| Thanks again. I have given numbers in my original message.
Messages are limited in size 1000 bytes. I have up to 3 instances of my bidirectional socket. - Audio Video and some variant of screen-sharing (similar in behavior to Video). Audio socket can receive up to 100 messages a second - each message exactly 84 bytes. Video (and the third) will regularly receive ~30 messages a second, each message up to 1000 bytes, but can momentarily rise to 100 messages a second.
This means I can roughly expect to call read:maxLength: about 60 - 200 times a second If I’m to abandon my ring buffer.
The other side - allocating and copying incoming messages off my ring-buffer, is also a little extensive. Parsing the messages is very fast and negligible (merely cast a C-struct over the message pointer). I then perform some complicated logic over the parsed messages - but this logic cannot change whatever socket implementation I choose. Then I need to serially pass these messages serially (not concurrently) to an external media engine, that will - again - copy them into its own queues, and will process them in its internal threads. From experiments and using instruments, I learned it’s not very fast with taking in my messages.
This is not a high-performance situation - but my socket supports iOS and Mac, with devices ranging from iPhone4 and iPad2 up to the latest Mac computers. On iPhone-4 we suffer performance issues today, and the socket implementation is responsible for at least some of it.
On Sep 17, 2015, at 2:24 AM, Motti Shneor < email@hidden> wrote:
Is there a specific penalty to NSStream’s method read:maxLength: ? If I call it on the average 2-3 times a message, Is this far worse than reading big bulks off the stream, then doing all my book-keeping and copying and locking?
It depends on how often you’re calling it, and the relative cost of reading vs parsing vs handling messages. In most use cases the kernel call overhead isn’t very significant. IIRC, you haven’t given us any specific numbers, or any indication that this is a super-high-performance situation.
Last, several guys mentioned GCDAsyncSocket. What is it? an open-source thing? a system API I’m not aware of?
Or alternatively, right-click on ‘GCDAsyncSocket’ and choose “Search With Google” from the context menu. I’m not trying to be snarky, just pointing out that these days asking “what is X” is usually slower than looking it up yourself.
—Jens
Motti Shneor, CEO, suMac LTD. Software Development for the Macintosh
Home/Office Address: 34 Emek-Ha-Ella St. Appt.1 Modiin, ISRAEL, 71723 Home/Office Tel/Fax: +972-8-9267730
Office eMail: email@hiddenMobile phone: +972-54-3136621
--- ceterum censeo microsoftiem delendam esse ---
|