Yes, it's best to avoid concatenating strings with +. Not only for performance
reasons, but it's also less readable than string interpolation:
str += "No: \(count), HostIp: \(clientIp ?? "?") at port: \(service ?? "?")\n"
> On 23 Mar 2017, at 08:11, Rien via swift-users <swift-users@swift.org> wrote:
>
> Thanks for that link, used it to track down the worst compile time offender:
>
> This piece of code:
>
> public func logAddrInfoIPAddresses(_ infoPtr: UnsafeMutablePointer<addrinfo>)
> -> String {
>
> let addrInfoNil: UnsafeMutablePointer<addrinfo>? = nil
> var count: Int = 0
> var info: UnsafeMutablePointer<addrinfo> = infoPtr
> var str: String = ""
>
> while info != addrInfoNil {
>
> let (clientIp, service) = sockaddrDescription(info.pointee.ai_addr)
> str += "No: \(count), HostIp: " + (clientIp ?? "?") + " at port: " +
> (service ?? "?") + "\n"
> count += 1
> info = info.pointee.ai_next
> }
> return str
> }
>
> Took 38 seconds to compile.
>
> Removing the “str” assignment:
>
> public func logAddrInfoIPAddresses(_ infoPtr: UnsafeMutablePointer<addrinfo>)
> -> String {
>
> let addrInfoNil: UnsafeMutablePointer<addrinfo>? = nil
> var count: Int = 0
> var info: UnsafeMutablePointer<addrinfo> = infoPtr
> var str: String = ""
>
> while info != addrInfoNil {
>
> let (clientIp, service) = sockaddrDescription(info.pointee.ai_addr)
> // str += "No: \(count), HostIp: " + (clientIp ?? "?") + " at port: "
> + (service ?? "?") + "\n"
> count += 1
> info = info.pointee.ai_next
> }
> return str
> }
>
> Brought it down to 6.6ms
>
> Obviously I have to rewrite, but it does show how just one line of code can
> be responsible for approx 80% of the compile time.
>
> Regards,
> Rien
>
> Site: http://balancingrock.nl
> Blog: http://swiftrien.blogspot.com
> Github: http://github.com/Balancingrock
> Project: http://swiftfire.nl
>
>
>
>
>
>>> On 22 Mar 2017, at 23:41, Greg Parker via swift-users
>>> <swift-users@swift.org> wrote:
>>>
>>>
>>> On Mar 22, 2017, at 1:03 PM, piotr gorzelany via swift-users
>>> <swift-users@swift.org> wrote:
>>>
>>> Hi, I hope I reached the right mailing list to ask a question about tooling.
>>>
>>> Can somebody from the compiler or Xcode team share some tips on how to
>>> improve compilation times of larger Swift projects?
>>>
>>> I am an iOS developer and the largest issue my team has with Swift so far
>>> is that when the project gets semi large (~30 000 lines) the compilation
>>> times start to be high (~10 minutes from clean). This is a MAJOR downside
>>> since iOS development oftentimes requires rapid changes to UI or logic.
>>> Every person of my team compiles a project at least 10 times a day to test
>>> new features or functionalities. When compilation times start to be higher
>>> than 10 minutes that gets us to ~1.5h a day of developer time spend just on
>>> compiling. Not to mention the focus lost when this is happening.
>>>
>>> I know the Swift Evolution list is buzzing with new ideas and features but
>>> from my experience the compilation times is a CRITICAL thing to improve in
>>> the next Swift release since it cost real money to waste all those
>>> developer hours. Just think of all the hours lost on compiling across all
>>> Swift devs worldwide and you will get to probably dozens of thousand of dev
>>> hours a day.
>>>
>>> Is the core compiler team going to address compilation performance in the
>>> next release?
>>>
>>> Maybe there is an existing solution to long compilation times that we don't
>>> know of? It would be great if anybody could share.
>>> I was thinking maybe of dividing the app into multiple frameworks since I
>>> think frameworks are compiled only once only on change?
>>
>> Build time is always a goal. Pretty much every version of Swift has had
>> changes intended to improve compilation time or decrease the frequency of
>> recompilation.
>>
>> Often a large part of the build time is spent in a handful of places where
>> the compiler's type inference system behaves poorly. You can use the
>> -debug-time-function-bodies and -debug-time-expression-type-checking flags
>> to look for these places. You can often get huge decreases in compile time
>> by adding an explicit type declaration in the right place in order to
>> simplify the type inference engine's job.
>>
>> Here's a walkthough of one such analysis:
>> Profiling your Swift compilation times
>> http://irace.me/swift-profiling
>>
>>
>> --
>> Greg Parker gpar...@apple.com Runtime Wrangler
>>
>>
>> _______________________________________________
>> swift-users mailing list
>> swift-users@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-users
>
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