Go full Async

[benaadams]

Is currently blocking in some of the paths; making it fully async gives no significant drop off and the FileStream can then also be async.

AsyncFileWriterTester>dotnet run -c Release
100,000 bounded capacity.
Total Time: 1.9647976 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:02.3469906
------------------------

10,000 bounded capacity.
Total Time: 1.7327357 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:01.8846596
------------------------

1,000 bounded capacity.
Total Time: 1.7522801 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:02.2072572
------------------------

100 bounded capacity.
Total Time: 1.7023758 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:01.9285510
------------------------

Press ENTER to continue.

[benaadams]

And on Core 2.1 preview

AsyncFileWriterTester>dotnet run -c Release
100,000 bounded capacity.
Total Time: 1.8987974 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:01.7353395
------------------------

10,000 bounded capacity.
Total Time: 1.6465742 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:01.4772885
------------------------

1,000 bounded capacity.
Total Time: 1.6717849 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:01.6662691
------------------------

100 bounded capacity.
Total Time: 1.7220855 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:01.8154073
------------------------

Press ENTER to continue.

[electricessence]

https://www.reddit.com/r/dotnet/comments/8c4ova/ado_async_all_the_way_down_the_tubes/dxf80rw/?st=jg1dbwdr&sh=75405bf7

I'm reviewing the code now. Thanks for your submission.
Be sure to look at the test file to see that 1,000,000 rows have been written.

[benaadams]

I can rebase? There should hopefully be no slow down from the full async in this PR?

[benaadams]

Rebasing has hit the performance; looking it it

[benaadams]

There's something definitely wrong with FileStream in async mode...

Anyway, current - everything async other than FileStream

AsyncFileWriterTester>dotnet run -c Release
100,000 bounded capacity.
Total Time: 2.3680831 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:02.6254878
------------------------

10,000 bounded capacity.
Total Time: 2.0399536 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:02.3390593
------------------------

1,000 bounded capacity.
Total Time: 2.1499109 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:02.3699012
------------------------

100 bounded capacity.
Total Time: 2.0656293 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:03.0224013
------------------------

Press ENTER to continue.

Switch FileStream to async

AsyncFileWriterTester>dotnet run -c Release
100,000 bounded capacity.
Total Time: 4.1238278 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:14.3291113
------------------------

10,000 bounded capacity.
Total Time: 4.370184 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:19.3693952
------------------------

1,000 bounded capacity.
Total Time: 4.1362524 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:19.0104628
------------------------

100 bounded capacity.
Total Time: 4.2608508 seconds
Total Bytes: 115,888,890
Total Wait Time: 00:00:20.4615956
------------------------

Press ENTER to continue.

[benaadams]

Raised issue https://github.com/dotnet/corefx/issues/29129

[electricessence]

Let's do some more investigation first. @benaadams your async tests aren't exactly at parity with the synchronous ones.

[electricessence]

There's a stack overflow I've seen before about FileStream async. I'd search for that. There may not be anything wrong.

[electricessence]

After my refactor, here's the results I'm getting.
I strongly suggest trying to reimplement your ParallelAsync tests in AsyncTester.cs.

Synchronous tests have to remain as a benchmark.

TESTS WITH PARTIAL BLOCKING:

Synchronized file stream benchmark.
Total Time: 2.5686957 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 00:00:08.0020843
------------------------

100,000 bounded capacity.
Total Time: 1.8137859 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 00:00:03.1323739
------------------------

10,000 bounded capacity.
Total Time: 1.7435298 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 00:00:02.6384457
------------------------

1,000 bounded capacity.
Total Time: 2.4563794 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 00:00:08.4284548
------------------------

100 bounded capacity.
Total Time: 38.1694338 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 00:38:06.0996803
------------------------


FULLY ASYNCHRONOUS:

100,000 bounded capacity.
Total Time: 8.3645859 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 00:16:05.7421462
------------------------

10,000 bounded capacity.
Total Time: 19.7808654 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 00:58:04.0314021
------------------------

1,000 bounded capacity.
Total Time: 29.7159541 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 02:21:54.4839711
------------------------

100 bounded capacity.
Total Time: 121.6788821 seconds
Total Bytes: 115,888,890
Aggregate Waiting: 14:09:48.1087417
------------------------

[electricessence]

https://github.com/electricessence/AsyncFileWriter/blob/master/AsyncFileWriterTester/AsyncTester.cs#L61
I added an assertion to ensure the file bytes match. If you don't see a significant slow down in time using 100 bounded capacity, your test is probably not actually finishing.