Merge "ActivityManager: don't freeze processes holding file locks" (9b2cce77) · Commits · e / os / android_frameworks_base

core/java/android/os/Process.java

+37 −0

Original line number	Diff line number	Diff line
		@@ -31,9 +31,12 @@ import dalvik.system.VMRuntime;

		import libcore.io.IoUtils;

		import java.io.BufferedReader;
		import java.io.FileDescriptor;
		import java.io.FileReader;
		import java.io.IOException;
		import java.util.Map;
		import java.util.StringTokenizer;
		import java.util.concurrent.TimeoutException;

		/**
		@@ -1430,4 +1433,38 @@ public class Process {
		}

		private static native int nativePidFdOpen(int pid, int flags) throws ErrnoException;

		/**
		* Checks if a process corresponding to a specific pid owns any file locks.
		* @param pid The process ID for which we want to know the existence of file locks.
		* @return true If the process holds any file locks, false otherwise.
		* @throws IOException if /proc/locks can't be accessed.
		*
		* @hide
		*/
		public static boolean hasFileLocks(int pid) throws IOException {
		BufferedReader br = null;

		try {
		br = new BufferedReader(new FileReader("/proc/locks"));
		String line;

		while ((line = br.readLine()) != null) {
		StringTokenizer st = new StringTokenizer(line);

		for (int i = 0; i < 5 && st.hasMoreTokens(); i++) {
		String str = st.nextToken();
		if (i == 4 && Integer.parseInt(str) == pid) {
		return true;
		}
		}
		}

		return false;
		} finally {
		if (br != null) {
		br.close();
		}
		}
		}
		}

+57 −25

Original line number	Diff line number	Diff line
		@@ -1101,15 +1101,26 @@ public final class CachedAppOptimizer {
		}

		private void freezeProcess(ProcessRecord proc) {
		final int pid;
		final String name;
		final int pid = proc.pid;
		final String name = proc.processName;
		final long unfrozenDuration;
		final boolean frozen;

		synchronized (mAm) {
		pid = proc.pid;
		name = proc.processName;
		try {
		// pre-check for locks to avoid unnecessary freeze/unfreeze operations
		if (Process.hasFileLocks(pid)) {
		if (DEBUG_FREEZER) {
		Slog.d(TAG_AM, name + " (" + pid + ") holds file locks, not freezing");
		}
		return;
		}
		} catch (IOException e) {
		Slog.e(TAG_AM, "Not freezing. Unable to check file locks for " + name + "(" + pid
		+ "): " + e);
		return;
		}

		synchronized (mAm) {
		if (proc.curAdj < ProcessList.CACHED_APP_MIN_ADJ
		\|\| proc.shouldNotFreeze) {
		if (DEBUG_FREEZER) {
		@@ -1141,7 +1152,11 @@ public final class CachedAppOptimizer {
		frozen = proc.frozen;
		}

		if (frozen) {
		if (!frozen) {
		return;
		}


		if (DEBUG_FREEZER) {
		Slog.d(TAG_AM, "froze " + pid + " " + name);
		}
		@@ -1165,6 +1180,23 @@ public final class CachedAppOptimizer {
		name,
		unfrozenDuration);
		}

		try {
		// post-check to prevent races
		if (Process.hasFileLocks(pid)) {
		if (DEBUG_FREEZER) {
		Slog.d(TAG_AM, name + " (" + pid + ") holds file locks, reverting freeze");
		}

		synchronized (mAm) {
		unfreezeAppLocked(proc);
		}
		}
		} catch (IOException e) {
		Slog.e(TAG_AM, "Unable to check file locks for " + name + "(" + pid + "): " + e);
		synchronized (mAm) {
		unfreezeAppLocked(proc);
		}
		}
		}