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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Parallel processing in PHP

PHP is designed - where necessary to the exclusion of other uses - as a web page tool. In other words, where a language design decision needs to made between something that is good for the web use, but bad for more general use, the decision will always be in favour of the web. "I don't care how it effects the other users" said Rasmus Lerdorf when I attended a lecture of his a year or two back - but what Rasmus (the PHP originator and mentor) means is that he really does care that it should be great for web users.

So ... most of the other language I teach had a "fork" function or equivalent from the early days which lets you split the process in two, with each half performing a different task. In PHP, it's there too - as from 4.1 - under the name pcntl_fork. But forking a complete process can be resource-heavy and tricky to code and there are other options too - such as setting off parallel actions on pipes.

Here's some sample code links.

Pinging multiple hosts in parallel
Grabbing titles from multiple pages in parallel
You can try the second example here if you wish.

You'll notice that I've used the full path to PHP and my test script in the title grabber. That's because the PHP script will be called up with goodness only knows what path and current directory, and it's sometimes needed to get the thing to work. You may also find that some of the php.ini settings hamper you.

Finally, a note of caution. If you write a script that goes out and grabs lots of information from other servers, you're writing an automata or robotic process and you should check that this is acceptable to your target site - their robots.txt file.
(written 2007-01-03)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
W603 - Web and Intranet - Server Side Technologies
  [642] How similar are two words - (2006-03-11)
  [653] Easy feed! - (2006-03-21)
  [732] Where is a web site visitor browsing from - (2006-05-24)
  [1031] robots.txt - a clue to hidden pages? - (2007-01-13)
  [1355] .php or .html extension? Morally Static Pages - (2007-09-17)
  [1365] Korn Shell scripts on the web - (2007-09-25)
  [1554] Online hotel reservations - Melksham, Wiltshire (near Bath) - (2008-02-24)
  [1615] PHP training courses every month - (2008-04-18)
  [1749] Using server side and client side programming together - (2008-08-11)
  [2055] Effect on server when memory runs out and swapping starts - (2009-02-26)
  [2282] Checking robots.txt from Python - (2009-07-12)
  [3705] Django Training Courses - UK - (2012-04-23)
  [3915] How does PHP work? - (2012-11-07)
  [4277] Sending a message to the server and changing text on a page when a button is pressed - (2014-05-23)

H999 - Additional PHP Material
  [54] PHP and natural sorting - (2004-09-19)
  [239] What and why for the epoch - (2005-03-08)
  [320] Ordnance Survey - using a 'Get a map' - (2005-05-22)
  [322] More maps - (2005-05-23)
  [337] the array returned by preg_match_all - (2005-06-06)
  [372] Time calculation in PHP - (2005-07-08)
  [468] Stand alone PHP programs - (2005-10-18)
  [483] Double Dollars in PHP - (2005-11-02)
  [493] Running a Perl script within a PHP page - (2005-11-12)
  [563] Merging pictures using PHP and GD - (2006-01-13)
  [603] PHP - setting sort order with an associative array - (2006-02-13)
  [665] PHP Image viewing application - (2006-04-01)
  [687] Presentation, Business and Persistence layers in Perl and PHP - (2006-04-17)
  [789] Hot answers in PHP - (2006-07-02)
  [806] Check your user is human. Have him retype a word in a graphic - (2006-07-17)
  [822] PHP - a team member leaves - (2006-08-04)
  [839] Reporting on the 10 largest files or 10 top scores - (2006-08-20)
  [917] Syntax checking in PHP - (2006-11-07)
  [937] Display an image from a MySQL database in a web page via PHP - (2006-11-22)
  [1010] Dates, times, clickable diarys in PHP - (2006-12-28)
  [1053] Sorting people by name in PHP - (2007-01-26)
  [1104] Drawing dynamic graphs in PHP - (2007-03-09)
  [1194] Drawing hands on a clock face - PHP - (2007-05-19)
  [1270] PHP Standalone - keyboard to screen - (2007-07-18)
  [1389] Controlling and labelling Google maps via PHP - (2007-10-13)
  [1390] Converting from postal address to latitude / longitude - (2007-10-13)
  [1391] Ordnance Survey Grid Reference to Latitude / Longitude - (2007-10-14)
  [1451] More PHP sample and demonstration programs - (2007-12-01)
  [1485] Copyright and theft of images, bandwidth and members. - (2007-12-26)
  [1505] Script to present commonly used images - PHP - (2008-01-13)
  [1519] Flipping images on your web page - (2008-01-26)
  [1623] PHP Techniques - a workshop - (2008-04-26)
  [2073] Extra PHP Examples - (2009-03-09)
  [2215] If nothing, make it nothing. - (2009-06-02)
  [2684] Exception handling in PHP - (2010-03-18)
  [3118] Arrays of arrays - or 2D arrays. How to program tables. - (2011-01-02)
  [3210] Catchable fatal error in PHP ... How to catch, and alternative solutions such as JSON - (2011-03-22)
  [4655] Image indexer / thumbnail display scripts in PHP - (2016-02-25)

H308 - PHP - Searches, and search engines
  [1735] Finding words and work boundaries (MySQL, Perl, PHP) - (2008-08-03)
  [2137] Reaching the right people with your web site - (2009-04-23)
  [2166] Crossrefering documents with uniqueness and inconsistency issues - PHP proof of concept demo - (2009-05-10)
  [2631] How to show a large result set page by page in PHP - (2010-02-11)
  [3159] Returning multiple values from a function call in various languages - a comparison - (2011-02-06)
  [3163] Twitter - the special use of @ # and http: in tweets - (2011-02-09)
  [4401] Selecting RECENT and POPULAR news and trends for your web site users - (2015-01-19)


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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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