[release/8.0-staging] Use a sorted module order for metadata generation #96168
Conversation
The reflection metadata generation within the compiler follows a simple algorithm: foreach module in compilation, for each type in the module, if the type generates metadata, generate metadata for it. But it turns out the list of modules that we start with is not sorted. This is not a problem for multithreaded stability, because none of this happens in the multithreaded phase, but it is a problem for delta patching - small change in a program can perturb the metadata blob for no good reason. This sorts the list.
ghost
added
the
|
Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas Issue DetailsBackport of #96007 to release/8.0-staging Customer ImpactTestingRiskIMPORTANT: If this backport is for a servicing release, please verify that:
|
jeffschwMSFT
left a comment
jeffschwMSFT
left a comment
There was a problem hiding this comment.
approved. we will take for consideration in 8.0.x
MichalStrehovsky
added
the
Servicing-consider
rbhanda
added
Servicing-approved
|
@MichalStrehovsky Friendly reminder that Tuesday January 16th 4pm is the Code Complete deadline for the February Release. If all requirements are met, please merge your PR before that date and time to ensure this fix gets included in that Release. |
Backport of #96007 to release/8.0-staging
/cc @MichalStrehovsky
Customer Impact
This fixes similar issue to #96167 so copying motivation from there:
Since native AOT compiler is multithreaded but we need deterministic outputs, we achieve the determinism by sorting the output before writing it to disk. The sorting ensures the same input produces the same output. However to support some first party patching scenarios, we would ideally also ensure "mostly the same input" produces "mostly the same output".
However, we didn't sort the assemblies before generating reflection metadata. This is a latent issue when it comes to reproducible builds - sorting is not needed if the set of compiled methods/types is identical. It is needed if the set varies.
Testing
Manual testing using the delta patching tool saw ~10x decrease in patch size. (This was tested together with #96167 although the impact of this one is a bit smaller.)
Risk
Low, we already use SortedSet for many other things.
IMPORTANT: If this backport is for a servicing release, please verify that:
The PR target branch is
release/X.0-staging, notrelease/X.0.If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.