How to log a method s execution time exactly in milliseconds

Question

Is there a way to determine how much time a method needs to execute  in milliseconds

User · Answer

For fine-grained timing on OS X  you should use mach absolute time    declared in  lt mach mach time h gt     include  lt mach mach time h gt   include  lt stdint h gt      Do some stuff to setup for timing const uint64 t startTime   mach absolute time       Do some stuff that you want to time const uint64 t endTime   mach absolute time        Time elapsed in Mach time units  const uint64 t elapsedMTU   endTime - startTime      Get information for converting from MTU to nanoseconds mach timebase info data t info  if  mach timebase info  amp info      handleErrorConditionIfYoureBeingCareful        Get elapsed time in nanoseconds  const double elapsedNS    double elapsedMTU    double info numer    double info denom    Of course the usual caveats about fine-grained measurements apply  you re probably best off invoking the routine under test many times  and averaging taking a minimum some other form of processing   Additionally  please note that you may find it more useful to profile your application running using a tool like Shark   This won t give you exact timing information  but it will tell you what percentage of the application s time is being spent where  which is often more useful  but not always

User · Answer

I know this is an old one but even I found myself wandering past it again  so I thought I d submit my own option here   Best bet is to check out my blog post on this  Timing things in Objective-C  A stopwatch  Basically  I wrote a class that does stop watching in a very basic way but is encapsulated so that you only need to do the following    MMStopwatchARC start   My Timer       your work here      MMStopwatchARC stop   My Timer      And you end up with   MyApp 4090 15203   - gt  Stopwatch   My Timer  runtime   0 029    in the log     Again  check out my post for a little more or download it here  MMStopwatch zip

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many answers are weird and don t really give result in milliseconds  but in seconds or anything else    here what I use to get MS  MILLISECONDS    Swift   let startTime   NSDate   timeIntervalSince1970   1000     your Swift code  let endTimeMinusStartTime   NSDate   timeIntervalSince1970   1000 - startTime print  time code execution   endTimeMinStartTime  ms     Objective-C   double startTime     NSDate date  timeIntervalSince1970    1000 0      your Objective-C code  double endTimeMinusStartTime     NSDate date  timeIntervalSince1970    1000 0 - startTime  printf  time code execution  f ms n   endTimeMinusStartTime

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I use this in my utils library  Swift 4 2    public class PrintTimer       let start   Date       let name  String      public init file  String  file  line  Int  line  function  String  function  name  String  nil            let file   file split separator       last          self name   name       file    line  -   function              public func done             let end   Date           print    self name  took    end timeIntervalSinceReferenceDate - self start timeIntervalSinceReferenceDate  roundToSigFigs 5   s                  then call in a method like   func myFunctionCall         let timer   PrintTimer                  timer done           which in turn looks like this in the console after running   MyFile swift 225 - myFunctionCall   took 1 8623 s    Not as concise as TICK TOCK above  but it is clear enough to see what it is doing and automatically includes what is being timed  by file  line at the start of the method  and function name   Obviously if I wanted more detail  ex  if I m not just timing a method call as is the usual case but instead am timing a block within that method  I can add the  name  Foo   parameter on the PrintTimer init to name it something besides the defaults

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An example of fine-grained timing using mach absolute time   in Swift 4   let start   mach absolute time       do something  let elapsedMTU   mach absolute time   - start var timebase   mach timebase info   if mach timebase info  amp timebase     0       let elapsed   Double elapsedMTU    Double timebase numer    Double timebase denom      print  render took   elapsed      else       print  timebase error

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I use very minimal  one page class implementation inspired by code from this blog post    import  lt mach mach time h gt    interface DBGStopwatch   NSObject     void start  NSString   name     void stop  NSString   name    end   implementation DBGStopwatch     NSMutableDictionary   watches       static NSMutableDictionary  Watches   nil      static dispatch once t OnceToken      dispatch once  amp OnceToken             Watches       mutableCopy              return Watches        double secondsFromMachTime  uint64 t time       mach timebase info data t timebase      mach timebase info  amp timebase       return  double time    double timebase numer            double timebase denom   1e9        void start  NSString   name       uint64 t begin   mach absolute time        self watches name      begin         void stop  NSString   name       uint64 t end   mach absolute time        uint64 t begin    self watches name  unsignedLongLongValue       DDLogInfo   Time taken for     g s                 name   self secondsFromMachTime  end - begin          self watches removeObjectForKey name       end   The usage of it is very simple     just call  DBGStopwatch start   slow-operation    at the beginning and then  DBGStopwatch stop   slow-operation    after the finish  to get the time

User · Answer

There is a convenient wrapper for mach absolute time       it s a CACurrentMediaTime   function      Unlike NSDate or CFAbsoluteTimeGetCurrent   offsets    mach absolute time   and CACurrentMediaTime   are based on the   internal host clock  a precise  monatomic measure  and not subject to   changes in the external time reference  such as those caused by time   zones  daylight savings  or leap seconds      ObjC  CFTimeInterval startTime   CACurrentMediaTime       Do your stuff here CFTimeInterval endTime   CACurrentMediaTime    NSLog   Total Runtime   g s   endTime - startTime     Swift  let startTime   CACurrentMediaTime      Do your stuff here let endTime   CACurrentMediaTime   print  Total Runtime    endTime - startTime  s

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You can get really fine timing  seconds parts of seconds  using this StopWatch class   It uses the high-precision timer in the iPhone   Using NSDate will only get you second s  accuracy   This version is designed specifically for autorelease and objective-c   I have a c   version as well if needed   You can find the c   version here   StopWatch h   import  lt Foundation Foundation h gt     interface StopWatch   NSObject        uint64 t  start      uint64 t  stop      uint64 t  elapsed     - void  Start  - void  Stop  - void  StopWithContext  NSString   context  - double  seconds  - NSString   description    StopWatch   stopWatch  - StopWatch   init   end   StopWatch m   import  StopWatch h   include  lt mach mach time h gt    implementation StopWatch  - void  Start        stop   0       elapsed   0       start   mach absolute time      - void  Stop        stop   mach absolute time           if  stop  gt   start                 elapsed    stop -  start            else                 elapsed   0             start   mach absolute time       - void  StopWithContext  NSString   context        stop   mach absolute time           if  stop  gt   start                 elapsed    stop -  start            else                 elapsed   0            NSLog  NSString stringWithFormat        Stopped at  f  context  self seconds           start   mach absolute time        - double  seconds       if  elapsed  gt  0                uint64 t elapsedTimeNano   0           mach timebase info data t timeBaseInfo          mach timebase info  amp timeBaseInfo           elapsedTimeNano    elapsed   timeBaseInfo numer   timeBaseInfo denom          double elapsedSeconds   elapsedTimeNano   1 0E-9          return elapsedSeconds            return 0 0    - NSString   description       return  NSString stringWithFormat    f secs    self seconds        StopWatch   stopWatch       StopWatch  obj      StopWatch alloc  init  autorelease       return obj    - StopWatch   init        super   init       return self      end   The class has a static stopWatch method that returns an autoreleased object     Once you call start  use the seconds method to get the elapsed time   Call start again to restart it   Or stop to stop it   You can still read the time  call seconds  anytime after calling stop   Example In A Function   Timing call of execution   - void SomeFunc      StopWatch  stopWatch    StopWatch stopWatch       stopWatch Start           do stuff      stopWatch StopWithContext  NSString stringWithFormat   Created  d Records   records count

User · Answer

Here s a Swift 3 solution for bisecting code anywhere to find a long running process    var increment  Int   0  var incrementTime   NSDate    struct Instrumentation       var title  String     var point  Int     var elapsedTime  Double      init   title  String    point  Int    elapsedTime  Double            self title   title         self point   point         self elapsedTime   elapsedTime          var elapsedTimes    Instrumentation        func instrument   title  String        increment    1     let incrementedTime   -incrementTime timeIntervalSinceNow     let newPoint   Instrumentation title  increment  incrementedTime      elapsedTimes append newPoint      incrementTime   NSDate       Usage  -  instrument  View Did Appear    print  ELAPSED TIMES   elapsedTimes      Sample output -     ELAPSED TIMES  MyApp SomeViewController Instrumentation title   Start View   Did Load   point  1  elapsedTime  0 040504038333892822     MyApp SomeViewController Instrumentation title   Finished Adding   SubViews   point  2  elapsedTime  0 010585010051727295     MyApp SomeViewController Instrumentation title   View Did Appear     point  3  elapsedTime  0 56564098596572876

User · Answer

OK  if your objective is to find out what you can fix to make it faster  that s a little different goal  Measuring the time that functions take is a good way to find out if what you did made a difference  but to find out what to do you need a different technique  This is what I recommend  and I know you can do it on iPhones   Edit  Reviewers suggested I elaborate the answer  so I m trying to think of a brief way to say it  Your overall program takes enough clock time to bother you  Suppose that s N seconds  You re assuming you can speed it up  The only way you can do that is by making it not do something it s doing in that time  accounting for m seconds  You don t initially know what that thing is  You can guess  as all programmers do  but it could easily be something else  Whatever it is  here s how you can find it   Since that thing  whatever it is  accounts for fraction m N of the time  that means if you pause it at random the probability is m N that you will catch it in the act of doing that thing  Of course it might be doing something else  but pause it and see what it s doing  Now do it again  If you see it doing that same thing again  you can be more suspicious   Do it 10 times  or 20  Now if you see it doing some particular thing  no matter how you describe it  on multiple pauses  that you can get rid of  you know two things  You know very roughly what fraction of time it takes  but you know very exactly what to fix  If you also want to know very exactly how much time will be saved  that s easy  Measure it before  fix it  and measure it after  If you re really disappointed  back out the fix   Do you see how this is different from measuring  It s finding  not measuring  Most profiling is based on measuring as exactly as possible how much time is taken  as if that s important  and hand-waves the problem of identifying what needs to be fixed  Profiling does not find every problem  but this method does find every problem  and it s the problems you don t find that hurt you

User · Answer

Here is another way  in Swift  to do that using the defer keyword  func methodName       let methodStart   Date     defer       let executionTime   Date   timeIntervalSince methodStart      print  Execution time    executionTime             do your stuff here     From Apple s docs  A defer statement is used for executing code just before transferring program control outside of the scope that the defer statement appears in   This is similar to a try finally block with the advantage of having the related code grouped

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Here are two one-line macros that I use    define TICK   NSDate  startTime    NSDate date   define TOCK   NSLog   Time   f   - startTime timeIntervalSinceNow     Use it like this   TICK          Do Some Work Here         TOCK

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In Swift  I m using  In my Macros swift I just added var startTime   NSDate   func TICK    startTime    NSDate     func TOCK function  String     FUNCTION    file  String     FILE    line  Int     LINE         println  quot   function  Time    startTime timeIntervalSinceNow  nLine   line  File    file  quot      you can now just call anywhere TICK       your code to be tracked  TOCK    Swift 5 0    var startTime   NSDate   func TICK    startTime    NSDate     func TOCK function  String    function  file  String    file  line  Int    line       print  quot   function  Time    startTime timeIntervalSinceNow  nLine   line  File    file  quot       this code is based on Ron s code translate to Swift  he has the credits I m using start date at global level  any suggestion to improve are welcome

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Since you want to optimize time moving from one page to another in a UIWebView  does it not mean you really are looking to optimize the Javascript used in loading these pages   To that end  I d look at a WebKit profiler like that talked about here   http   www alertdebugging com 2009 04 29 building-a-better-javascript-profiler-with-webkit   Another approach would be to start at a high level  and think how you can design the web pages in question to minimize load times using AJAX style page loading instead of refreshing the whole webview each time

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For Swift 4  add as a Delegate to your class   public protocol TimingDelegate  class       var  TICK  Date   get set      extension TimingDelegate       var TICK  Date            TICK   Date           return  TICK               func TOCK message  String              if   TICK    nil               print  Call  TICK  first                       if  message                     print    Date   timeIntervalSince  TICK                        else              print    message     Date   timeIntervalSince  TICK                          Add to our class   class MyViewcontroller  UIViewController  TimingDelegate   Then add to your class   var  TICK  Date    When you want to time something  start with   TICK   And end with   TOCK  Timing the XXX routine

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I use this code    import  lt mach mach time h gt   float TIME BLOCK NSString  key  void   block  void         mach timebase info data t info      if  mach timebase info  amp info     KERN SUCCESS                return -1 0             uint64 t start   mach absolute time        block        uint64 t end   mach absolute time        uint64 t elapsed   end - start       uint64 t nanos   elapsed   info numer   info denom      float cost    float nanos   NSEC PER SEC       NSLog   key       f ms  n   key  cost   1000       return cost

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struct TIME        static var ti   mach timebase info       static var k  Double   1     static var mach stamp  Double            if ti denom    0               mach timebase info  amp ti              k   Double ti numer    Double ti denom    1e-6                   return Double mach absolute time      k           static var stamp  Double   return NSDate timeIntervalSinceReferenceDate     1000      do       let mach start   TIME mach stamp     usleep 200000      let mach diff   TIME mach stamp - mach start      let start   TIME stamp     usleep 200000      let diff   TIME stamp - start      print mach diff  diff

User · Answer

NSDate  methodStart    NSDate date           Do whatever you need to do         NSDate  methodFinish    NSDate date   NSTimeInterval executionTime    methodFinish timeIntervalSinceDate methodStart   NSLog   executionTime    f   executionTime     Swift   let methodStart   NSDate           Do whatever you need to do         let methodFinish   NSDate   let executionTime   methodFinish timeIntervalSinceDate methodStart  print  Execution time    executionTime      Swift3   let methodStart   Date           Do whatever you need to do         let methodFinish   Date   let executionTime   methodFinish timeIntervalSince methodStart  print  Execution time    executionTime      Easy to use and has sub-millisecond precision

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I use this   clock t start  end  double elapsed  start   clock       Start code to time    End code to time  end   clock    elapsed     double   end - start     CLOCKS PER SEC  NSLog   Time   f  elapsed     But I m not sure about CLOCKS PER SEC on the iPhone  You might want to leave it off

User · Answer

I use macros based on Ron s solution    define TICK XXX  NSDate  XXX    NSDate date   define TOCK XXX  NSLog    s   f    XXX  - XXX timeIntervalSinceNow     For lines of code   TICK TIME1       do job here TOCK TIME1     we ll see in console something like  TIME1  0 096618

[ios] How to log a method's execution time exactly in milliseconds?

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