Construct default MimeMap lazily rather than eagerly.
A side effect of CL topic r.android.com/q/topic:bug136256059_attempt2
was that the default MimeMap instance is now loaded eagerly (pre-fork)
regardless of whether any app process ends up using it, whereas
previously it was loaded lazily (post-fork) the first time an app
process used it.
This traded off CPU and memory use post-fork vs. pre-fork. Because it
isn't known / hasn't been proven whether and how many app processes
use that instance, the net CPU and memory impact is not known: if at
least one process makes use of a relevant API, the net impact will be
neutral or positive, or else negative.
Until this can be investigated and undergo system health review, this
CL topic changes the behavior back to post-fork lazy loading of the
default MimeMap instance.
Bug: 142019040
Test: Treehugger
Change-Id: I2a3f244240c51e7ada1f41a8abadb946ebcab40b
diff --git a/core/java/com/android/internal/os/RuntimeInit.java b/core/java/com/android/internal/os/RuntimeInit.java
index 103c79d..fd3cd42 100644
--- a/core/java/com/android/internal/os/RuntimeInit.java
+++ b/core/java/com/android/internal/os/RuntimeInit.java
@@ -203,13 +203,15 @@
public static void preForkInit() {
if (DEBUG) Slog.d(TAG, "Entered preForkInit.");
RuntimeInit.enableDdms();
+ // TODO(b/142019040#comment13): Decide whether to load the default instance eagerly, i.e.
+ // MimeMap.setDefault(DefaultMimeMapFactory.create());
/*
* Replace libcore's minimal default mapping between MIME types and file
* extensions with a mapping that's suitable for Android. Android's mapping
* contains many more entries that are derived from IANA registrations but
* with several customizations (extensions, overrides).
*/
- MimeMap.setDefault(DefaultMimeMapFactory.create());
+ MimeMap.setDefaultSupplier(DefaultMimeMapFactory::create);
}
@UnsupportedAppUsage
