How to use the hierarchical profiler in PHP

This article gives you a brief introduction to the hierarchical performance analyzer in PHP. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

In PHP, when we need to debug, we usually use memory_get_usage() to check the memory usage. But if you want to see the CPU usage of the current script, there is no ready-made function.

However, PHP also provides us with an extension: XHProf, which is an extension open sourced by FaceBook. It can help us see some performance conditions when the current script is running.

What is XHProf

XHProf is a lightweight layered performance measurement analyzer. During the data collection phase, it tracks the number of calls and measurement data, and displays the arc diagram of the dynamic calls of the program. It calculates exclusive performance metrics such as elapsed run time, CPU compute time, and memory overhead during the reporting, post-processing phase.

Function performance reporting can be terminated by the caller and callee. During the data collection phase, XHProf detects recursive functions through loops in the call graph and avoids loops of recursive calls by assigning unique deep names.

To put it simply, XHProf can collect the system status of many programs for us, and it comes with a set of online chart tools that can provide us with detailed chart information.

Installation

Just download and install the extension package directly from PECL. It is no different from other extension installations. This extension is always being updated and maintained, so it is perfectly supported for the PHP7 version.

Command line usage

xhprof_enable(XHPROF_FLAGS_NO_BUILTINS | XHPROF_FLAGS_CPU | XHPROF_FLAGS_MEMORY);

//xhprof_enable( XHPROF_FLAGS_CPU | XHPROF_FLAGS_MEMORY);

//xhprof_enable( XHPROF_FLAGS_MEMORY);

//xhprof_enable();

for ($i = 0; $i <= 1000; $i++) {
    $a = $i * $i;
}

function test_application(){
    for ($i = 0; $i <= 1000; $i++) {
            $a = $i * $i;
    }
}

test_application();


$xhprof_data = xhprof_disable();

print_r($xhprof_data);

// Array
// (
//     [main()==>test_application] => Array
//         (
//             [ct] => 1
//             [wt] => 16
//             [cpu] => 21
//             [mu] => 848
//             [pmu] => 0
//         )

//     [main()] => Array
//         (
//             [ct] => 1
//             [wt] => 115
//             [cpu] => 115
//             [mu] => 1416
//             [pmu] => 0
//         )

// )

Use xhprof_enable() to enable the analyzer. Its parameters are several constants, which roughly mean to display CPU information, memory information, etc. If there are no parameters, only the two parameters ct and wt will be returned.

Call xhprof_disable() to end the analysis and return the analysis results. The return value includes the running status of the main function, which is the status of our current page test code. There is also the performance of the called function test_application() function. The specific content is:

• ct: Number of calls

• wt: Waiting time to run, milliseconds

• cpu: cpu running time, milliseconds

• mu: memory usage, bytes

• pmu: peak memory usage

Yes, it’s that simple. By calling the two functions, we can see the running status of the current script program, how much memory it occupies, and how much CPU time it consumes. Of course, what is more convenient is that it can also display more detailed information through the web page.

web View result report

First, we need to do some preparation work. The first is to install a graphviz for graphics drawing, the second is to modify the result storage directory of the php.ini file, and the third is to copy the analyzer code in the source code and modify our previous test code.

yum install graphviz

In CentOS system, we can install graphviz directly using yum. Then we specify the output directory for xhprof in the php.ini file.

xhprof.output_dir=/tmp

Next, we need to copy the xhporf_html directory and xhporf_lib directory in the source code file and place them under the project file. Then modify the code to save the results of the performance analysis.

// ..... 上面的代码
$xhprof_data = xhprof_disable();

require 'xhprof_lib/utils/xhprof_lib.php';
require 'xhprof_lib/utils/xhprof_runs.php';

$xhprofRuns = new XHProfRuns_Default();
$runId = $xhprofRuns->save_run($xhprof_data, 'xhprof_test');

echo 'http://192.168.56.102/index.php?run=' . $runId . '&source=xhprof_test';

Then we need to set up the server in xhporf_html, here I use a simple php -S command to run it.

cd xhprof_html/
php -S 0.0.0.0:80

Finally use the link output above to access this page, and you can see the relevant information.

Summary

Today’s test code is just a simple introduction to the use of xhporf. In fact, this extension and this set of analysis tools can be integrated into the framework of our real project. In this way, we can well monitor the running status of the current program in the test environment. However, it is still not recommended to use it in a formal environment. After all, Debug or such performance analysis should not be exposed to the outside world. In a formal environment, we can perform analysis and tuning on the command line.

Test code:

https://github.com/zhangyue0503/dev-blog/blob/master/php/202006/source/%E7%AE%80%E5%8D%95%E5%AD%A6%E4%B9%A0PHP%E4%B8%AD%E7%9A%84%E5%B1%82%E6%AC%A1%E6%80%A7%E8%83%BD%E5%88%86%E6%9E%90%E5%99%A8.php

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