different bookie trigger gcOverreplicatedLedger randomly

Author: fanjianye

bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/ScanAndCompareGarbageCollector.java

@@ -94,9 +94,10 @@ public ScanAndCompareGarbageCollector(LedgerManager ledgerManager, CompactableLe
         this.selfBookieAddress = BookieImpl.getBookieId(conf);
 
         this.gcOverReplicatedLedgerIntervalMillis = conf.getGcOverreplicatedLedgerWaitTimeMillis();
-        this.lastOverReplicatedLedgerGcTimeMillis = System.currentTimeMillis();
         if (gcOverReplicatedLedgerIntervalMillis > 0) {
             this.enableGcOverReplicatedLedger = true;
+            this.lastOverReplicatedLedgerGcTimeMillis = System.currentTimeMillis() +
+                    (long)(gcOverReplicatedLedgerIntervalMillis * Math.random());
         }
         this.maxConcurrentRequests = conf.getGcOverreplicatedLedgerMaxConcurrentRequests();
         LOG.info("Over Replicated Ledger Deletion : enabled={}, interval={}, maxConcurrentRequests={}",