Speed of synchronized

[Christian Köstlin via Digitalmars-d-learn]

On 17/10/16 14:44, Christian Köstlin wrote:
> On 17/10/16 14:09, Daniel Kozak via Digitalmars-d-learn wrote:
>> Dne 16.10.2016 v 10:41 Christian Köstlin via Digitalmars-d-learn napsal(a):
>>> Hi,
>>>
>>> for an exercise I had to implement a thread safe counter.
>>> This is what I came up with:
>>> ....
>>>
>>> btw. I run the code with dub run --build=release
>>>
>>> Thanks in advance,
>>> Christian
>> So I have done some testing, on my pc:
>> Java result
>> counter.AtomicLongCounter at 7ff5e7d8 expected: 2000000 got: 1000000 in: 83ms
>> counter.ThreadSafe2Counter at 59b44e4b expected: 2000000 got: 1000000 in: 77ms
>> counter.ThreadSafe1Counter at 2e5f6b4b expected: 2000000 got: 1000000 in:
>> 154ms
>> counter.ThreadUnsafeCounter at 762b155d expected: 2000000 got: 730428 in: 13ms
>>
>> and my D results (code: http://dpaste.com/3QFXACY ):
>> snip.AtomicCounter: got: 1000000 expected: 1000000 in 77 ms and 783 μs
>> snip.ThreadSafe1Counter: got: 1000000 expected: 1000000 in 287 ms, 727
>> μs, and 3 hnsecs
>> snip.ThreadSafe2Counter: got: 1000000 expected: 1000000 in 281 ms, 117
>> μs, and 1 hnsec
>> snip.ThreadSafe3Counter: got: 1000000 expected: 1000000 in 158 ms, 480
>> μs, and 2 hnsecs
>> snip.ThreadUnsafeCounter: got: 1000000 expected: 1000000 in 6 ms, 682
>> μs, and 1 hnsec
>>
>> so atomic is same as in Java pthread_mutex is same speed as java
>> synchronized
>> D mutexes and D synchronized are almost same, I belive that if I could
>> setup same attrs as in pthread version it will be around 160ms too.
>>
>> Unsafe is almost same for D and java. Only java ReentrantLock seems to
>> work better. I believe there is some trick, so it will end up not using
>> mutexes in the end at all. For example consider this change in D code:
>>
>> void doIt(alias counter)() {
>>   auto thg = new ThreadGroup();
>>   for (int i=0; i<NR_OF_THREADS; ++i) {
>>      thg.create(&threadFuncBody!(counter));
>>   }
>>   thg.joinAll();
>> }
>>
>> change it to
>>
>> void doIt(alias counter)() {
>>   auto thg = new ThreadGroup();
>>   for (int i=0; i<NR_OF_THREADS; ++i) {
>>     auto tc = thg.create(&threadFuncBody!(counter));
>>     tc.join();
>>   }
>> }
>>
>> and results are:
>>
>> snip.AtomicCounter: got: 1000000 expected: 1000000 in 22 ms, 251 μs, and
>> 6 hnsecs
>> snip.ThreadSafe1Counter: got: 1000000 expected: 1000000 in 46 ms, 146
>> μs, and 3 hnsecs
>> snip.ThreadSafe2Counter: got: 1000000 expected: 1000000 in 44 ms, 961
>> μs, and 5 hnsecs
>> snip.ThreadSafe3Counter: got: 1000000 expected: 1000000 in 42 ms, 512
>> μs, and 8 hnsecs
>> snip.ThreadUnsafeCounter: got: 1000000 expected: 1000000 in 2 ms, 108
>> μs, and 5 hnsecs
>>
>>
>>
>>
>>
> thank you for looking into it.
> this seems to be quite good.
> I did expect something in those lines, but got the mentioned numbers on
> my os x macbook. perhaps its a os x glitch.
> 
Thanks for the hint about the OS. I rerun the tests on a linux machine,
and there everything is fine!
linux dlang code:
app.AtomicCounter: got: 1000000 expected: 1000000 in 24 ms, 387 μs, and
3 hnsecs
app.ThreadSafe1Counter: got: 1000000 expected: 1000000 in 143 ms, 534
μs, and 9 hnsecs
app.ThreadSafe2Counter: got: 1000000 expected: 1000000 in 159 ms, 685
μs, and 1 hnsec
app.ThreadUnsafeCounter: got: 399937 expected: 1000000 in 9 ms and 556 μs
from example got: 156 ms, 198 μs, and 9 hnsecs


linux java code:
counter.CounterTest > testAtomicIntCounter STANDARD_OUT
    counter.AtomicIntCounter at 1f2a2347 expected: 1000000 got: 1000000 in:
29ms

counter.CounterTest > testAtomicLongCounter STANDARD_OUT
    counter.AtomicLongCounter at 675ad891 expected: 1000000 got: 1000000
in: 24ms

counter.CounterTest > testThreadSafe2Counter STANDARD_OUT
    counter.ThreadSafe2Counter at 3043c6d2 expected: 1000000 got: 1000000
in: 38ms

counter.CounterTest > testThreadSafeCounter STANDARD_OUT
    counter.ThreadSafe1Counter at bac4ba3 expected: 1000000 got: 1000000
in: 145ms

counter.CounterTest > testThreadUnsafeCounter STANDARD_OUT
    counter.ThreadUnsafeCounter at 2fe82bf8 expected: 1000000 got: 433730
in: 9ms


Could someone check the numbers on another OS-X machine? Unfortunately I
only have one available.

Thanks in advance!