HipHop for PHP is a source code transformer for PHP script code. Hiphop for PHP is a set of PHP execution engines. HipHop started as project at Facebook Inc. and was later made open source. Till date, facebook has achieved 6X reduction in CPU utilization for its site using HipHop as compared to Apache.
One of the design of HipHop was to write complex logic with PHP. Since PHP is an interpreted language, it is bound to be slow. Companies like Facebook which have large PHP codebases would have to write their complex functionality with extensions in C or C++. This would lead to lesser amount of resources which could work on the complete codebase. By continuing to use PHP with HipHop Facebook is able to maintain a high number of engineers who can work on the whole codebase.
HipHop has evolved over the years. Initially it started as 'HPHPc' which translates the PHP code to C++ code and then passes it to gcc which compiles it into one monolithic binary representing the site's entire code tree. This gave significant performance gains, but it was horrible for development. The most important reason to use PHP is to avoid having to recompile for every small change, since PHP is a interpreted language.
'HPHPi' came hereafter as an interactive version of HPHP. It had the feature to automatically recompile on changing the behavior, but it led to different behavior in development and production machine which is risky.
HipHop Virtual Machine (HHVM)was created with an intent to replace both HPHPc and HPHPi. HHVM does not call gcc unlike its predecessors. HHVM transforms PHP code to byte code just as regular PHP does. It differs from the regular PHP due to its optimizer and JIT(Just in Time Compilation).
The following article gives a complete picture of HipHop VM :
https://www.facebook.com/note.php?note_id=10150415177928920
One of the design of HipHop was to write complex logic with PHP. Since PHP is an interpreted language, it is bound to be slow. Companies like Facebook which have large PHP codebases would have to write their complex functionality with extensions in C or C++. This would lead to lesser amount of resources which could work on the complete codebase. By continuing to use PHP with HipHop Facebook is able to maintain a high number of engineers who can work on the whole codebase.
HipHop has evolved over the years. Initially it started as 'HPHPc' which translates the PHP code to C++ code and then passes it to gcc which compiles it into one monolithic binary representing the site's entire code tree. This gave significant performance gains, but it was horrible for development. The most important reason to use PHP is to avoid having to recompile for every small change, since PHP is a interpreted language.
'HPHPi' came hereafter as an interactive version of HPHP. It had the feature to automatically recompile on changing the behavior, but it led to different behavior in development and production machine which is risky.
HipHop Virtual Machine (HHVM)was created with an intent to replace both HPHPc and HPHPi. HHVM does not call gcc unlike its predecessors. HHVM transforms PHP code to byte code just as regular PHP does. It differs from the regular PHP due to its optimizer and JIT(Just in Time Compilation).
The following article gives a complete picture of HipHop VM :
https://www.facebook.com/note.php?note_id=10150415177928920
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