[ Home | Articles | Account | People | Projects | FAQ ] Name: Ilya Martynov
Member since: 2003-02-27 11:31:21
Last Login: 2010-02-11 17:07:19
Homepage: http://martynov.org/
MongoDB client library: C vs C++
I've been playing a bit with MongoDB recently. Particularly I've looked into source code for client libraries as I was interested in how hard is to change the client API to support async mode of operation. One thing I noticed is that C version of the client library compared to C++ version is shorter and much easier to read. I cannot shake off the feeling that sometimes C++ feels like a step backwards compared to C.
Running Puppet on big scale
This is a rehash of my comment in slashdot discussion and my comment on Alexey Kovrygin's blog post.STOMP messaging for non-Java programmers on top of Apache ActiveMQ
Recently I was researching available options for messaging between Perl programs. In the past I had quite a lot of experience with Spread and I don't want to repeat. I hated Spread as it was buggy and unstable. So I looked into other alternatives: XMPP, STOMP and AMQP. AMQP has no Perl client so it was out. STOMP and XMPP are closely tied in my view but then STOMP looked simplier so I decided to go with STOMP. There is very good Perl client library for STOMP: Net::STOMP.
# send a message to the queue 'foo'
use Net::Stomp;
my $stomp = Net::Stomp->new( { hostname => 'localhost', port => '61613' } );
$stomp->connect( { login => 'hello', passcode => 'there' } );
$stomp->send(
{ destination => '/queue/foo', body => 'test message' } );
$stomp->disconnect;
# subscribe to messages from the queue 'foo'
use Net::Stomp;
my $stomp = Net::Stomp->new( { hostname => 'localhost', port => '61613' } );
$stomp->connect( { login => 'hello', passcode => 'there' } );
$stomp->subscribe(
{ destination => '/queue/foo',
'ack' => 'client',
'activemq.prefetchSize' => 1
}
);
while (1) {
my $frame = $stomp->receive_frame;
warn $frame->body; # do something here
$stomp->ack( { frame => $frame } );
}
$stomp->disconnect;
Erlang debugging tips
I've just started playing with Erlang so I have a lot to discover but so far I've found several things which help me to debug my programs:STL strings vs C strings for parsing
I'm working on a project where I need to build custom high performance HTTP server. One piece of this server is a parser for URLs in incoming requests. It is very simple and on the first glance it shouldn't be that slow compared with other parts of the server. Yet it was taking quite a lot of CPU according to the profiler. The parser is using STL and basically does several string::find() calls to find parts of URL. So I thought maybe string::find() is too slow and decided to benchmark it against strchr(). This is my benchmark code:
#include <string.h>
#include <string>
#include <time.h>
#include <iostream>
using std::string;
using std::cout;
int main() {
const char* str1 = " a ";
const string& str2 = str1;
const unsigned long iterations = 500000000l;
{
clock_t start = clock();
for (unsigned long i = 0; i < iterations; ++i) {
char* pos = strchr(str1, 'a');
}
clock_t end = clock();
double totalTime = ((double) (end - start)) / CLOCKS_PER_SEC;
double iterTime = totalTime / iterations;
double rate = 1 / iterTime;
cout << "Total time: " << totalTime << " sec\n";
cout << "Iterations: " << iterations << " it\n";
cout << "Time per iteration: " << iterTime * 1000 << " msec\n";
cout << "Rate: " << rate << " it/sec\n";
}
{
clock_t start = clock();
for (unsigned long i = 0; i < iterations; ++i) {
string::size_type pos = str2.find('a');
}
clock_t end = clock();
double totalTime = ((double) (end - start)) / CLOCKS_PER_SEC;
double iterTime = totalTime / iterations;
double rate = 1 / iterTime;
cout << "Total time: " << totalTime << " sec\n";
cout << "Iterations: " << iterations << " it\n";
cout << "Time per iteration: " << iterTime * 1000 << " msec\n";
cout << "Rate: " << rate << " it/sec\n";
}
}
ilya@denmark:~$ g++ -O3 test.cc && ./a.out
Total time: 0 sec
Iterations: 500000000 it
Time per iteration: 0 msec
Rate: inf it/sec
Total time: 15.5 sec
Iterations: 500000000 it
Time per iteration: 3.1e-05 msec
Rate: 3.22581e+07 it/sec
ilya@denmark:~$ g++ -O2 test.cc && ./a.out
Total time: 0 sec
Iterations: 500000000 it
Time per iteration: 0 msec
Rate: inf it/sec
Total time: 15.76 sec
Iterations: 500000000 it
Time per iteration: 3.152e-05 msec
Rate: 3.17259e+07 it/sec
ilya@denmark:~$ g++ -O1 test.cc && ./a.out
Total time: 0 sec
Iterations: 500000000 it
Time per iteration: 0 msec
Rate: inf it/sec
Total time: 19.23 sec
Iterations: 500000000 it
Time per iteration: 3.846e-05 msec
Rate: 2.6001e+07 it/sec
ilya@denmark:~$ g++ -O0 test.cc && ./a.out
Total time: 18.64 sec
Iterations: 500000000 it
Time per iteration: 3.728e-05 msec
Rate: 2.6824e+07 it/sec
Total time: 16.89 sec
Iterations: 500000000 it
Time per iteration: 3.378e-05 msec
Rate: 2.96033e+07 it/sec
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