GetAllGlobs optimizations

[cdmihai]

GetAllGlobs has become part of the VS solution load critical path. This PR does a couple of optimizations:

• makes MsBuildGlob computation lazy, so VS computes it on the first use, not when the solution opens
• reduces allocations

Numbers from GetAllGlobs when simulating the Roslyn.sln solution load:

Not including the lazy glob change:

Including the lazy glob change:

Closes #2647

[cdmihai]

This has some positive memory effect to normal evaluations as well.

Evaluation: Time (ms)

Test	Overall	Significant δ	Value
DotnetConsoleProject	✅	yes	90.5128 -> 89.9722 (-0.597%)
DotnetWebProject	🔴	yes	134.1791 -> 135.2581 (0.804%)
DotnetMvcProject	👌	no	159.2565 -> 159.4997 (0.153%)
Picasso	✅	yes	759.5962 -> 749.7776 (-1.293%)
SmallP2POldCsproj	✅	yes	131.4117 -> 128.2061 (-2.439%)
SmallP2PNewCsproj	✅	yes	240.465 -> 236.98 (-1.449%)
Generated_100_100_v150	✅	yes	1582.2244 -> 1558.1152 (-1.524%)
LargeP2POldCsproj	🔴	yes	2192.5697 -> 2245.8899 (2.432%)
roslyn	👌	no	9367.4792 -> 9422.6194 (0.589%)

Evaluation: Memory (bytes)

Test	Overall	Significant δ	Value
DotnetConsoleProject	✅	yes	4893316 -> 4860702 (-0.667%)
DotnetWebProject	✅	yes	6566869 -> 6533440 (-0.509%)
DotnetMvcProject	✅	yes	7409405 -> 7378798 (-0.413%)
Picasso	✅	yes	34226829 -> 33165484 (-3.101%)
SmallP2POldCsproj	✅	yes	5881835 -> 5800067 (-1.39%)
SmallP2PNewCsproj	✅	yes	10340682 -> 10217682 (-1.189%)
Generated_100_100_v150	✅	yes	143419601 -> 138482239 (-3.443%)
LargeP2POldCsproj	✅	yes	83705415 -> 81511535 (-2.621%)
roslyn	✅	yes	403004965 -> 386487561 (-4.099%)

Build: Time (ms)

Test	Overall	Significant δ	Value
DotnetConsoleProject	👌	no	23.0976 -> 23.1529 (0.239%)
DotnetWebProject	::ok_hand:	no	28.3275 -> 28.3214 (-0.022%)
DotnetMvcProject	🔴	yes	31.3032 -> 31.5834 (0.895%)
Picasso	✅	yes	3129.9459 -> 3071.3088 (-1.873%)
SmallP2POldCsproj	✅	yes	151.2811 -> 148.7585 (-1.667%)
SmallP2PNewCsproj	✅	yes	157.7064 -> 156.9531 (-0.478%)

Build: Memory (bytes)

Test	Overall	Significant δ	Value
DotnetConsoleProject	👌	no	1161445 -> 1161768 (0.028%)
DotnetWebProject	🔴	yes	1281363 -> 1284197 (0.221%)
DotnetMvcProject	🔴	yes	1458619 -> 1459441 (0.056%)
Picasso	✅	yes	121891367 -> 118498284 (-2.784%)
SmallP2POldCsproj	✅	yes	6149767 -> 6115086 (-0.564%)
SmallP2PNewCsproj	✅	yes	6414870 -> 6375686 (-0.611%)

[davkean]

This could be created multiple times is that a problem?

[cdmihai]

Thought about that as well, but after looking at how it's called, it should be single threaded. Evaluation and Project apis are single threaded. Then even if they were multi threaded, the Itemspecs themselves would be thread local. If however, in the future, the itemspecs end up getting shared between threads then yes, this will be a problem.

Do you think it's worth prematurely making it thread safe again?

[davkean]

No, just wanted to make sure it was deliberate.