Thanks.

So will you combine

select(1024,{ 3 },{ },{ },{ 0.000000 }) select(1024,{ },{ },{ },{ 0.010000 })

in

select(1024,{ 3 },{ },{ },{ 0.010000 })

?

And

select(1024,{ },{ },{ },{ 0.010000 }) poll({ 3/POLLIN },1,0)

in

poll({ 3/POLLIN },1, 0.010000)

?

And will you make this time (0.010000) adjustable also?

And one more question. Please tell me, how to do it better. I want cancel Socket.accept (Socket.recvVec, ...) call by signal or timeout. For this I use loop select with 1 second timeout and check signal flag. See code below. It is duplication with repeatedly polling of PolyML. Is it possible to make some kind of flag to tell to PolyML to cancel repeatedly polling?

val stop = ref false val _ = Signal.signal (Posix.Signal.term, Signal.SIG_HANDLE (fn _ => stop := true))

fun accept socket = let val t = Time.fromSeconds 1 val sd = Socket.sockDesc socket fun doit socket = case Socket.select { rds = [sd], wrs = [], exs = [], timeout = SOME t } of { rds = [sd], wrs = [], exs = [] } => (case Socket.acceptNB socket of NONE (* Other worker was first *) => doit socket | r => r) | _ => if !stop then NONE else doit socket in doit socket end

(* return "" if timeout or stop *) fun read (socket, chunksize, (timeout:Time.time option)) = let val t = Time.fromSeconds 1 val sd = Socket.sockDesc socket fun doit timeout = case Socket.select { rds = [sd], wrs = [], exs = [], timeout = SOME t } of { rds = [sd], wrs = [], exs = [] } => Byte.bytesToString (Socket.recvVec (socket, chunksize)) | _ => ( case timeout of NONE => doit NONE | SOME tt => if Time.>(tt, t) then doit (SOME (Time.-(tt, t))) else "" ) in doit timeout handle OS.SysErr ("Interrupted system call", _) => if !stop then "" else doit timeout | exc => raise exc end ??, 13 ???. 2018 ?. ? 16:54, David Matthews <David.Matthews at prolingua.co.uk>:

What you are seeing is Poly/ML repeatedly polling then blocking for a short while. It doesn't use a blocking call or a long time-out because with multi-threading there's the possibility that another thread might interrupt it, perhaps as the result of a console interrupt.

Actually, looking at the code I think it could be improved. I'll have a look at it.

David

On 13/12/2018 09:01, Kostirya wrote:

...

Hello. My application use select or poll before accept socket. I trace system calls and found that too many select or poll calls occur.

When I use select:

select(1024,{ },{ },{ },{ 0.010000 }) = 0 (0x0) select(1024,{ 3 },{ },{ },{ 0.000000 }) = 0 (0x0) select(1024,{ },{ },{ },{ 0.010000 }) = 0 (0x0) select(1024,{ 3 },{ },{ },{ 0.000000 }) = 0 (0x0) select(1024,{ },{ },{ },{ 0.010000 }) = 0 (0x0) ... select(1024,{ 3 },{ },{ },{ 0.000000 }) = 1 (0x1) accept(3,{ AF_INET 127.0.0.1:54121 },0xbb9f9c5c) = 4 (0x4)

When I use poll and do *not* select:

poll({ 3/POLLIN },1,0) = 0 (0x0) select(1024,{ },{ },{ },{ 0.010000 }) = 0 (0x0) poll({ 3/POLLIN },1,0) = 0 (0x0) select(1024,{ },{ },{ },{ 0.010000 }) = 0 (0x0) poll({ 3/POLLIN },1,0) = 0 (0x0) select(1024,{ },{ },{ },{ 0.010000 }) = 0 (0x0) poll({ 3/POLLIN },1,0) = 1 (0x1) ... accept(3,{ AF_INET 127.0.0.1:48659 },0xbb9f9c5c) = 4 (0x4)

My application wait incoming connection and do nothing but use 1-2% CPU.

What is it and why it is?

By the way. When I use kevent (epoll on linux) via FFI it is all right.

Nick. _______________________________________________ polyml mailing list polyml at inf.ed.ac.uk http://lists.inf.ed.ac.uk/mailman/listinfo/polyml

Excellent! It solved my problem.

I use FreeBSD (my main OS) and also Linux. To trace system calls I use truss for FreeBSD and strace for Linux. Branch "SelectPoll" was tested on FreeBSD and Linux. It is all right! Also I have tested by help my http server under high loading. I think you can do merge branch "SelectPoll" into master.

Thank you very match! Nick.

??, 13 ???. 2018 ?. ? 21:39, David Matthews <David.Matthews at prolingua.co.uk>:

I've pushed some changes to a separate branch "SelectPoll" in the Poly/ML Git repository. Could you try it out and let me know if it seems to solve your problem? It combines the calls and also increases the time-out to 1 second. How exactly did you get the trace of system calls? Which operating system are you using?

You could change your signal handler to interrupt the select by using Thread.Thread.interrupt. That will raise Thread.Thread.interrupt in the "select" calls. To be safe you should probably set the main thread to use InterruptSynch.

David

On 13/12/2018 15:40, Kostirya wrote:

...

Thanks.

So will you combine

select(1024,{ 3 },{ },{ },{ 0.000000 }) select(1024,{ },{ },{ },{ 0.010000 })

in

select(1024,{ 3 },{ },{ },{ 0.010000 })

?

And

select(1024,{ },{ },{ },{ 0.010000 }) poll({ 3/POLLIN },1,0)

in

poll({ 3/POLLIN },1, 0.010000)

?

And will you make this time (0.010000) adjustable also?

And one more question. Please tell me, how to do it better. I want cancel Socket.accept (Socket.recvVec, ...) call by signal or timeout. For this I use loop select with 1 second timeout and check signal flag. See code below. It is duplication with repeatedly polling of PolyML. Is it possible to make some kind of flag to tell to PolyML to cancel repeatedly polling?

val stop = ref false val _ = Signal.signal (Posix.Signal.term, Signal.SIG_HANDLE (fn _ => stop := true))

fun accept socket = let val t = Time.fromSeconds 1 val sd = Socket.sockDesc socket fun doit socket = case Socket.select { rds = [sd], wrs = [], exs = [], timeout = SOME t } of { rds = [sd], wrs = [], exs = [] } => (case Socket.acceptNB socket of NONE (* Other worker was first *) => doit socket | r => r) | _ => if !stop then NONE else doit socket in doit socket end

(* return "" if timeout or stop *) fun read (socket, chunksize, (timeout:Time.time option)) = let val t = Time.fromSeconds 1 val sd = Socket.sockDesc socket fun doit timeout = case Socket.select { rds = [sd], wrs = [], exs = [], timeout = SOME t } of { rds = [sd], wrs = [], exs = [] } => Byte.bytesToString (Socket.recvVec (socket, chunksize)) | _ => ( case timeout of NONE => doit NONE | SOME tt => if Time.>(tt, t) then doit (SOME (Time.-(tt, t))) else "" ) in doit timeout handle OS.SysErr ("Interrupted system call", _) => if !stop then "" else doit timeout | exc => raise exc end ??, 13 ???. 2018 ?. ? 16:54, David Matthews <David.Matthews at prolingua.co.uk>:

...

What you are seeing is Poly/ML repeatedly polling then blocking for a short while. It doesn't use a blocking call or a long time-out because with multi-threading there's the possibility that another thread might interrupt it, perhaps as the result of a console interrupt.

Actually, looking at the code I think it could be improved. I'll have a look at it.

David

On 13/12/2018 09:01, Kostirya wrote:

...

Hello.
My application use select or poll before accept socket.
I trace system calls and found that too many select or poll calls occur.

When I use select:

select(1024,{ },{ },{ },{ 0.010000 })            = 0 (0x0)
select(1024,{ 3 },{ },{ },{ 0.000000 })          = 0 (0x0)
select(1024,{ },{ },{ },{ 0.010000 })            = 0 (0x0)
select(1024,{ 3 },{ },{ },{ 0.000000 })          = 0 (0x0)
select(1024,{ },{ },{ },{ 0.010000 })            = 0 (0x0)
...
select(1024,{ 3 },{ },{ },{ 0.000000 })          = 1 (0x1)
accept(3,{ AF_INET 127.0.0.1:54121 },0xbb9f9c5c) = 4 (0x4)


When I use poll and do *not* select:

poll({ 3/POLLIN },1,0)                 = 0 (0x0)
select(1024,{ },{ },{ },{ 0.010000 })         = 0 (0x0)
poll({ 3/POLLIN },1,0)                 = 0 (0x0)
select(1024,{ },{ },{ },{ 0.010000 })         = 0 (0x0)
poll({ 3/POLLIN },1,0)                 = 0 (0x0)
select(1024,{ },{ },{ },{ 0.010000 })         = 0 (0x0)
poll({ 3/POLLIN },1,0)                 = 1 (0x1)
...
accept(3,{ AF_INET 127.0.0.1:48659 },0xbb9f9c5c) = 4 (0x4)


My application wait incoming connection and do nothing but use 1-2% CPU.

What is it and why it is?

By the way.
When I use kevent (epoll on linux) via FFI it is all right.

Nick.

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