203 - Removing lock in Scope to improve performance #322

dadhi · 2020-09-19T18:34:58Z

No description provided.

dzmitry-lahoda · 2020-09-19T19:04:43Z

src/DryIoc/ImTools.cs

@@ -3806,6 +3806,28 @@ public static ImMapEntry<V> GetEntryOrDefault<V>(this ImMap<V> map, int key)
            return entry != null && entry.Key == key ? entry : null;
        }

+        /// <summary>Looks for the sure present entry - in cases when we know for certain that the map contains the entry</summary>
+        [MethodImpl((MethodImplOptions)256)]
+        public static ImMapEntry<V> GetSurePresentEntry<V>(this ImMap<V> map, int key)


cool, if we know something is presented, than optimize!

Yes, my luck that I am in full control of the data structure.

dzmitry-lahoda · 2020-09-19T19:05:14Z

playground/Playground/RealisticUnitOfWorkBenchmark.cs

+|             Method |     Mean |     Error |    StdDev | Ratio | RatioSD |  Gen 0 | Gen 1 | Gen 2 | Allocated |
+|------------------- |---------:|----------:|----------:|------:|--------:|-------:|------:|------:|----------:|
+|               MsDI | 4.215 us | 0.0811 us | 0.0901 us |  1.00 |    0.00 | 1.0605 |     - |     - |   4.35 KB |
+|             DryIoc | 1.628 us | 0.0307 us | 0.0272 us |  0.39 |    0.01 | 0.7248 |     - |     - |   2.96 KB |


no so great :(

No, this is fine :) This is the comparison of just commenting lock vs complete solution, the original result for current v4.4.1 (with the lock) is higher in the same file.

The prev results:

| DryIoc | 1.868 us | 0.0226 us | 0.0200 us | 0.44 | 0.01 | 0.7248 | - | - | 2.96 KB | | DryIoc_MsDIAdapter | 2.651 us | 0.0404 us | 0.0338 us | 0.63 | 0.02 | 0.7286 | - | - | 2.98 KB |

dzmitry-lahoda · 2020-09-19T19:05:39Z

src/DryIoc/Container.cs

@@ -46,6 +46,9 @@ THE SOFTWARE.
 #if !PCL && !NET35 && !NET40 && !NET403
 #define SUPPORTS_DELEGATE_METHOD
 #endif
+#if !NET35 && !PCL


why not to drop net35 and pcl?

Dropping them in V5.
There is v5-dev branch where I did that allready. So the current fallback to lock will be removed in v5.

dzmitry-lahoda · 2020-09-19T19:08:11Z

src/DryIoc/Container.cs

+#if SUPPORTS_SPIN_WAIT
+                    var spinWait = new SpinWait();
+                    while (otherItemRef.Value == NoItem)
+                        spinWait.SpinOnce();


what if createValue failed? i mean there were 2 calls. first failed, than second will spin until third call will be done?

If it failed then the exception will stop everything anyway.

one thread said it will create value and factory delegate failed, the other thread was spinning, how that other will pass? lock, if locked delegate failed, allowed others to proceed.

The app will crash with all the threads, so it does not matter if one was spinned or not.

I am not sure what do you mean?

You mean the spinned thread will leak outside of the app? How?

what if do try catch of one thread, any chance second thread will loop forever?

dzmitry-lahoda · 2020-09-19T19:11:13Z

src/DryIoc/Container.cs

+                    while (otherItemRef.Value == NoItem)
+                        spinWait.SpinOnce();
+#else
+                    lock (itemRef) 


not sure about details of lock, never read it, but if lock is somethings have some averaging complex heuristics to spin until lock and this heuristics adds extra layers, but safes from CPU of spins in case of long locks, so it is good and safe on average. so removing it and replacing with custom heuristics in that spin is better in our case or write custom lock with different may be real time changed heuristics, but give results of benchmarks seems that is of not so big help? and more risks.

See my comment for benchmark, it is huge 10+ wing in the already highly optimized code.

And again, I almost never expect for the parallel code accessing the scope, so the majority of cases will never spin.
Also SpinWait has an adaptive implementation as well which will start yielding and thread sleeping after cirtain amount of iterations.

while (otherItemRef.Value == NoItem) spinWait.SpinOnce();

what is condition for while to stop? is any chance for infinite loop?

while (otherItemRef.Value == NoItem)

The condition will be met when createValue returns. If it does not return by hanging or throwing then we have the others problems to solve anyway.

I may add the timeout here but it will just add more non-determinizm and it kind of hard to decide on the value.

so yes, it was not about timeout, but about otherItemRef.Value changes it state to other to allow spin to pass, so all is ok.

lock (itemRef)

This is a copy-paste bug, it should be lock around otherItemRef.

dzmitry-lahoda · 2020-09-19T19:43:48Z

src/DryIoc/Container.cs

+#if SUPPORTS_SPIN_WAIT
+                    var spinWait = new SpinWait();
+                    while (otherItemRef.Value == NoItem)
+                        spinWait.SpinOnce();


one thread said it will create value and factory delegate failed, the other thread was spinning, how that other will pass? lock, if locked delegate failed, allowed others to proceed.

dzmitry-lahoda · 2020-09-19T19:45:47Z

other possible check - if other containers do the same.

dadhi · 2020-09-19T21:19:56Z

what if do try catch of one thread, any chance second thread will loop forever?

There is no possibility for it.
I am controlling how createValue is called and won't do the try-catch.
Assuming someone put the try-catch inside the createValue, then it still need to return something (including null) or re-throw. If it returns, then whatever value it is, it won't be NoItem. If it throws - app will crash, means we are good too.

The only possible hack is returning the NoItem by createValue, but this thing is internal and if you do the reflection hacking - then you deserve the problems :)

…h prev Autofac

…adBenchmarks and the BMs with prev Autofac

…Benchmarks and the BMs with prev Autofac

…zer with reuse

dadhi · 2020-10-11T12:11:42Z

I have replaced the locks everywhere and found one of the recursion issues in the process. It is now fixed

maximv added 3 commits September 17, 2020 23:15

removing locks

320c26f

replacing Thread.Sleep with Monitor.Wait / PulseAll

37cb13b

updating benchmark results

91d8131

dadhi changed the title ~~Fix for the issue - removing lock in Scope to improve performance~~ 203 - Removing lock in Scope to improve performance Sep 19, 2020

storing the current bm results to compare later

0c6d88c

dzmitry-lahoda reviewed Sep 19, 2020

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dzmitry-lahoda approved these changes Sep 19, 2020

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dadhi linked an issue Sep 20, 2020 that may be closed by this pull request

[Perf] Avoid locking of service creation in scope if possible #203

Closed

fixing the wrong the lock

3d807d2

dadhi mentioned this pull request Sep 27, 2020

Add ImMap.GetSurePresentValue method dadhi/ImTools#36

Closed

maximv and others added 5 commits October 2, 2020 12:02

factoring out the waiting code and the LoadBenchmarks and the BMs wit…

5c2a11d

…h prev Autofac

index on issue_203: 5c2a11d factoring out the waiting code and the Lo…

0a0dce0

…adBenchmarks and the BMs with prev Autofac

WIP on issue_203: 5c2a11d factoring out the waiting code and the Load…

7d13a35

…Benchmarks and the BMs with prev Autofac

fixes and refactorings; tests are passing; added new RegisterInitiali…

700164f

…zer with reuse

fixing the build

b1e2a89

dadhi merged commit de9f0a7 into master Oct 11, 2020

dadhi deleted the issue_203 branch April 2, 2021 06:33

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203 - Removing lock in Scope to improve performance #322

203 - Removing lock in Scope to improve performance #322

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203 - Removing lock in Scope to improve performance #322

203 - Removing lock in Scope to improve performance #322

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