increase default sync period, and wait for last sync to finish before submitting another. patch by jbellis; reviewed by Brandon Williams for CASSANDRA-668

git-svn-id: https://svn.apache.org/repos/asf/incubator/cassandra/branches/cassandra-0.5@896139 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -5,6 +5,8 @@
    giving the false indication they were being used. (CASSANDRA-651)
  * Avoid redundant write of the same mutation. (CASSANDRA-662)
  * Abort bootstrap if IP is already in the token ring (CASSANDRA-663)
+ * increase default commitlog sync period, and wait for last sync to 
+   finish before submitting another (CASSANDRA-668)
 
 
 0.5.0 RC1

conf/storage-conf.xml

@@ -304,11 +304,10 @@
   <CommitLogSync>periodic</CommitLogSync>
   <!--
    ~ Interval at which to perform syncs of the CommitLog in periodic mode.
-   ~ Usually the default of 1000ms is fine; increase it only if the
-   ~ CommitLog PendingTasks backlog in jmx shows that you are frequently
-   ~ scheduling a second sync while the first has not yet been processed.
+   ~ Usually the default of 10000ms is fine; increase it if your i/o
+   ~ load is such that syncs are taking excessively long times.
   -->
-  <CommitLogSyncPeriodInMS>1000</CommitLogSyncPeriodInMS>
+  <CommitLogSyncPeriodInMS>10000</CommitLogSyncPeriodInMS>
   <!--
    ~ Delay (in milliseconds) during which additional commit log entries
    ~ may be written before fsync in batch mode.  This will increase

src/java/org/apache/cassandra/db/CommitLog.java

@@ -209,15 +209,19 @@ public class CommitLog
                 {
                     while (true)
                     {
-                        executor.submit(syncer);
                         try
                         {
+                            executor.submit(syncer).get();
                             Thread.sleep(DatabaseDescriptor.getCommitLogSyncPeriod());
                         }
                         catch (InterruptedException e)
                         {
                             throw new RuntimeException(e);
                         }
+                        catch (ExecutionException e)
+                        {
+                            throw new RuntimeException(e);
+                        }
                     }
                 }
             }, "PERIODIC-COMMIT-LOG-SYNCER").start();