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Avoid x-targeting perf impact on vcxproj #1278

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merged 1 commit into from
Oct 28, 2016
Merged

Avoid x-targeting perf impact on vcxproj #1278

merged 1 commit into from
Oct 28, 2016

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rainersigwald
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Targeted mitigation for #1276.

VC++ noticed a dramatic regression in solution-load performance related to
the time cost of ResolveProjectReferences. That affects all projects, but
we can safely assume that a .vcxproj is NOT using cross-targeting, while
it's impossible to detect from the outside whether a .csproj is.

This commit avoids the regression for C++ projects by just not calling the
MSBuild task again for .vcxproj references.

/cc @nguerrera @olgaark @srivatsn

@rainersigwald rainersigwald added this to the Visual Studio 15 RC milestone Oct 27, 2016
@nguerrera
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nguerrera commented Oct 27, 2016 •
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Was about to say looks good then saw the error is related to your change:

error MSB4116: The condition "'%(_MSBuildProjectReferenceExistent.Extension)' != '.vcxproj'" 
on the "_GetProjectReferenceTargetFrameworkProperties" target has a reference to item 
metadata. References to item metadata are not allowed in target conditions unless they
are part of an item transform.

@rainersigwald
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Someday I will either internalize that restriction or remove it! Looking.

@rainersigwald
Avoid x-targeting perf impact on vcxproj
36a8c7f 
Targeted mitigation for dotnet#1276.

VC++ noticed a dramatic regression in solution-load performance related to
the time cost of ResolveProjectReferences. That affects all projects, but
we can safely assume that a .vcxproj is NOT using cross-targeting, while
it's impossible to detect from the outside whether a .csproj is.

This commit avoids the regression for C++ projects by just not calling the
MSBuild task again for .vcxproj references.
@rainersigwald rainersigwald reopened this Oct 27, 2016
@olgaark
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olgaark commented Oct 28, 2016

Looks good to me too. Thanks!

From: Nick Guerrera [mailto:[email protected]]
Sent: Thursday, October 27, 2016 4:47 PM
To: Microsoft/msbuild [email protected]
Cc: Olga Arkhipova [email protected]; Mention [email protected]
Subject: Re: [Microsoft/msbuild] Avoid x-targeting perf impact on vcxproj (#1278)

@nguerrera approved this pull request.

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I am confirming that a) this doesn't break cross-targeting for .csproj, and b) it does reduce time for .vcxproj.

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Validated:

  • Significant reduction in _PerfIntellisenseInfo execution time on the customer project (.vcxproj)
  • Cross-targeting solution from @nguerrera returns a netstandard1.3 assembly when called from a .NET 4.6 project, and netstandard1.1 when called from a .NET 4.5 project.

@rainersigwald rainersigwald merged commit b6ff43b into dotnet:master Oct 28, 2016
@rainersigwald rainersigwald deleted the vcxproj-avoid-negotiation branch October 28, 2016 18:47
rainersigwald added a commit to rainersigwald/msbuild that referenced this pull request Mar 15, 2017
@rainersigwald
Ask ProjectReferences if they cross-target
69a3a3e 
Before cross-targeting was implemented, a project had a single output
that was queried in ResolveProjectReferences by either `GetTargetPath`
(in single-project-build scenarios) or the default target (`Build`) in
command line builds.

A cross-targeting project doesn't have a single output--it has one for
each of its `TargetFrameworks`. A ProjectReference, then, has to first
figure out which output to ask for--the one that's the best fit for the
current project.

The initial implementation of this was simple: unconditionally call
`GetTargetFrameworkProperties` on every ProjectReference, passing a
`ReferringTargetFramework`. Then, if the project cross-targets, specify
the resulting TF on future calls to the ProjectReference. If the project
has a single TF, do not specify it to avoid building it once (from the
solution  build) and again (from a reference, explicitly specifying the
one TF).

Unfortunately, adding a global property for `ReferringTargetFramework`
will result in a separate evaluation for the project. This means that
almost _every_ project in a solution will be evaluated at least
twice--once directly, with no special global properties, and once for
each unique `ReferringTargetFramework` that refers to it. This can be
particularly onerous for C++ projects (.vcxproj), where evaluation time
is nontrivial and doubling it is noticeable. That was mitigated by
special-casing vcxproj in dotnet#1278, but that is inelegant and doesn't
address the root cause.

This change alters the calling pattern for `ProjectReference`s. Instead
of asking all references for the correct TF, it breaks the problem into
multiple phases:

* Ask all references whether they cross-target, and split into
cross-targeting and non-cross-targeting lists.
* Perform the `GetTargetFrameworkProperties` query only on projects that
reported that they cross-targeted.
* Update (in place) the existing `_MSBuildProjectReferenceExistent` item
to pass or undefine the relevant properties based on whether the
reference cross-targets (and what TF is the best match).

Fixes dotnet#1276.
@rainersigwald rainersigwald mentioned this pull request Mar 15, 2017
Closed
rainersigwald added a commit to rainersigwald/msbuild that referenced this pull request Aug 4, 2017
@rainersigwald
Ask ProjectReferences if they cross-target
4b6c96a 
Before cross-targeting was implemented, a project had a single output
that was queried in ResolveProjectReferences by either `GetTargetPath`
(in single-project-build scenarios) or the default target (`Build`) in
command line builds.

A cross-targeting project doesn't have a single output--it has one for
each of its `TargetFrameworks`. A ProjectReference, then, has to first
figure out which output to ask for--the one that's the best fit for the
current project.

The initial implementation of this was simple: unconditionally call
`GetTargetFrameworkProperties` on every ProjectReference, passing a
`ReferringTargetFramework`. Then, if the project cross-targets, specify
the resulting TF on future calls to the ProjectReference. If the project
has a single TF, do not specify it to avoid building it once (from the
solution  build) and again (from a reference, explicitly specifying the
one TF).

Unfortunately, adding a global property for `ReferringTargetFramework`
will result in a separate evaluation for the project. This means that
almost _every_ project in a solution will be evaluated at least
twice--once directly, with no special global properties, and once for
each unique `ReferringTargetFramework` that refers to it. This can be
particularly onerous for C++ projects (.vcxproj), where evaluation time
is nontrivial and doubling it is noticeable. That was mitigated by
special-casing vcxproj in dotnet#1278, but that is inelegant and doesn't
address the root cause.

This change alters the calling pattern for `ProjectReference`s. Instead
of asking all references for the correct TF, it breaks the problem into
multiple phases:

* Ask all references whether they cross-target, and split into
cross-targeting and non-cross-targeting lists.
* Perform the `GetTargetFrameworkProperties` query only on projects that
reported that they cross-targeted.
* Update (in place) the existing `_MSBuildProjectReferenceExistent` item
to pass or undefine the relevant properties based on whether the
reference cross-targets (and what TF is the best match).

Fixes dotnet#1276.
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@rainersigwald @nguerrera @olgaark @dnfclas @Sarabeth-Jaffe-Microsoft