the stack trace so you don't show the trace item caused by the new Exception — TroySteven, Sep 12 '19 at 15:05

score 8 · Answer 7 · answered Sep 14 '09 at 18:26

8

var_dump(debug_backtrace());

Does that do what you want?

answered Sep 14 '09 at 18:26

brettkelly

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score 6 · Answer 8 · answered Sep 14 '09 at 18:25

6

See debug_print_backtrace. I guess you can call flush afterwards if you want.

answered Sep 14 '09 at 18:25

Martin Geisler

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score 6 · Answer 9 · answered Jan 06 '15 at 09:55

phptrace is a great tool to print PHP stack anytime when you want without installing any extensions.

There are two major function of phptrace: first, print call stack of PHP which need not install anything, second, trace php execution flows which needs to install the extension it supplies.

as follows:

$ ./phptrace -p 3130 -s             # phptrace -p <PID> -s
phptrace 0.2.0 release candidate, published by infra webcore team
process id = 3130
script_filename = /home/xxx/opt/nginx/webapp/block.php
[0x7f27b9a99dc8]  sleep /home/xxx/opt/nginx/webapp/block.php:6
[0x7f27b9a99d08]  say /home/xxx/opt/nginx/webapp/block.php:3
[0x7f27b9a99c50]  run /home/xxx/opt/nginx/webapp/block.php:10

I like the memory address are shown here.. This can be helpful — Richard Tyler Miles, Feb 15 '19 at 18:34

score 4 · Answer 10 · answered Sep 20 '17 at 09:46

4

Walltearer's solution is excellent, particularly if enclosed in a 'pre' tag:

<pre>
<?php debug_print_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS); ?>
</pre>

- which sets out the calls on separate lines, neatly numbered

answered Sep 20 '17 at 09:46

Geoff Kendall

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score 4 · Answer 11 · answered Oct 13 '21 at 14:09

4

If one is just interested in the files called - you can use the following:

print_r(array_column(debug_backtrace(),'file'));

Likewise you can replace file with a different key just to see that data.

answered Oct 13 '21 at 14:09

Antony

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score 3 · Answer 12 · answered Sep 14 '09 at 18:26

3

Use debug_backtrace to get a backtrace of what functions and methods had been called and what files had been included that led to the point where debug_backtrace has been called.

answered Sep 14 '09 at 18:26

Gumbo

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score 2 · Answer 13 · answered Mar 11 '16 at 18:36

2

please take a look at this utils class, may be helpful:

Usage:

<?php
/* first caller */
 Who::callme();

/* list the entire list of calls */
Who::followme();

Source class: https://github.com/augustowebd/utils/blob/master/Who.php

answered Mar 11 '16 at 18:36

augustowebd

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score 1 · Answer 14 · answered Sep 14 '09 at 18:25

1

debug_backtrace()

answered Sep 14 '09 at 18:25

pix0r

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score 1 · Answer 15 · answered Sep 14 '09 at 18:26

1

You might want to look into debug_backtrace, or perhaps debug_print_backtrace.

answered Sep 14 '09 at 18:26

Rob

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score 1 · Answer 16 · answered Feb 15 '19 at 18:08

I have adapted Don Briggs's answer above to use internal error logging instead of public printing, which may be your big concern when working on a live server. Also, added few more modifications like option to include full file path instead of basic name (because, there could be files with same name in different paths), and also (for those who require it) a complete node stack output:

class debugUtils {
    public static function callStack($stacktrace) {
        error_log(str_repeat("=", 100));
        $i = 1;
        foreach($stacktrace as $node) {
            // uncomment next line to debug entire node stack
            // error_log(print_r($node, true));
            error_log( $i . '.' . ' file: ' .$node['file'] . ' | ' . 'function: ' . $node['function'] . '(' . ' line: ' . $node['line'] . ')' );
            $i++;
        }
        error_log(str_repeat("=", 100));
    } 
}

// call debug stack
debugUtils::callStack(debug_backtrace());

Print PHP Call Stack

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