#20 Write stats collecting mechanism

Nedd #24

Find a way to collect stats in pool_handling process.

The collection mechanism should give access to UDP server ( see #19 ) to following data :

• worker count
• requests count last 10/5/1 minute
• request time average (maybe ?) => slow IPC between worker & pool ?
• total request counter (maybe ?) => will overflow ?!
• idle/busy state (maybe ?) => change too fast ?
• idle/busy ratio or workload (maybe ?)

We have to take care of not slowing down the workers with this component…

Maybe the collection child could help implementing this mechanism ?

A solution to a fast request counter implementation can use semaphores :

When a worker starts handling a request it increment a sempahore. Meanwhile, a counter process (pool_handler or stats collection child) will attempt to decrease (fast enough) the semaphore with WNOHANG.

If the decrement semop do not fail, a counter can be incremented.

Note : the 10/5/1 min counters implies to store all requests timestamps ?? Maybe we can associate a timestamp with a request count ?

=> if 100 req/s stores {time(NULL), 100} and not time_t [100] = {time(NULL), time(NULL), etc.}

closed by b3af92459e