CppCMS Blog :: Cache

Version 0.99.9 Released

New Features:

Clang is support provided, CppCMS was tested against Clang 2.8.

Now CppCMS supports 5 families of C++ compilers:
- GCC 3.4.x to 4.6.1
- Visual Studio 2005 - 2010
- Clang 2.8
- Intel 11
- Sun Studio 5.10
Significant performance improvements in XSS filtering by rewriting URI validation using a C++ parser rather then using complex regular expression.

Added support of fully custom validation for HTML attributes using callback functions in the XSS filter.
Significant performance improvements over multiple places in code by eliminating multiple memory allocations:
- HTTP, SCGI and FastCGI backends - improved memory allocation for CGI variables.
- Fetching values from JSON objects using get(...), find(...) APIs is now done with 0 memory allocation.
- URL mapping is now done with 0 or very low memory allocation.
- Various filters like escape, urlencode and some others now work with no or few memory allocations.
Performance improvements in caching by replacing the balanced binary tree by hash table in the primary cache key index.

Breaking Changes:

json::object had changed from std::map<std::string,value> to std::map<string_key,value>. It should be fully transparent for almost all users.

Bugs:

Fixed a crash in http::response when writing HTTP headers throws due for example to incorrect file permissions.
Fixed a bug in booster::regex that prevented some valid patterns to be matched against some regular expressions.
Fixed a bug that may prevent from booster::regex to work on big endian 64 bit platforms
Added initial support of Python3 for templates compiler.
Added a workaround for systems that use python3 by default.

CppCMS benchmarks vs Java, C#, PHP

Long time ago I had posted a benchmarks comparing CppCMS based blog and PHP based one.

I wanted to compare real life applications with each other. For a long time I had been searching for similar applications in several technologies doing very similar jobs in leading technologies: PHP, Asp.Net and Java/JSP. The last two were particularly important as they use static type system and "compiled" languages as C# and Java that are known to be faster then other dynamic typed languages like PHP, Python, Ruby and Perl popular in web development.

Setup

Unfortunately I had failed to find such application, so finally I decided to write something representative and small on my own an application with following requirements:

Uses simple time-out based page caching
Uses MySQL and the database and keeps open connections in pool.
For each request access to database (if page is not cached), fetches the page content and comments for "sample article" in blog.
Converts text to HTML using a markdown filter and displays it on page.

I used following technologies:

CppCMS:

Version: 0.99.3
MySQL Connection: dbixx/libdbi library using libmysqlclient
Markdown library: discount
Connection: internal HTTP server
PHP

Version: 5.2.6
MySQL Connection: internal driver
Markdown library: PHP-Makrdown
Connection: Lighttpd 1.4.19 + FastCGI
Bytecode Cache: XCache
Asp.Net/Mono

Version: 2.6.7
MySQL Connection: Connector/Net
Markdown library: MarkdownSharp
Connection: internal HTTP server XSP (found to be much faster than fastcgi server)
JSP/Tomcat

Version - Tomcat: 6.0.18
Version - Java: Sun Java 1.6.0_12
MySQL Connection: Connector/J
Markdown library: jmd-0.8.1
Caching: oscache 2.4.1
Connection: HTTP

I tested following parameters:

Pages per seconds generation for different cache hit/miss ratio: stating from 0% miss ratio up to 100% miss ratio.
Memory usage

For each test the application was "warmed up" with 100 requests to fill the cache, and then 1000 request with max concurrency of 5 request are done, while certain percent of them is new pages and the other are taken from "warmed up" once.

Notes:

I used the fastest Markdown implementation I had found.

C# implementation is the same one that http://stackoverflow.com uses - it is actually heavily optimized implementation based on older C# implementation

The Java implementation is based on the above C# and the fastest one I had found.

Discount is the fastest C implementation of markdown that I had found.

Results:

Summary

C#, Java and PHP implementation behave very similarly and without significant differences.
The memory usage of Java/Tomcat and Mono/Asp.Net was significantly higher - up one or two orders of magnitude in comparison to CppCMS and PHP
Surprisingly PHP behaves very well, in comparison to "compiled" languages like Java and C#.

Revisiting

After doing some profiling it was clear that C implementation of Markdown was significantly faster then all other implementations. So I decided to create my own mini-markdown that make some basic handing of titles, lists, paragraphs and quotes at one level only. That is very simple syntax but implemented similarly in all 4 languages using same algorithm.

The results were following:

The difference between CppCMS and other implementations was still significant but still much smaller then the difference between real markdown implementation. So the performance difference was less dramatic.

2nd Revision

And in the last revision I decided not to use any text filters by fetch ready HTML formatted content from DB and display it on the web as is.

Such comparison actually profile the most basic stuff:

Caching
SQL Connection
Request/Response handling

And would ignore hundreds lines of code used in any web applications responsible for the actual business logic.

Conclusions

Using C++ with CppCMS provides significant performance gains in developing web applications even in very basic case.
The performance is effected not only by the framework itself but also by many other libraries that are in use. Using highly optimized C and C++ libraries may give significant performance gain in many cases.
Such called "jit-compiled" languages as C# and Java and the frameworks based on the use significant amount of memory and still provide much lower performance then the one that can be achieved using real compiled languages like C++.
It is good to remember that these benchmarks are still quite synthetic ones and in real life the actual performance depend on many factors - but using high quality and high performance libraries available for C++ have significant impact on performance.

Results Data

Markdown
---------
Miss %  CppCMS      Mono        PHP         JSP/Tomcat

0       3200.73     747.164     974.142     821.887
1       2891.2      427.727     724.173     337.736
2       2734.69     300.017     544.162     257.44
5       2285.95     162.686     301.507     130.023
10      1749.14     89.4447     174.724     68.5387
20      1247.86     47.7347     93.7919     25.7081
50      642.769     19.8311     38.979      15.1298
100     356.968     9.77116     20.1892     7.96328

Mini-Markdown
---------
Miss %  CppCMS      Mono        PHP         JSP/Tomcat

0       3103.14     763.222     1152.63     744.72
1       2933.97     728.971     1076.38     765.599
2       2944.42     726.338     1016.42     724.869
5       2804.44     661.613     866.32      822.927
10      2592.99     584.725     705.465     753.218
20      2239.03     471.576     507.021     674.488
50      1625.5      309.443     274.962     374.26
100     1156.09     197.123     159.974     164.515

HTML
-----
Miss %  CppCMS      Mono        PHP         JSP/Tomcat

0       3286.51     849.849     1147.21     808.038
1       3055.53     776.305     1137.35     748.829
2       2991.02     691.502     1122.88     693.439
5       2687.84     693.257     1074.22     756.618
10      2390.12     615.311     1016.27     604.452
20      1886.69     521.467     917.225     668.23
50      1947.93     346.672     669.693     289.656

System and Hardware

OS: Linux, Debian Lenny, 64 bit
Hardware: AMD Athlon XP 3000, 64 bit, 1GB memory

Code

The Code can be downloaded from there. note, to run it you will need to have some libraries installed and configure some hardcoded paths to make it run.

more...

CppCMS 0.0.4 Released

Version 0.0.4 of CppCMS had released.

It includes optimizations required for using it in embedded systems.

Normal Embedded Build:

Caching is completely removed. Small memory footprint is very important for embedded system thus, caching stuff in memory is quite useless.
Zlib compression are removed -- it removes dependency on boost::iostreams, zlib and bzip2 libraries.
Removed mod-prefork.
Removed dynamic templates loading --- this feature requires export of symbols to binary and increases its size in order to make RTTI work. Thus, all templates should be statically compiled into the binary.

Embedded CGI Mode:

FastCGI and SCGI APIs are removed
Mod-thread and mod process are removed including all thread pool facilities
Changes in files based session backend to work properly with CGI mode including garbage collection (sessions that had time-out).

Downloads are avialable from Sf Project Page.

Preparing to Beta 2...

What expected in the next beta version:

Now CppCMS is really ready for serving high load sides, thanks to new distributed cache module based on Boost.Asio.

Several CppCMS processes running on different computers can share same cache distributed over several TCP/IP cache servers.
Staticly typed template system that fully integrated with the framework that allows:
- "Django style" template inheritance.
- Powerful extendsions abilities using C++ code directly.
- Static compilation with generated templates code or loading templates as external shared objects.
- Creates a potential for future "forms/widgets" integration.
Various bugfixes and code cleanup.

Possibly included: form validation and generation modules.

to be Continued...

Caching System: Internals

One of the latest implemented features of CppCMS is a caching system.

Each cached entry is stored using:

Unique key that defines the entry
An actual data
Entry lifetime period.
The set of triggers --- this is a feature that is not available in many cache system like memcached.

For example: main page that displays 5 recent posts may have a key main_page and triggers: post_123, post_124, ... , post_128. More then that, each time, during page build, when you fetch some cached data, like a sidebar or set of options, their sets of triggers are automatically added to the set of triggers of the page you build.

For example, when the page is created and sidebar block is fetched from cache all its triggers are automatically added: if sidebar depends of options, then trigger sidebar and options will be automatically added to triggers of main_page.

Thus, when certain trigger is risen, all pages that depends on it are automatically trashed. This makes a cache system quite powerful and easy to control correct data representation.

The developer is expected to create a rational model of data/triggers that represent the relations between parts of internal data and rise these triggers when committing changes to database.

more...

API Changes and mod-prefork

There have been lot of work in recent weeks in order to make deep internal changes in the framework. Now they include:

Transparent support of 3 web server APIs: fastcgi, cgi and scgi.
Support of new mod prefork that allows safer management of worker processes.
Implementation of a cache that is shared between forked processes.

more...

CppCMS vs WordPress

Setup

I had compared two blog systems: this one and WordPress 2.5 with a patched WP-Cache-2 addon. I used following configuration:

Web Server lighttpd 1.4.13
Interface FastCGI
PHP 5.2
Bytecode cacher: XCache 1.2.1
Database MySQL 5.0
Caching for WP: WP-Cache-2 with an additional performance patch
Hardware: AMD Athlon XP 64bit, 1G RAM
OS: Linux, Debian Etch 64bit.

I prepared two blogs that were filled up with 1000 articles each. Each article had 10 comments, all the articles were organized in 10 categories in each blog.

more...

Patch For WP-Cache-2 plugin

I'm going to run a heavy benchmarks comparing WordPress -- the blog system I know very well, with CppCMS based blog -- the system I had written.

The new caching system that was developed for CppCMS is quite smart, it stores the entry pages twice: original and gzip compressed. On heavy loads, this allows serving pages significantly faster because only thing that should be done is to push html or compressed html page directly from the cache. Otherwise, gzip compression (even fastest) would take lots of resources and reduces a preformace of the system.

When it comes to benchmarks, I had discovered that WP-Cache-2 plugin does the job well, but it caches only html version of the file, thus, even if the page is cached it still must pass a compression by Apache's mod_deflate or by PHP engine itself.

I had patched this plugin and now it stores two versions of same page: an original and compressed. and was able to get 60% performace improvement.

WordPress native plugin: 450 requests per second
WordPress patched plugin: 720 requests per second

So after this patch I can feel that the benchmarks would be proper, because without it this would be incorrect to compare time required for fetching a cache with the time required for compressing entry page.

Links:

N.B.: The full benchmarks coming soon

The Roadmap to The First Beta Version of CppCMS

After quite a long period of development I had decided to get prepared to first public beta release of CppCMS.

The major components of this blog and the framework I want to introduce in first beta are following:

Implementation of Django style templates inheritance, filters (done 70%)
Introduce powerful cache system (done 100%)
Replace SOCI by LibDBI (done 100%)
Improve blog: true markdown, LaTeX equations, categories etc. (done 100%)
Write Documentation (done 20%)
Migrate my Hebrew blog from Word Press to CppCMS (done 100%)

There are lots of work to do, but CppCMS now looks much mature then before.

more...

Next Step - Caching

As we had seen in previous article, the benchmarks had shown an ability of CppCMS to produce about 630 compressed pages per second and an output of about 20Mbit/s. Is this enough?

For most of cases it is... But as we had seen I want to use every cycle of the CPU as smart as I can. Even, if the model I had suggested, was able to show "a prove of concept" there is an important point that was missed: "Why should I create same page so many times?"

Caching

This is the next logical step in the development of high performance web development framework.

First of all we should understand a requirements of the caching system:

Efficiency
Support of "dropping cache on update"
Support of drop the cache by timeout
Work using three models: single process cache, shared cache between processes, shared over the network.
Support of caching on entry page level and single view level as well
Transparent storage of compressed content

Lets describe each one of them:

more...

CppCMS Blog :: Cache

Version 0.99.9 Released

New Features:

Breaking Changes:

Bugs:

CppCMS benchmarks vs Java, C#, PHP

Setup

Notes:

Results:

Summary

Revisiting

2nd Revision

Conclusions

Results Data

System and Hardware

Related:

Code

CppCMS 0.0.4 Released

Preparing to Beta 2...

Caching System: Internals

API Changes and mod-prefork

CppCMS vs WordPress

Setup

Patch For WP-Cache-2 plugin

The Roadmap to The First Beta Version of CppCMS

Next Step - Caching

Caching