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Commit 9a88f10b authored by Mathieu Chartier's avatar Mathieu Chartier
Browse files

Remove unnecessary explicit GC in ZygoteInit. 

Removes > 1s of GC time and hundreds of GC during device boot.

Zygote size before: 8388608
Zygote size after: 8388608

No increase in zygote space size due to zygote compaction.

Bug: 16398684

Change-Id: I3c6f5a0b26a207ab39bb0a952400d7488e42f00c
parent 42895561

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

+2 −66
Original line number Diff line number Diff line
@@ -86,12 +86,6 @@ public class ZygoteInit { 
     */

    private static Resources mResources;



    /**

     * The number of times that the main Zygote loop

     * should run before calling gc() again.

     */

    static final int GC_LOOP_COUNT = 10;



    /**

     * The name of a resource file that contains classes to preload.

     */
@@ -286,11 +280,6 @@ public class ZygoteInit { 
            float defaultUtilization = runtime.getTargetHeapUtilization();

            runtime.setTargetHeapUtilization(0.8f);



            // Start with a clean slate.

            System.gc();

            runtime.runFinalizationSync();

            Debug.startAllocCounting();



            try {

                BufferedReader br

                    = new BufferedReader(new InputStreamReader(is), 256);
@@ -309,15 +298,6 @@ public class ZygoteInit { 
                            Log.v(TAG, "Preloading " + line + "...");

                        }

                        Class.forName(line);

                        if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) {

                            if (false) {

                                Log.v(TAG,

                                    " GC at " + Debug.getGlobalAllocSize());

                            }

                            System.gc();

                            runtime.runFinalizationSync();

                            Debug.resetGlobalAllocSize();

                        }

                        count++;

                    } catch (ClassNotFoundException e) {

                        Log.w(TAG, "Class not found for preloading: " + line);
@@ -347,8 +327,6 @@ public class ZygoteInit { 
                // Fill in dex caches with classes, fields, and methods brought in by preloading.

                runtime.preloadDexCaches();



                Debug.stopAllocCounting();



                // Bring back root. We'll need it later.

                setEffectiveUser(ROOT_UID);

                setEffectiveGroup(ROOT_GID);
@@ -366,10 +344,7 @@ public class ZygoteInit { 
    private static void preloadResources() {

        final VMRuntime runtime = VMRuntime.getRuntime();



        Debug.startAllocCounting();

        try {

            System.gc();

            runtime.runFinalizationSync();

            mResources = Resources.getSystem();

            mResources.startPreloading();

            if (PRELOAD_RESOURCES) {
@@ -394,22 +369,12 @@ public class ZygoteInit { 
            mResources.finishPreloading();

        } catch (RuntimeException e) {

            Log.w(TAG, "Failure preloading resources", e);

        } finally {

            Debug.stopAllocCounting();

        }

    }



    private static int preloadColorStateLists(VMRuntime runtime, TypedArray ar) {

        int N = ar.length();

        for (int i=0; i<N; i++) {

            if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) {

                if (false) {

                    Log.v(TAG, " GC at " + Debug.getGlobalAllocSize());

                }

                System.gc();

                runtime.runFinalizationSync();

                Debug.resetGlobalAllocSize();

            }

            int id = ar.getResourceId(i, 0);

            if (false) {

                Log.v(TAG, "Preloading resource #" + Integer.toHexString(id));
@@ -430,14 +395,6 @@ public class ZygoteInit { 
    private static int preloadDrawables(VMRuntime runtime, TypedArray ar) {

        int N = ar.length();

        for (int i=0; i<N; i++) {

            if (Debug.getGlobalAllocSize() > PRELOAD_GC_THRESHOLD) {

                if (false) {

                    Log.v(TAG, " GC at " + Debug.getGlobalAllocSize());

                }

                System.gc();

                runtime.runFinalizationSync();

                Debug.resetGlobalAllocSize();

            }

            int id = ar.getResourceId(i, 0);

            if (false) {

                Log.v(TAG, "Preloading resource #" + Integer.toHexString(id));
@@ -459,7 +416,7 @@ public class ZygoteInit { 
     * softly- and final-reachable objects, along with any other garbage.

     * This is only useful just before a fork().

     */

    /*package*/ static void gc() {

    /*package*/ static void gcAndFinalize() {

        final VMRuntime runtime = VMRuntime.getRuntime();



        /* runFinalizationSync() lets finalizers be called in Zygote,
@@ -468,9 +425,6 @@ public class ZygoteInit { 
        System.gc();

        runtime.runFinalizationSync();

        System.gc();

        runtime.runFinalizationSync();

        System.gc();

        runtime.runFinalizationSync();

    }



    /**
@@ -613,7 +567,7 @@ public class ZygoteInit { 
            SamplingProfilerIntegration.writeZygoteSnapshot();



            // Do an initial gc to clean up after startup

            gc();

            gcAndFinalize();



            // Disable tracing so that forked processes do not inherit stale tracing tags from

            // Zygote.
@@ -682,27 +636,9 @@ public class ZygoteInit { 
        fds.add(sServerSocket.getFileDescriptor());

        peers.add(null);



        int loopCount = GC_LOOP_COUNT;

        while (true) {

            int index;



            /*

             * Call gc() before we block in select().

             * It's work that has to be done anyway, and it's better

             * to avoid making every child do it.  It will also

             * madvise() any free memory as a side-effect.

             *

             * Don't call it every time, because walking the entire

             * heap is a lot of overhead to free a few hundred bytes.

             */

            if (loopCount <= 0) {

                gc();

                loopCount = GC_LOOP_COUNT;

            } else {

                loopCount--;

            }





            try {

                fdArray = fds.toArray(fdArray);

                index = selectReadable(fdArray);