Thursday, March 25, 2010

Thread stack in heap (pthreads)

I had known that a thread has a stack. But never thought where is this stack lie in the memory?

Well, it should be process stack. But you can set the thread stack to a heap area.

How to do that?

#include "pthread.h"
#include "stdio.h"
#include "unistd.h"

pthread_mutex_t mutex1;

void* foo(void *arg)
{
int arr[1024*8];

int x = 0;
while(x++ < (8*1024) )
{ arr[x] = x; }

pthread_mutex_lock(&mutex1);
puts("Thread created");
pthread_mutex_unlock(&mutex1);
}

int main()
{
int *p;
void *ret;

p = malloc(1024);

free(p);

pthread_attr_t attr;

pthread_attr_setstack(&attr, p, 2);

pthread_t thread1;

pthread_create(&thread1, NULL, foo, NULL);

pthread_join(thread1, &ret);

free(p);

return 0;
}

But still I am not very sure of this concept.

Stay tuned for more!

Monday, March 22, 2010

Some thoughts on Linux malloc()

* Always check for equal number of malloc()/free() calls.
• Use calloc() instead of malloc() + memset()
• Instead of allocation memory in a piece-meal manner, try to allocate a bigger chunk with malloc() and keep on resizing it with realloc() if needed.
• malloc() over-commits the memory i.e. it gives you an address which actually does not exist!
• malloc() grouping & reallocing with "more than you want"

Thursday, March 11, 2010

Cut short your web-addresses: TinyURL

An utility called "tinyurl" makes your life easier with shorter URL without creating an all new website. Many times it become cumbersome(i.e. for a long string) and unsafe(if you miss to copy contents of the link) to send a link to your friend.

TinyURl helps you with providing an alias for a long link. Concept is very simple but effective.
e.g. a link is: "http://http://www.blogger.com/post-create.g?blogID=4233584295994918105"

You may get an easier name for this link as: http://tinyurl.com/abc

Here is more information this:
http://tinyurl.com