Awesome! : )
On Thu, Nov 10, 2011 at 12:38:47PM -0700, Matthew Flatt wrote: > I've pushed a change in the way that the Racket scheduler handles I/O. > The new implementation should scale to a large number of network > connections, at least on Linux and BSDs (including Mac OS X). > > > Formerly, if a program had many threads each blocked on on I/O, then > the scheduler would poll each thread separately to find one to run. At > the OS level, that polling amounted to one select() per blocked thread. > > Now, Racket internally suspends a thread that is blocked on I/O and > registers a callback via epoll()/kqueue() (where available). The > callback internally resumes specific threads when I/O becomes > available; meanwhile, the thread scheduler doesn't poll or otherwise > consider threads that are blocked on I/O. > > Similar benefits apply when multiple I/O events are grouped together in > a `sync'. The old implementation polled each item in the `sync' > individually, and the new one uses epoll()/kqueue(). > > > I'm interested to hear whether this change has any effect on real > uses of Racket. > > One simple benchmark is below: it creates 100 blocked UDP sockets, each > with its own blocked thread, and then it trades 1 byte 10k times > between two threads via TCP (which forces constant thread swaps). Even > with only 100 blocked sockets, the new Racket is 2-3 times as fast on > my Mac OS X and Linux machines (the latter on VirtualBox). With 1000 > blocked sockets, the new Racket takes about the same time as with 100, > while the old Racket takes longer than I'm willing to wait. > > I've tried more realistic benchmarks, such as creating N TCP > connections, each with a blocked thread on the server side, and then > looping to accept M new connections (with a read followed by a close > for each new connection). The new Racket seems to scale for large N > while the old Racket doesn't. > > ---------------------------------------- > > #lang racket > > (define N 100) > (define M 10000) > > (define l (tcp-listen 40000 5 #t)) > > (thread > (lambda () > ;; Generate stuck sockets: > (for ([i (in-range N)]) > (define u (udp-open-socket)) > (udp-bind! u #f 0) > (thread (lambda () (udp-receive! u (make-bytes 10))))) > ;; Time communication (server side): > (define-values (ci co) (tcp-accept l)) > (for ([i (in-range M)]) > (write-byte (modulo i 127) co) > (flush-output co) > (read-byte ci)))) > > ;; Time communication (client side): > (define-values (ci co) (tcp-connect "localhost" 40000)) > (time > (for ([i (in-range M)]) > (read-byte ci) > (write-byte 7 co) > (flush-output co))) > > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/dev _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
