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Commit 5a3d0c6e authored by Narayan Kamath's avatar Narayan Kamath
Browse files

Allow lazy preloading of zygote resources. 

Add a flag that controls resource preloading. If set, the zygote waits
until the first fork request to preload resources.

When applied to the secondary zygote, this approach appears to save
between 500-800ms of boot time once the webview RELRO step that uses
the 32 bit zygote is deferred.

Test: Manual
Bug: 32735001

Change-Id: Id387b7132d052fa51b9c25f0142fcd546b99662d
parent 95f50d73

core/java/com/android/internal/os/ZygoteConnection.java

+2 −0
Original line number Diff line number Diff line
@@ -171,6 +171,8 @@ class ZygoteConnection { 
                return handleAbiListQuery();

            }



            ZygoteInit.maybePreload();



            if (parsedArgs.preloadPackage != null) {

                return handlePreloadPackage(parsedArgs.preloadPackage,

                        parsedArgs.preloadPackageLibs);

core/java/com/android/internal/os/ZygoteInit.java

+25 −7
Original line number Diff line number Diff line
@@ -112,6 +112,8 @@ public class ZygoteInit { 
    private static final int ROOT_UID = 0;

    private static final int ROOT_GID = 0;



    private static boolean sPreloadComplete;



    static void preload(BootTimingsTraceLog bootTimingsTraceLog) {

        Log.d(TAG, "begin preload");

        bootTimingsTraceLog.traceBegin("BeginIcuCachePinning");
@@ -134,6 +136,15 @@ public class ZygoteInit { 
        endIcuCachePinning();

        warmUpJcaProviders();

        Log.d(TAG, "end preload");



        sPreloadComplete = true;

    }



    public static void maybePreload() {

        if (!sPreloadComplete) {

            Log.i(TAG, "Lazily preloading resources.");

            preload(new BootTimingsTraceLog("ZygoteInitTiming_lazy", Trace.TRACE_TAG_DALVIK));

        }

    }



    private static void beginIcuCachePinning() {
@@ -660,9 +671,12 @@ public class ZygoteInit { 
            boolean startSystemServer = false;

            String socketName = "zygote";

            String abiList = null;

            boolean enableLazyPreload = false;

            for (int i = 1; i < argv.length; i++) {

                if ("start-system-server".equals(argv[i])) {

                    startSystemServer = true;

                } else if ("--enable-lazy-preload".equals(argv[i])) {

                    enableLazyPreload = true;

                } else if (argv[i].startsWith(ABI_LIST_ARG)) {

                    abiList = argv[i].substring(ABI_LIST_ARG.length());

                } else if (argv[i].startsWith(SOCKET_NAME_ARG)) {
@@ -677,6 +691,9 @@ public class ZygoteInit { 
            }



            zygoteServer.registerServerSocket(socketName);

            // In some configurations, we avoid preloading resources and classes eagerly.

            // In such cases, we will preload things prior to our first fork.

            if (!enableLazyPreload) {

                bootTimingsTraceLog.traceBegin("ZygotePreload");

                EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_START,

                    SystemClock.uptimeMillis());
@@ -684,6 +701,7 @@ public class ZygoteInit { 
                EventLog.writeEvent(LOG_BOOT_PROGRESS_PRELOAD_END,

                    SystemClock.uptimeMillis());

                bootTimingsTraceLog.traceEnd(); // ZygotePreload

            }



            // Finish profiling the zygote initialization.

            SamplingProfilerIntegration.writeZygoteSnapshot();