Process based code vs. Thread based code

[rkalyankumar]

I am just wondering on which is the best way to write programs on UNIX. Which one is better from below:

a) Spawning threads per client connection/request?
b) fork-exec new processes per client connection/request?

Assume that I am doing some database system on linux which is supposed to run on unix systems as well.

The basic differences as I know are:

Using processes - have it's own address space, communicate using SysV/POSIX shared memory + semaphores etc & context switching is costly. Also implementing processes instead of threads is that process are more stable and reliable than threads. Just because if one thread malfunctions, the entire process would break.

On the other side, using thread the context switching is less cheaper compared to that of process context switches. No need for shared memory as the memory is shared and accessible by all threads with in the process & hence can avoid costly IPC mechanism's like SysV/POSIX shared memory and semaphores. Instead use simple mutexes and condition variables.

Being said all the above, I am still not in a position to decide up on which way to go i.e. use threads or use processes?

Please help.

Regards
Kalyan