From c1c49c024f990bf54b2a7d16fdf5110263693aea Mon Sep 17 00:00:00 2001 From: Dan Egnor Date: Fri, 30 Oct 2009 17:35:39 -0700 Subject: Use setRepeating() rather than setInexactRepeating() for backup scheduling, and add some random fuzz to the scheduling times, to make sure we aren't creating hour-aligned server load spikes. See bug 2226553 for details & Dr. No information. --- .../java/com/android/server/BackupManagerService.java | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/services/java/com/android/server/BackupManagerService.java b/services/java/com/android/server/BackupManagerService.java index 82a7c1c6d90e..754e6e578b53 100644 --- a/services/java/com/android/server/BackupManagerService.java +++ b/services/java/com/android/server/BackupManagerService.java @@ -76,6 +76,7 @@ import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; +import java.util.Random; class BackupManagerService extends IBackupManager.Stub { private static final String TAG = "BackupManagerService"; @@ -85,6 +86,9 @@ class BackupManagerService extends IBackupManager.Stub { // trigger an immediate pass. private static final long BACKUP_INTERVAL = AlarmManager.INTERVAL_HOUR; + // Random variation in backup scheduling time to avoid server load spikes + private static final int FUZZ_MILLIS = 5 * 60 * 1000; + // The amount of time between the initial provisioning of the device and // the first backup pass. private static final long FIRST_BACKUP_INTERVAL = 12 * AlarmManager.INTERVAL_HOUR; @@ -1949,9 +1953,15 @@ class BackupManagerService extends IBackupManager.Stub { } private void startBackupAlarmsLocked(long delayBeforeFirstBackup) { - long when = System.currentTimeMillis() + delayBeforeFirstBackup; - mAlarmManager.setInexactRepeating(AlarmManager.RTC_WAKEUP, when, - BACKUP_INTERVAL, mRunBackupIntent); + // We used to use setInexactRepeating(), but that may be linked to + // backups running at :00 more often than not, creating load spikes. + // Schedule at an exact time for now, and also add a bit of "fuzz". + + Random random = new Random(); + long when = System.currentTimeMillis() + delayBeforeFirstBackup + + random.nextInt(FUZZ_MILLIS); + mAlarmManager.setRepeating(AlarmManager.RTC_WAKEUP, when, + BACKUP_INTERVAL + random.nextInt(FUZZ_MILLIS), mRunBackupIntent); mNextBackupPass = when; } -- cgit v1.2.3-59-g8ed1b