Deploying PHP 7

PHP Meetup

Mexico City

Sept.21, 2016

http://talks.php.net/unam

Rasmus Lerdorf
@rasmus

✔ engine improvements

100%+ performance gain on most real-world applications
Lower memory usage, sometimes drastically lower

JIT?

Improve CPU cache usage

Step 1: Decrease overall data
Step 2: Better data locality and less indirections
Step 3: Save the world!

zval size reduced from 24 to 16 bytes
Hashtable size reduced from 72 to 56 bytes
Hashtable bucket size reduced from 72 to 32 bytes
Immutable array optimization

$a = [];
for($i=0; $i < 100000;$i++) {
    $a[] = ['abc','def','ghi','jkl','mno','pqr'];
}
echo memory_get_usage(true);

// PHP 5.x  109M
// PHP 7.0   42M no opcache
// PHP 7.0    6M with opcache enabled

New memory allocator similar to jemalloc
Faster hashtable iteration API
Array duplication optimization
PCRE JIT enabled by default
Precomputed string hashes
Fast ZPP (ZendParseParameters) implementation
Faster stack-allocated zvals (instead of heap)
Optimized VM calling
Global register variables with gcc 4.8+
plus hundreds of micro-optimizations

HugePage support in Opcache

./configure --enable-huge-code-pages

opcache.memory_consumption=256
opcache.huge_code_pages=1

% sysctl -w vm.nr_hugepages=256
% service php-fpm start
% cat /proc/meminfo | grep Huge
HugePages_Total:     256
HugePages_Free:      231
HugePages_Rsvd:      119
HugePages_Surp:        0
Hugepagesize:       2048 kB

JIT?

GCC Feedback-Directed Optimization (FDO)

$ make clean
$ make -j8 prof-gen
...
$ sapi/cgi/php-cgi -T 1000 /var/www/wordpress/index.php > /dev/null
$ make prof-clean
$ make -j8 prof-use

✔ engine improvements

100%+ performance gain on most real-world applications
Lower memory usage, sometimes drastically lower

✔ Exceptions on Fatals

function call_method($obj) {
    $obj->method();
}
call_method(null);

Fatal error: Uncaught Error: Call to a member function method() on null in file:2
Stack trace:
#0 file(4): call_method(NULL)
#1 {main}
  thrown in file on line 2

try {
    call_method(null);
} catch (Error $e) {
    echo "Caught Exception: {$e->getMessage()}\n";
}

Caught Exception: Call to a member function method() on null

PHP 7 Exception Hierarchy

Throwable
➥ Exception implements Throwable
➥ Error implements Throwable
➥ TypeError extends Error
➥ ParseError extends Error

✔ Return Types

function get_config(): array {
    return 42;
}
get_config();

Fatal error: Uncaught TypeError: Return value of get_config() must be
of the type array, integer returned in file:2
Stack trace:
#0 file(4): get_config()
#1 {main}
  thrown in file on line 2

✔ Coercive Scalar Types

function logmsg(string $msg, int $level, float $severity) {
    var_dump($msg);      // string(1) "1"
    var_dump($level);    // int(2)
    var_dump($severity); // float(3)
}
logmsg(1, "2.5 bananas", 3);

Notice: A non well formed numeric value encountered in file on line 2

✔ Strict Scalar Types

declare(strict_types=1);
...
logmsg(1, "2.5", 3);

Fatal error: Uncaught TypeError: Argument 1 passed to logmsg() must be of the
type string, integer given, called in file on line 7 and defined in file:3
Stack trace:
#0 file(7): logmsg(1, '2.5', 3)
#1 {main}
  thrown in file on line 2

✔ Anonymous Classes

return new class($controller) implements Page {
    public function __construct($controller) {
        /* ... */
    }
    /* ... */
};

class MyObject extends MyStuff {
    public function getInterface() {
        return new class implements MyInterface {
            /* ... */
        };
    }
}

✔ Coalesce Operator

$a = NULL;
$b = 0;
$c = 2;

echo $a ?? $b; // 0
echo $c ?? $b; // 2
echo $a ?? $b ?? $c; // 0
echo $a ?? $x ?? $c; // 2

✔ Spaceship Operator

function cmp_php5($a, $b) {
    return ($a < $b) ? -1 : (($a >$b) ? 1 : 0);
}

function cmp_php7($a, $b) {
    return $a <=> $b;
}

✔ Removal of many deprecated features
(Your PHP4 code will break!)

- ext/ereg (use ext/pcre instead)
- preg_replace() eval modifier (use preg_replace_callback() instead)
- ext/mysql (use ext/mysqli or ext/pdo_mysql instead)
- Assignment of new by reference
- Scoped calls of non-static methods from incompatible $this context

- dl() in php-fpm
- set_magic_quotes_runtime() and magic_quotes_runtime()
- set_socket_blocking() (use stream_set_blocking() instead)
- mcrypt_generic_end() (use mcrypt_generic_deinit() instead)
- mcrypt_ecb, mcrypt_cbc, mcrypt_cfb and mcrypt_ofb 
  (use mcrypt_encrypt() and mcrypt_decrypt() instead)
- datefmt_set_timezone_id() and IntlDateFormatter::setTimeZoneID() 
  (use datefmt_set_timezone() or IntlDateFormatter::setTimeZone() instead)

- xsl.security_prefs (use XsltProcessor::setSecurityPrefs() instead)
- iconv.input_encoding, iconv.output_encoding, iconv.internal_encoding,
  mbstring.http_input, mbstring.http_output and mbstring.internal_encoding
  (use php.input_encoding, php.internal_encoding and php.output_encoding instead)

- $is_dst parameter of the mktime() and gmmktime() functions
- # style comments in ini files (use ; style comments instead)
- String category names in setlocale() (use LC_* constants instead)
- Unsafe curl file uploads (use CurlFile instead)
- PDO::PGSQL_ATTR_DISABLE_NATIVE_PREPARED_STATEMENT driver option 
  (use PDO::ATTR_EMULATE_PREPARES instead)
- CN_match and SNI_server_name stream context option (use peer_name instead)

✔ New reserved words:

bool
int
float
string
null
false
true
resource
object
mixed
numeric

✔ 64-bit integer support on Windows

✔ Cleanup edge-case integer overflow/underflow

✔ Support for strings with length >= 2^31 bytes in 64 bit builds.

✔ Parse error on invalid numeric literals

$mask = 0855;  // Parse error: Invalid numeric literal

✔ Uniform variable syntax

// left-to-right
$this->$belongs_to['column']
// vs.
$this->{$belongs_to['column']}

// support missing combinations of operations
$foo()['bar']()
[$obj1, $obj2][0]->prop
getStr(){0}
 
// support nested ::
$foo['bar']::$baz
$foo::$bar::$baz
$foo->bar()::baz()
 
// support nested ()
foo()()
$foo->bar()()
Foo::bar()()
$foo()()
 
// support operations on arbitrary (...) expressions
(...)['foo']
(...)->foo
(...)->foo()
(...)::$foo
(...)::foo()
(...)()
 
// two more practical examples for the last point
(function() { ... })()
($obj->closure)()
 
// support all operations on dereferencable scalars
// (not very useful)
"string"->toLower()
[$obj, 'method']()
'Foo'::$bar

✔ Unicode Codepoint Escape Syntax

echo "\u{202E}Right-to-left text";

echo " \u{26BD}";

‮Right-to-left text ⚽

✔ ICU IntlChar class added to intl extension

✔ CSPRNG

$int   = random_int(-500, 500);
$bytes = random_bytes(10);

var_dump( $int );
var_dump( bin2hex($bytes) );

int(472)
string(20) "7be20b35ed8a443e2411"

Top-5 Things that might bite you

For the full list see

php.net/migration70

Left-to-right semantics for complicated expressions

$$foo['bar']['baz'] // interpreted as ($$foo)['bar']['baz']
$foo->$bar['baz']   // interpreted as ($foo->$bar)['baz']
$foo->$bar['baz']() // interpreted as ($foo->$bar)['baz']()
Foo::$bar['baz']()  // interpreted as (Foo::$bar)['baz']()

To restore the previous behaviour add explicit curly braces:

${$foo['bar']['baz']}
$foo->{$bar['baz']}
$foo->{$bar['baz']}()
Foo::{$bar['baz']}()

Detection: phan or unit test failures

Removed support for /e (PREG_REPLACE_EVAL) modifier

echo preg_replace('/:-:(.*?):-:/e', '$this->pres->\\1', $text);

Change to:

echo preg_replace_callback(
  '/:-:(.*?):-:/', 
  function($matches) {
    return $this->pres->{$matches[1]}; // Careful!
  },
  $text);

Detection: grep, warnings in logs or unit test failures

$HTTP_RAW_POST_DATA global removed

if (empty($GLOBALS['HTTP_RAW_POST_DATA']) &&
    strpos($_SERVER['CONTENT_TYPE'], 'www-form-urlencoded') === false) {
    $GLOBALS['HTTP_RAW_POST_DATA'] = file_get_contents("php://input");
}

Detection: grep, warnings in logs or unit test failures

session.lazy_write enabled by default

session.lazy_write = 0

Detection: Can cause out-of-band session read timing issues

Invalid octal literals now produce a parse error

echo 05678; // PHP 5.x outputs 375

Parse error: Invalid numeric literal in file.php on line 2

Detecting parse errors is easy: php -l

Static Analysis

github.com/etsy/phan

% phan -h
Usage: ./phan [options] [files...]
 -f, --file-list <filename>
  A file containing a list of PHP files to be analyzed

 -r, --file-list-only
  A file containing a list of PHP files to be analyzed to the
  exclusion of any other directories or files passed in. This
  is useful when running Phan from a stored state file and
  passing in a small subset of files to be re-analyzed.

 -l, --directory <directory>
  A directory to recursively read PHP files from to analyze

 -3, --exclude-directory-list <dir_list>
  A comma-separated list of directories for which any files
  included from that directory will not be analysis. Note
  that adding a directory here will not cause its files to
  be parsed.

 -d, --project-root-directory
  Hunt for a directory named .phan in the current or parent
  directory and read configuration file config.php from that
  path.

 -m <mode>, --output-mode
  Output mode from 'text', 'json', 'codeclimate', or 'checkstyle'

 -o, --output <filename>
  Output filename

 -p, --progress-bar
  Show progress bar

 -a, --dump-ast
  Emit an AST for each file rather than analyze

 -e, --expand-file-list
  Expand the list of files passed in to include any files
  that depend on elements defined in those files. This is
  useful when running Phan from a state file and passing in
  just the set of changed files.

 -q, --quick
  Quick mode - doesn't recurse into all function calls

 -b, --backward-compatibility-checks
  Check for potential PHP 5 -> PHP 7 BC issues

 -i, --ignore-undeclared
  Ignore undeclared functions and classes

 -y, --minimum-severity <level in {0,5,10}>
  Minimum severity level (low=0, normal=5, critical=10) to report.
  Defaults to 0.

 -c, --parent-constructor-required
  Comma-separated list of classes that require
  parent::__construct() to be called

 -x, --dead-code-detection
  Emit issues for classes, methods, functions, constants and
  properties that are probably never referenced and can
  possibly be removed.

 -j, --processes <int>
  The number of parallel processes to run during the analysis
  phase. Defaults to 1.

 -z, --signature-compatibility
  Analyze signatures for methods that are overrides to ensure
  compatiiblity with what they're overriding.

 -h,--help
  This help information

% phan -i -b display.php

display.php:416 CompatError expression may not be PHP 7 compatible

echo preg_replace('/:-:(.*?):-:/e', '$this->pres->\\1', $text);

echo preg_replace_callback(
    '/:-:(.*?):-:/', 
    function($matches) {
      return $this->pres->$matches[1]; // Oops!
    },
    $text);

echo preg_replace_callback(
    '/:-:(.*?):-:/', 
    function($matches) {
      return $this->pres->{$matches[1]}; // Ok
    },
    $text);

% git clone https://github.com/Seldaek/monolog.git
% cd monolog
% find . -name '*.php' | grep -v test > filelist.txt
% phan -i -f filelist.txt

./src/Monolog/Handler/ChromePHPHandler.php:178 PhanTypeMismatchReturn Returning type int but headersAccepted() is declared to return bool
./src/Monolog/Handler/ElasticSearchHandler.php:124 PhanTypeMismatchArgumentInternal Argument 3 (previous) is \elastica\exception\exceptioninterface but \runtimeexception::__construct() takes \runtimeexception|\throwable
./src/Monolog/Handler/FirePHPHandler.php:81 PhanTypeMismatchReturn Returning type array but createRecordHeader() is declared to return string
./src/Monolog/Handler/FirePHPHandler.php:153 PhanTypeMismatchArgumentInternal Argument 1 (array_arg) is string but \current() takes array
./src/Monolog/Handler/FirePHPHandler.php:154 PhanTypeMismatchArgumentInternal Argument 1 (array_arg) is string but \current() takes array
./src/Monolog/Handler/FirePHPHandler.php:154 PhanTypeMismatchArgumentInternal Argument 1 (array_arg) is string but \key() takes array
./src/Monolog/Handler/FlowdockHandler.php:70 PhanTypeMissingReturn Method \monolog\handler\flowdockhandler::getdefaultformatter is declared to return \monolog\formatter\formatterinterface but has no return value
./src/Monolog/Handler/GelfHandler.php:55 PhanTypeMismatchProperty Assigning null to property but \monolog\handler\gelfhandler::publisher is \gelf\imessagepublisher|\gelf\publisher|\gelf\publisherinterface
./src/Monolog/Handler/MandrillHandler.php:49 PhanSignatureMismatch Declaration of function send($content, array $records) should be compatible with function send(string $content, array $records) defined in ./src/Monolog/Handler/MailHandler.php:46
./src/Monolog/Handler/NativeMailerHandler.php:117 PhanSignatureMismatch Declaration of function send($content, array $records) should be compatible with function send(string $content, array $records) defined in ./src/Monolog/Handler/MailHandler.php:46
./src/Monolog/Handler/RedisHandler.php:41 PhanTypeMismatchDefault Default value for int $capSize can't be bool
./src/Monolog/Handler/SocketHandler.php:115 PhanTypeMismatchProperty Assigning float to property but \monolog\handler\sockethandler::timeout is int
./src/Monolog/Handler/SocketHandler.php:126 PhanTypeMismatchProperty Assigning float to property but \monolog\handler\sockethandler::writingTimeout is int
./src/Monolog/Handler/SocketHandler.php:218 PhanTypeMismatchArgumentInternal Argument 2 (seconds) is float but \stream_set_timeout() takes int
./src/Monolog/Handler/SocketHandler.php:218 PhanTypeMismatchArgumentInternal Argument 3 (microseconds) is float but \stream_set_timeout() takes int
./src/Monolog/Handler/SocketHandler.php:274 PhanTypeMismatchProperty Assigning resource to property but \monolog\handler\sockethandler::resource is null
./src/Monolog/Handler/StreamHandler.php:65 PhanTypeMismatchProperty Assigning null to property but \monolog\handler\streamhandler::stream is resource|string
./src/Monolog/Handler/StreamHandler.php:86 PhanTypeMismatchProperty Assigning null to property but \monolog\handler\streamhandler::stream is resource|string
./src/Monolog/Handler/StreamHandler.php:105 PhanTypeMismatchProperty Assigning array|string to property but \monolog\handler\streamhandler::errorMessage is null
./src/Monolog/Handler/SwiftMailerHandler.php:43 PhanSignatureMismatch Declaration of function send($content, array $records) should be compatible with function send(string $content, array $records) defined in ./src/Monolog/Handler/MailHandler.php:46
./src/Monolog/Handler/SyslogUdp/UdpSocket.php:38 PhanTypeMismatchProperty Assigning null to property but \monolog\handler\syslogudp\udpsocket::socket is resource

ChromePHPHandler.php:178 PhanTypeMismatchReturn Returning type int but headersAccepted() is declared to return bool

/**
 * Verifies if the headers are accepted by the current user agent
 *
 * @return Boolean
 */
protected function headersAccepted() {
    if (empty($_SERVER['HTTP_USER_AGENT'])) {
        return false;
    }
    return preg_match('{\bChrome/\d+[\.\d+]*\b}', $_SERVER['HTTP_USER_AGENT']);
}

FirePHPHandler.php:154 PhanTypeMismatchArgumentInternal Argument 1 (array_arg) is string but \current() takes array

/**
 * Base header creation function used by init headers & record headers
 *
 * @param  array  $meta    Wildfire Plugin, Protocol & Structure Indexes
 * @param  string $message Log message
 * @return array  Complete header string ready for the client as key and message as value
 */
protected function createHeader(array $meta, $message) {
    $header = sprintf('%s-%s', self::HEADER_PREFIX, join('-', $meta));

    return array($header => $message);
}

/**
 * Creates message header from record
 *
 * @see createHeader()
 * @param  array  $record
 * @return string
 */
protected function createRecordHeader(array $record)
{
    // Wildfire is extensible to support multiple protocols & plugins in a single request,
    // but we're not taking advantage of that (yet), so we're using "1" for simplicity's sake.
    return $this->createHeader(
        array(1, 1, 1, self::$messageIndex++),
        $record['formatted']
    );
}

/**
 * Creates & sends header for a record, ensuring init headers have been sent prior
 *
 * @see sendHeader()
 * @see sendInitHeaders()
 * @param array $record
 */
protected function write(array $record)
{
    if (!self::$sendHeaders) {
        return;
    }

    // WildFire-specific headers must be sent prior to any messages
    if (!self::$initialized) {
        self::$initialized = true;

        self::$sendHeaders = $this->headersAccepted();
        if (!self::$sendHeaders) {
            return;
        }

        foreach ($this->getInitHeaders() as $header => $content) {
            $this->sendHeader($header, $content);
        }
    }

    $header = $this->createRecordHeader($record);
    if (trim(current($header)) !== '') {
        $this->sendHeader(key($header), current($header));
    }
}

PHP 7 Tuning

Check your phpinfo()

Opcache

opcache.memory_consumption=2048
opcache.max_accelerated_files=100000
opcache.validate_timestamps=1
opcache.revalidate_freq=2
opcache.save_comments=0
opcache.enable_file_override=0
opcache.enable_cli=0
opcache.max_wasted_percentage=10
opcache.interned_strings_buffer=128
opcache.fast_shutdown=1
opcache.huge_code_pages=1

Opcache

Huge Pages

$ sysctl -w vm.nr_hugepages=512
vm.nr_hugepages = 512
(Add it to your /etc/sysctl.conf)

$ grep Huge /proc/meminfo
AnonHugePages:      6144 kB
HugePages_Total:     512
HugePages_Free:      300
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB

USE_ZEND_ALLOC_HUGE_PAGES=1 httpd ...

increase realpath_cache_size

realpath_cache_size=128k

If using MySQL, use mysqlnd

Check your command buffer usage

DocumentRoot on tmpfs

$ mount | grep tmpfs
tmpfs on /var/www type tmpfs (rw,relatime,size=12288000k,mode=755)

$ ls -la /var/www
total 5
drwxr-xr-x  5 root   root    160 Feb 23 02:47 .
drwxr-xr-x 26 root   root   4096 Feb  7 19:40 ..
lrwxrwxrwx  1 root   root     14 Feb 23 02:47 current -> /var/www/A
drwxrwxr-x 25 apache apache  640 Feb 11 22:04 A
drwxrwxr-x 25 apache apache  640 Feb 11 22:04 B

Application-level changes?

Remember this?

$a = [];
for($i=0; $i < 100000;$i++) {
    $a[] = ['abc','def','ghi','jkl','mno','pqr'];
}
echo memory_get_usage(true);

// PHP 5.x  109M
// PHP 7.0   42M no opcache
// PHP 7.0    6M with opcache enabled

Use it!

include 'config.php'; // $config = [ ... ]

include 'countries.php'; // $countries = [ 'CA'=>'Canada', ... ]

Hyperthreading and NUMA

HyperThreading handles extreme loads better
If you don't have multi-socket servers, turn on HT and move on
For multi-socket servers, things get interesting

Digital Ocean

$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                2
On-line CPU(s) list:   0,1
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             2
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 63
Model name:            Intel(R) Xeon(R) CPU E5-2650L v3 @ 1.80GHz
Stepping:              2
CPU MHz:               1797.917
BogoMIPS:              3595.83
Virtualization:        VT-x
Hypervisor vendor:     KVM
Virtualization type:   full
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              30720K
NUMA node0 CPU(s):     0,1

Multi-socket bare metal without HT

$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                24
On-line CPU(s) list:   0-23
Thread(s) per core:    1
Core(s) per socket:    12
Socket(s):             2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 63
Model name:            Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz
Stepping:              2
CPU MHz:               1203.320
BogoMIPS:              5005.24
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              30720K
NUMA node0 CPU(s):     0-11
NUMA node1 CPU(s):     12-23

Multi-socket bare metal with HT

$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                48
On-line CPU(s) list:   0-47
Thread(s) per core:    2
Core(s) per socket:    12
Socket(s):             2
NUMA node(s):          2
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 63
Model name:            Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz
Stepping:              2
CPU MHz:               1200.000
BogoMIPS:              5004.73
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              30720K
NUMA node0 CPU(s):     0-11,24-35
NUMA node1 CPU(s):     12-23,36-47

Solutions?

numactl --interleave=all httpd/php-fpm
split multi-socket with containers
BIOS Snoop Mode setting? HS/ES/COD?
ignore it

Let's deploy it!

Atomic

No performance hit

No restarts
No LB removal
No thundering herd
Cache reuse

Must be able to serve two versions of the site concurrently!

Requests that begin on DocumentRoot A must finish on A

Set the DocumentRoot to symlink target!

Easy with nginx

fastcgi_param DOCUMENT_ROOT $realpath_root

Apache

github.com/etsy/mod_realdoc

Avoid hardcoding full paths

Watch your include_path setting

incpath extension can resolve your include_path for you

https://github.com/etsy/incpath

Version all static assets

DB Schema changes need special care

PHP 7 in production

Thank You

https://github.com/rlerdorf/php7dev

https://github.com/rlerdorf/phan

https://bugs.php.net

http://talks.php.net/unam

Report Bugs

Useful bug reports, please!