Reduce startup time. #1288

dmaclach · 2018-12-18T04:11:02Z

Make global static a function local static. This stops it from being initialized premain and affecting startup time.

nguyenhuy · 2018-12-18T04:29:57Z

I think @Adlai-Holler mentioned that dispatch_once is faster than function local static because the latter uses a global mutex for all statics. Maybe switch to dispatch_once to get the tiny perf gain?

Make global static a function local static. This stops it from being initialized premain and affecting startup time.

maicki · 2018-12-18T06:01:55Z

I would be interested to get some benchmarks numbers around this area. @dmaclach Did you profile by any chance?

Looking at http://www.modernescpp.com/index.php/thread-safe-initialization-of-a-singleton it seems static vars with block scope is faster as using std::call_once what I would compare with dispatch_once.

maicki · 2018-12-18T14:43:37Z

I looked a bit more into benchmarking C++ static variables with block scope and dispatch_once initialization. Here is a small benchmark script and the results running it three times at the end. Pretty interesting based on the results we probably should go with dispatch_once:

#import <AppKit/AppKit.h>

extern "C" {
  extern uint64_t dispatch_benchmark(size_t count, void (^block)(void));
}

static NSArray *DefaultLinkAttributeNamesMagicStatic() {
  static NSArray *names = @[ NSLinkAttributeName ];
  return names;
}

static NSArray *DefaultLinkAttributeNamesMagicDispatchOnce() {
  static NSArray *names = nil;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    names = @[ NSLinkAttributeName ];
  });
  return names;
}

static void testDefaultLinkAttributeNamesMagicStatic(size_t iterations) {
  uint64_t t = dispatch_benchmark(iterations, ^{
    __unused NSArray *_ = DefaultLinkAttributeNamesMagicStatic();
  });
  NSLog(@"DefaultLinkAttributeNamesMagicStatic Avg. Runtime: %llu ns", t);
}

static void testDefaultLinkAttributeNamesMagicDispatchOnce(size_t iterations) {
  uint64_t t = dispatch_benchmark(iterations, ^{
    __unused NSArray *_ = DefaultLinkAttributeNamesMagicDispatchOnce();
  });
  NSLog(@"DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: %llu ns", t);
}

int main(int argc, const char * argv[]) {
  @autoreleasepool {
    size_t iterations = 100000;

    for (int i = 0; i < 5; i++) {
      testDefaultLinkAttributeNamesMagicStatic(iterations);
    }

    for (int i = 0; i < 5; i++) {
      testDefaultLinkAttributeNamesMagicDispatchOnce(iterations);
    }
  }
  return 0;
}

Runs:

1. Run:

2018-12-18 15:38:26.754728+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:38:26.759215+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:38:26.763499+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:38:26.767830+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 42 ns
2018-12-18 15:38:26.772055+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:38:26.775158+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:38:26.778210+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:38:26.781240+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:38:26.784296+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:38:26.787350+0100 StaticInitializerBenchmark[62817:763142] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns

2. Run:

2018-12-18 15:41:12.422922+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 40 ns
2018-12-18 15:41:12.427357+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:41:12.431553+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 40 ns
2018-12-18 15:41:12.435736+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 40 ns
2018-12-18 15:41:12.440016+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:41:12.443089+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:41:12.446144+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:41:12.449175+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:41:12.452215+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:41:12.455317+0100 StaticInitializerBenchmark[63262:768527] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns

3. Run:

2018-12-18 15:44:32.690212+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 42 ns
2018-12-18 15:44:32.694629+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:44:32.698876+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:44:32.703140+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:44:32.707375+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 41 ns
2018-12-18 15:44:32.710474+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:44:32.713577+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:44:32.716666+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:44:32.719714+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns
2018-12-18 15:44:32.722748+0100 StaticInitializerBenchmark[63835:775815] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 29 ns

maicki · 2018-12-18T14:57:14Z

Also interesting moving this to multithreading access via dispatch_apply:

int main(int argc, const char * argv[]) {
  @autoreleasepool {
    size_t iterations = 10000000;

    dispatch_apply(5, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(size_t size) {
      testDefaultLinkAttributeNamesMagicStatic(iterations);
    });
//    for (int i = 0; i < 5; i++) {
//      testDefaultLinkAttributeNamesMagicStatic(iterations);
//    }

    dispatch_apply(5, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(size_t size) {
      testDefaultLinkAttributeNamesMagicDispatchOnce(iterations);
    });
//    for (int i = 0; i < 5; i++) {
//      testDefaultLinkAttributeNamesMagicDispatchOnce(iterations);
//    }
  }
  return 0;
}

1. Run

2018-12-18 15:58:05.995261+0100 StaticInitializerBenchmark[66418:809388] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 910 ns
2018-12-18 15:58:06.001869+0100 StaticInitializerBenchmark[66418:809489] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 911 ns
2018-12-18 15:58:06.007117+0100 StaticInitializerBenchmark[66418:809491] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 911 ns
2018-12-18 15:58:06.109230+0100 StaticInitializerBenchmark[66418:809490] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 922 ns
2018-12-18 15:58:06.109656+0100 StaticInitializerBenchmark[66418:809492] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 922 ns
2018-12-18 15:58:12.715117+0100 StaticInitializerBenchmark[66418:809961] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 659 ns
2018-12-18 15:58:12.761388+0100 StaticInitializerBenchmark[66418:809963] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 664 ns
2018-12-18 15:58:12.845285+0100 StaticInitializerBenchmark[66418:809388] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 672 ns
2018-12-18 15:58:12.868158+0100 StaticInitializerBenchmark[66418:809960] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 674 ns
2018-12-18 15:58:12.883791+0100 StaticInitializerBenchmark[66418:809962] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 676 ns

2. Run:

2018-12-18 15:58:36.470113+0100 StaticInitializerBenchmark[66479:810703] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 899 ns
2018-12-18 15:58:36.508274+0100 StaticInitializerBenchmark[66479:810786] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 903 ns
2018-12-18 15:58:36.646166+0100 StaticInitializerBenchmark[66479:810799] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 917 ns
2018-12-18 15:58:36.666202+0100 StaticInitializerBenchmark[66479:810785] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 919 ns
2018-12-18 15:58:36.707457+0100 StaticInitializerBenchmark[66479:810798] DefaultLinkAttributeNamesMagicStatic Avg. Runtime: 923 ns
2018-12-18 15:58:43.947740+0100 StaticInitializerBenchmark[66479:811002] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 723 ns
2018-12-18 15:58:44.046547+0100 StaticInitializerBenchmark[66479:811001] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 732 ns
2018-12-18 15:58:44.054506+0100 StaticInitializerBenchmark[66479:810703] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 733 ns
2018-12-18 15:58:44.054509+0100 StaticInitializerBenchmark[66479:811000] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 733 ns
2018-12-18 15:58:44.055542+0100 StaticInitializerBenchmark[66479:810999] DefaultLinkAttributeNamesMagicDispatchOnce Avg. Runtime: 733 ns

dmaclach · 2018-12-18T16:39:58Z

Thanks folks. Moved over to dispatch_once.

nguyenhuy · 2018-12-18T16:59:52Z

Very interesting numbers, thanks for sharing @maicki.

nguyenhuy

LGTM now. It's great that we can reclaim some pre-main time. Thank you, @dmaclach!

dmaclach · 2018-12-18T17:08:30Z

FWIW

https://opensource.apple.com/source/libcppabi/libcppabi-26/src/cxa_guard.cxx.auto.html

Is how the static initialization is done. There does appear to be at large recursive lock.

maicki

@dmaclach Thanks for improving!

mikezucc · 2018-12-18T21:02:50Z

cool stuff!

dmaclach · 2018-12-18T21:46:02Z

@maicki can you merge? I do not have privs.

Make global static a function local static. This stops it from being initialized premain and affecting startup time. (cherry picked from commit 7cddc2b)

Reduce startup time.

258c094

Make global static a function local static. This stops it from being initialized premain and affecting startup time.

maicki closed this Dec 18, 2018

maicki reopened this Dec 18, 2018

nguyenhuy approved these changes Dec 18, 2018

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maicki approved these changes Dec 18, 2018

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nguyenhuy merged commit 7cddc2b into TextureGroup:master Dec 19, 2018

dmaclach deleted the static1 branch December 19, 2018 16:27

raviTokopedia mentioned this pull request Mar 6, 2020

Cherry Pick launch optimisation commits from Texture 2.8 jeffersonsetiawan/Texture#3

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Reduce startup time. #1288

Reduce startup time. #1288

dmaclach commented Dec 18, 2018

nguyenhuy commented Dec 18, 2018

maicki commented Dec 18, 2018

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mikezucc commented Dec 18, 2018

dmaclach commented Dec 18, 2018

Reduce startup time. #1288

Reduce startup time. #1288

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dmaclach commented Dec 18, 2018

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maicki commented Dec 18, 2018

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1. Run

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