[net6] Don't blindly load Mono components #6507
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grendello
requested review from
dellis1972,
jonathanpeppers and
jonpryor
as code owners
Whenever a NET6 Xamarin.Android app starts, MonoVM will probe for a
number of Mono components:
11-16 14:23:24.805 10791 10791 I monodroid-assembly: Trying to load shared library '/data/app/~~5lwn5C40pkRva2-L4kilZA==/com.microsoft.net6.helloandroid-MrYUTOqX7yZPkmtLOPnuuw==/split_config.arm64_v8a.apk!/lib/arm64-v8a/libmono-component-debugger.so'
11-16 14:23:24.806 10791 10791 I monodroid-assembly: Failed to load shared library '/data/app/~~5lwn5C40pkRva2-L4kilZA==/com.microsoft.net6.helloandroid-MrYUTOqX7yZPkmtLOPnuuw==/split_config.arm64_v8a.apk!/lib/arm64-v8a/libmono-component-debugger.so'.
dlopen failed: library "/data/app/~~5lwn5C40pkRva2-L4kilZA==/com.microsoft.net6.helloandroid-MrYUTOqX7yZPkmtLOPnuuw==/split_config.arm64_v8a.apk!/lib/arm64-v8a/libmono-component-debugger.so" not found
The above is repeated for, currently, 3 components. Together, the
failed load attempts cost us around 1ms of startup time (on Pixel 3 XL,
the amount of time will depend on the speed of device's storage and CPU)
Since we know at the build time which components are included, we can
optimize the startup process by recording a flag indicating which
components can be loaded successfully.
Add a `mono_components_mask` field to `ApplicationConfig` which is set
to a bitmask indicating which components are packaged. On application
startup, whenever `monodroid_dlopen` is called, we has the name of the
library passed to us by Mono and see if it matches one of the known
hashes for the various components. If yes, we consult the mask stored
at build time and attempt to load the component only if its bit is set.
The above check is performed **only** during application startup since
that's when Mono probes for the components and it would be a waste of
time later in the application life.
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jonathanpeppers
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Nov 19, 2021
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The MSBuild changes LGTM 👍
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Whenever a NET6 Xamarin.Android app starts, MonoVM will probe for a
number of Mono components:
The above is repeated for, currently, 3 components. Together, the
failed load attempts cost us around 1ms of startup time (on Pixel 3 XL,
the amount of time will depend on the speed of device's storage and CPU)
Since we know at the build time which components are included, we can
optimize the startup process by recording a flag indicating which
components can be loaded successfully.
Add a
mono_components_maskfield toApplicationConfigwhich is setto a bitmask indicating which components are packaged. On application
startup, whenever
monodroid_dlopenis called, we has the name of thelibrary passed to us by Mono and see if it matches one of the known
hashes for the various components. If yes, we consult the mask stored
at build time and attempt to load the component only if its bit is set.
The above check is performed only during application startup since
that's when Mono probes for the components and it would be a waste of
time later in the application life.