FW: Sablotron Performance...

[Lee, William]

Hi there,

 

I'm working with the Sablotron 0.44 performance... and found out that most of the time it is spending on allocating little trunk of memory for small string and for appending small strings...

 

To speed up the performance in this area, I have implement a new string class, which replaced both existing DStr and Str classes. The idea is as follows:

 

Each Str object will now contains a pre-allocated buffer of size 1K (customizable in the source code, but 1K is the optimal so far to avoid stack overflow)... Any string assignment/append with work with this buffer unless it caused an overflow, and in that case, a dynamic allocated buffer will be used. The size of the dynamic allocated buffer is round up to the nearest 4K (again, customizable in the source code), and again, any string concatenation will be done within the same buffer, and will be "reallocated" to a bigger size when a bigger one is need.

 

I have run some performance testing against the release/optimized version, and the result are:
        a small one (xml ~90K and xsl ~80K) which took 1050ms before is now takes only 800ms
        a medium size one (xml ~ 300K and xsl ~80K) improved from 2200ms to 1800 ms

(i.e., the average is around 20% improvement).

 

Since I'm new to this mailing list, could anyone let me know what is the procedure/steps to follows for this kind of changes? Or how can I submit the changes in order to get accepted/approved by the group?

 

Also, I believed the following is a bug in datastr.cpp:

 

int Str::compare(const char* otherChars) const
{
    return (strcmp(operator char*(), otherChars) < 0);
}

 

which I believed it should be:

 

int Str::compare(const char* otherChars) const
{
    return (strcmp(operator char*(), otherChars));
}

 

Thanks in advance for your help.

William Lee

datastr.cpp

datastr.h