Web Performance First Aid. Alan Seiden Consulting alanseiden.com

Transcription

1 alanseiden.com

2 My focus Advancing PHP on IBM i PHP project leader, Zend/IBM Toolkit Contributor, Zend Framework DB2/i enhancements Developer, Best Web Solution, IBM/Common Authority, subsecond web performance on IBM i/iseries 2

3 Contact information Alan Seiden alanseiden.com 3

4 Where to download these slides From my site On SlideShare The latest version will be available on both sites 4

5 What we ll discuss today Why web performance matters Performance big picture Tools that show issues visually Tips and configurations Several PHP speed tips Q&A 5

6 Why performance matters 6

7 Speed = money Google s experiment Google Search lists 10 results per page They tested pages of 30 results Traffic and revenue dropped by 20% Why? 10 results took.4 seconds to generate 30 results took.9 seconds A ½ second delay caused a 20% drop in traffic Source: marissa-mayer-at-web-20.html 7

8 Speed = competitiveness Search engine ranking Since early 2010, Google s search algorithm has included speed Faster sites rank higher, all else being equal Consumers lose patience with slow sites With many choices, users give up on sites that drag Patience has decreased since the 1990s Slower sites often waste bandwidth and CPU Costly infrastructure driven by performance mistakes 8

9 User experience affected by speed If slow enough, site appears broken Site may time out with error message User not sure if site is up Too long a wait: user loses train of thought Speed inspires confidence 9

10 This talk can get you started Based on my own consulting experience I ve been brought in when poor web performance is about to terminate a project Important: a calm, objective, confident attitude Restoring confidence is enjoyable Watch the response times steadily improve Most dramatic: home page went from 101 seconds to subsecond Additional motivation for me: proving that the client made a good decision to run site on IBM i 10

11 Understanding HTTP (web) flow 11

12 Request-response protocol Client (browser) requests a file; server responds One file at a time (at most 2 6 in parallel) Browser requests HTML file, then as it parses HTML, finds other file names to request (images, css, js...) 12

13 Each request passes through several layers 13

14 You might guess one top strategy Each HTTP request travels through several layers A common-sense performance strategy suggests itself Reduce the number and size of HTTP requests 14

15 Tools 15

16 Performance tools help in many ways Visualize HTTP requests Find ways to eliminate requests or shrink responses Test more easily Capture before and after results For your own documentation For a report to management 16

17 Favorite performance browser tools Web Developer Toolbar Live HTTP Headers Firebug FirePHP Page Speed from Google

18 Web Developer Toolbar Web Developer Toolbar Favorite peformance testing trick: Disable cache to test first time in performance 18

19 Live HTTP Headers Live HTTP Headers Shows the flow of HTTP request/response Example: Capture the URL launched before redirect 19

20 Firebug Firebug Along with FirePHP (PHP only) and Page Speed, empowers anyone for performance 20

21 Firebug Net tab example 21

22 Page Speed Page Speed from Google Analyzes your site, suggests performance techniques 22

23 Use compression 23

24 Compression reduces file size Called gzip or mod_deflate, the same for our purposes Compresses, speeds up html, javascript, css, favicons, anything text-based 24

25 Netflix saw improvement with gzip/ deflate Saw 13-25% performance improvement Cut outbound traffic in half That saves money for a busy site such as Netflix Details: It really works! 25

26 Details of deflate/gzip compression Apache directives (sample) # Load IBM i's module that performs compression LoadModule deflate_module /QSYS.LIB/QHTTPSVR.LIB/QZSRCORE.SRVPGM # Specify content types to compress AddOutputFilterByType DEFLATE application/x-httpd-php application/ json text/css application/x-javascript application/javascript text/html Tutorial on my blog: Apache reference: 26

27 Reduce HTTP requests 27

28 HTTP requests are costly Each request makes a round trip to server and back Each HTTP request consumes bandwidth and CPU In-network tests do not measure end-user performance outside the network Users could have unpredictable DSL or mobile connections Firewalls and proxy servers may sit between the web server and end user I ve seen some convoluted network configurations 28

29 Requests cause blocking in browser Browsers typically limit themselves to 2 parallel requests to a given server File requests stack up, blocked by prev. requests Above, even not modified files caused blocking Solution: reduce number of images or improve caching via Expires headers 29

30 More ways to reduce blocking If many.js or.css files are used: Combine them into fewer files Move contents of smaller.js or.css files inline to your pages, eliminating those external files Page Speed tool will help you decide 30

31 Create a favicon for your site Browsers always look for a file called favicon.ico in your document root Those little icons that appear in the browser Once found, will be remembered by browser If not found, will be requested every time How to create a favicon: 31

32 Keep-alive 32

33 Keep HTTP connections alive Keep-alive setting in Apache (or any web server) The HTTP job will stay open, waiting for you Good when downloading many images, css, js files Configurable by number of seconds to keep connection open, number of files to be downloaded KeepAlive On KeepAliveTimeout 15 (Details: core.html#keepalive) Don t overdo it you are locking out other users from that HTTP job while it s dedicated to you 33

34 Connecting takes time Clues that Keepalive is off Connection: close, Connecting Example bottom right: 3.6 seconds Connecting (longer than average but it really happened) 34

35 What you see when Keep-alive is on Firebug s Net tab shows Connection: Keep- Alive, and, here, timeout=300 seconds (5 minutes) Zero seconds to connect Keep-alive is working! 35

36 Ajax: friend or foe? 36

37 AJAX=Asynchronous Javascript And XML AJAX updates parts of a page without reloading the whole page Not always XML. These days, JSON too Requests and file sizes are generally small Meant to bring SPEED to the web Potential problems if overused 37

38 AJAX mistake #1 Too much of a good thing Requiring several AJAX requests to complete before the page itself can load fully Too many HTTP requests at once I ve seen a situation where 4 AJAX requests were embedded in a page load The AJAX doesn t even start till the page loads Causes blocking as the requests pile up, waiting for the previous ones to complete Solution: when page first loads, embed AJAX content in the page Re-use logic on the server side when building page Subsequent updates can be done with AJAX 38

39 AJAX mistake #2 Duplicate requests Might go unnoticed with javascript library tools (Dojo, jquery...) Happens more than you would expect! Common, actually 39

40 AJAX mistake #3 Dynamically generating static content (don t do that) Solutions: Change to static files Cache URLs (e.g. with Zend Data Cache if using PHP, or Apache caching) See example below, before and after caching (Apologies for blurring: protecting confidentiality) 40

41 Persistent db connections 41

42 Persistence = connection pool On IBM i, job initialization is relatively slow Gives us good things auditing, logging, security Solution: a pool of pre-initialized jobs Pre-started DB2 jobs save time Generally run in subsystem QSYSWRK, job name QSQSRVR These prestart jobs can be configured with CHGPJE command In PHP, persistent connections reuse initialized jobs db2_pconnect() Dramatic speed boost 42

43 Use db2_pconnect() resource db2_pconnect ( string $database, string $username, string $password [, array $options ] ) Persistent is much faster than non-persistent db2_pconnect can reuse connections, reducing the time needed to connect (after the first time) to almost zero How db2_pconnect() reuses connections Connections defined by database, username, and password Tries to reuse an existing connection matching these 3 params May create new connection, anyway, if heavy system load db2_close() on a persistent connection does nothing db2_pclose() forces the conn to close 43

44 db2_pconnect() example with library list $database = 'MYDB'; $user = 'MYUSER'; $password = 'MYPASS'; // set library list (works the same for connect or pconnect) $options = array('i5_naming' => DB2_I5_NAMING_ON, 'i5_libl' => 'MYLIB1 MYLIB2' ); $conn = db2_pconnect($database, $user, $password, $options); if ($conn) { echo "Connection succeeded."; } else { echo "Connection failed."; } // MYTABLE will be found, if in library MYLIB1 or MYLIB2 $stmt=db2_exec($conn,"select * FROM MYTABLE"); 44

45 Rules for using persistence Because connections are shared when defined with an identical database, user, and password, please: Avoid unpredictable results by also specifying the same $options for these connections Promote sharing of jobs by minimizing the number of user profiles that you connect with Each user profile creates a new set of database jobs Each set of jobs consumes system resources More information: DB2 and PHP Best Practices on IBM i at presentations 45

46 Reduce IFS reads/ writes 46

47 IFS is a weak performer on IBM i IBM i reverses the normal dynamic Database (DB2) is fast; stream file access (IFS) is slow Slow is a relative term. Depends on system and how many files accessed Not as important as reducing HTTP access or other network activity, for example Here are several tips... 47

48 Tips to reduce IFS accesses Turn off or reduce logging to files in production Large log files can be a culprit on some systems Make files cacheable for long periods of time by setting expires headers If using a scripting language such as PHP, use an opcode cache (see Optimizer+ discussion later in presentation) In the UNIX world, stream file access is called stat. Any tips for reducing stats will be effective on IBM i Example: in Apache, turn off checking for.htaccess files if you re not using them, with AllowOverride none # disable htaccess checks <Directory /> AllowOverride none </Directory> 48

49 System specs, work management 49

50 System specs Memory and CPU speed will make a difference Power 7 machines help IBM i v7.1 speeds up complex DB2 queries If you think your machine may be underpowered, ask a professional to evaluate (see next slide) I ve seen some underpowered machines, sometimes not enough memory for their interactive workload, even before adding a web workload 50

51 Work management Memory pools, routing A presentation by Jim Oberholtzer (atallc.net), PHP and the Systems Administrator, addresses work management Jim suggests adding a second memory pool for subsystems QHTTPSVR and ZENDSVR See his presentation for details 51

52 PHP-specific speed tips 52

53 Zend Server for IBM i Download Click on the IBM i tab Two versions Zend Server Community Edition (CE): no charge regular Zend Server (extra features) has a charge The download is the same; license is different More about this on next slide 53

54 Ensure you have a Zend Server license Full trial license comes with download After license expires, you can still use basic CE features But without a valid license, you experience a performance penalty Zend Server looks for a license that isn t there See next slide for solution... 54

55 Get a license: either premium or CE Even the no-charge license will protect you from performance degradation One customer told me adding a license gave his site a big speed boost Request CE license here: You ll need your IBM i serial number (DSPSYSVAL QSRLNBR) Enter the license in Zend Server license page 55

56 Make the most of Optimizer+ Optimizer+: opcode cache that speeds PHP execution The first time a PHP script runs, Optimizer+ stores the compiled version in memory, speeding future runs Works well with its default settings What s configurable? Amount of memory to allocate to Optimizer+ Number of scripts to keep in memory Timestamp-checking interval How often to check if a script has been changed Next slide: details on the timestamp-checking interval 56

57 Timestamp checking by Optimizer+ Timestamp validation frequency: how often Optimizer+ will check if a script has been changed Ensures you are not running stale code Default: 2 seconds The default (2 secs) is usually OK For max speed, disable timestamp validation Use in production only Usually only a small improvement But I ve seen BIG improvement on systems with slow IFS access Caution if you turn off timestamp validation: Changes to your app NOT applied till you clear optimizer cache Good reason to keep timestamp validation on in development env. 57

58 How to turn off timestamp validation From Zend Server GUI Server Setup->Optimizer+ Directives Zend_optimizerplus.validate_timestamps = Off ; Restart PHP 58

59 Turn off unused PHP extensions Extensions provide extra functionality to PHP Each one uses memory Many are enabled by default Turn off those that you do not use Do not turn off extensions needed by Zend Server s GUI See my blog for exact instructions 59

60 Premium features that can help Zend Monitor and Code Trace identify bottlenecks Particularly helpful when app is built on a framework Zend Job Queue offloads long-running processes to run asynchronously Example: sending an message or crunching large datasets Details: PHP Batch Jobs on IBM i from presentations 60

61 New open source PHP IBM i toolkit Ships with Zend Server 5.6+ Look for PTFs and hotfixes on download page Many improvements since first release Young i Professionals site Zend Forum PHP on IBM i -> Zend Server for IBM i -> New Toolkit Many tips there How to share DB2 connection with toolkit: Persistent connection is the fastest 61

62 Resources, Q&A 62

63 Resources My webinar w/ Mike Pavlak, Performance Tuning PHP on IBM i Yahoo! s rules for good performance Performance Calendar Meetup groups: live and remote Steve Souders (formerly Yahoo!, now Google) Books: High Performance Web Sites, Even Faster Web Sites 63

64 Q&A Share your experiences What performance situations have you faced? Are you handling any web performance problems now? 64

65 Alan s upcoming appearances Oct. 17 Webcast ipro Developer Online Conference Oct ZendCon Santa Clara, Calif. Dec. 11 Webcast Zend: ZF2 for IBM i 65

66 Contact Get tips Alan Seiden Ho-Ho-Kus, NJ alanseiden.com Free tips newsletter: alanseiden.com/tips