apache written in c versus c++

Mark Rowe Fri, 12 Mar 2004 10:39:01 -0800

c is smaller than c++ STL,

Using apache 2.0.48

I defined my own string struct
and my own 'mystrcat' function
and tenbyte_string as "0123456789"
which is ten bytes.

Did this iteration 30,000 times as shown
below.  It ran fast and small.
It built a string with a strlen() of 300,000
The child never grew beyond about 300 KB
of the resting child process.  All children
dropped back down below 2 MB when
they were done.

I hammered it!  I held down the 'F5' key on
this page on a high bandwidth connection
for 2 minutes or more.

Apache was fine very fast spawned many
children.  All children were small and returned
to below 2 MB when I let up on 'F5' key.

---------------------------------------------------------------------------------------------------------------
#define tenbyte_string "0123456789"


typedef struct mystr {
        char *p;
        int len;
} String;


void mystrcat(String *s, char *str) {
        char *tmp_str = s->p;
        int str_len = strlen(str);
        s->p = realloc(tmp_str, s->len + str_len + 1 );
        strcpy(s->p + s->len, str);
        s->len += str_len;
}


void fun(void) {
        fprintf(stderr, "cannot create pool\n");
}

static int x_handler(request_rec *r)
{
        int i;
        String s = {0};

    if (strcmp(r->handler, "example-handler")) {
        return DECLINED;
    }

ap_set_content_type(r, "text/html");

    if (r->header_only) {
        return OK;
    }

ap_rputs(DOCTYPE_HTML_3_2, r); ap_rputs("<HTML>\n", r); ap_rputs(" <HEAD>\n", r); ap_rputs(" <TITLE>mod_example Module Content-Handler Output\n", r); ap_rputs(" </TITLE>\n", r); ap_rputs(" </HEAD>\n", r); ap_rputs(" <BODY>\n", r); ap_rputs(" <H1><SAMP>mod_example</SAMP> Module Content-Handler Output\n", r); ap_rputs(" </H1>\n", r); ap_rputs(" <P>\n", r); ap_rprintf(r, " Apache HTTP Server version: \"%s\"\n", ap_get_server_version()); ap_rputs(" <BR>\n", r); ap_rprintf(r, " Server built: \"%s\"\n", ap_get_server_built()); ap_rputs("<h1>hello 30,000 world</h1><br>\n", r);

        for (i = 0; i < 30000; i++) {
                mystrcat(&s, tenbyte_string);
        }

        ap_rprintf(r, "strlen(s.p)=%d\n", strlen(s2.p));
        free(s.p);


    ap_rputs(" </BODY>\n", r);
    ap_rputs("</HTML>\n", r);

    return OK;
}

---------------------------------------------------------------------------------------------------------------


Then I put the above code in to a single
command line program set iterations to
1,000,000 to make a 10,000,000 byte
long string.  The program took 1.33 seconds
and it took 10,002,432 max mmap bytes
according to malloc_stats();

        int i = 0;
        String s2 = {0};

        for (i = 0; i < 1e6; ++i) {
                mystrcat(&s2, tenbyte_string);
        }


Then I wrote the same equivalent code
in c++ using STL it took 1.25 seconds
and it took 25,174,016 bytes according
to malloc_stats();

        int i = 0;
        string s = "";

        for(i=0; i < 1e6; ++i) {
                s += tenbyte_string;
        }


So the c program took 1.33/1.25 = 1.06
times longer than the c++ program .

The c++ program took about 2.5 times
as much RAM as the c program.

c++ is marginally faster but takes
over twice as much RAM as c.

So if Apache is written well enough then
it will be very nearly as fast as if written in c++
and run in less than half the size in RAM from
this preliminary study.

My tests were run using gcc version
2.96 running on Redhat version 7.2
on an old Dell PowerApp 110 with
128 MB or RAM, 265 MB swap
and 600 MHz 80526 cpu.
glibc was GNU C Library stable release version 2.2.4

--- Mark R. Rowe, MSEE

apache written in c versus c++

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