Create thread pool to read multiple files in parallel

i need to create a thread pool, from which i can read up to 10 files at a time in parallel.

and for each thread reads a file it must  insert into another shared text file its id and some text ( for example "thread 1 reads file x").

i need to implement a locking mechanism on this shared file that ensures that only one thread may writes on it at a time, but multiple threads 

may read data from the shared file simultaneously. 

 

really i am new to threading programming, and i am confused about how to start.

waiting your help please :)