svn commit: r1185409 - in /hbase/branches/0.92: CHANGES.txt src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java

[la...@apache.org]

Author: larsh
Date: Mon Oct 17 22:34:05 2011
New Revision: 1185409

URL: http://svn.apache.org/viewvc?rev=1185409&view=rev
Log:
HBASE-4562  When split doing offlineParentInMeta encounters error, it'll cause data loss

Modified:
    hbase/branches/0.92/CHANGES.txt
    hbase/branches/0.92/src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java

Modified: hbase/branches/0.92/CHANGES.txt
URL: http://svn.apache.org/viewvc/hbase/branches/0.92/CHANGES.txt?rev=1185409&r1=1185408&r2=1185409&view=diff
==============================================================================
--- hbase/branches/0.92/CHANGES.txt (original)
+++ hbase/branches/0.92/CHANGES.txt Mon Oct 17 22:34:05 2011
@@ -713,6 +713,8 @@ Release 0.90.5 - Unreleased
    HBASE-4570. Fix a race condition that could cause inconsistent results
                from scans during concurrent writes. (todd and Jonathan Jsieh
                via todd)
+   HBASE-4562  When split doing offlineParentInMeta encounters error, it'll
+               cause data loss (bluedavy via Lars H)
 
   IMPROVEMENT
    HBASE-4205  Enhance HTable javadoc (Eric Charles)

Modified: hbase/branches/0.92/src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java
URL: http://svn.apache.org/viewvc/hbase/branches/0.92/src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java?rev=1185409&r1=1185408&r2=1185409&view=diff
==============================================================================
--- hbase/branches/0.92/src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java (original)
+++ hbase/branches/0.92/src/main/java/org/apache/hadoop/hbase/regionserver/SplitTransaction.java Mon Oct 17 22:34:05 2011
@@ -287,13 +287,24 @@ public class SplitTransaction {
     this.journal.add(JournalEntry.STARTED_REGION_B_CREATION);
     HRegion b = createDaughterRegion(this.hri_b, this.parent.rsServices);
 
+    // This is the point of no return.  Adding subsequent edits to .META. as we
+    // do below when we do the daughter opens adding each to .META. can fail in
+    // various interesting ways the most interesting of which is a timeout
+    // BUT the edits all go through (See HBASE-3872).  IF we reach the PONR
+    // then subsequent failures need to crash out this regionserver; the
+    // server shutdown processing should be able to fix-up the incomplete split.
+    // The offlined parent will have the daughters as extra columns.  If
+    // we leave the daughter regions in place and do not remove them when we
+    // crash out, then they will have their references to the parent in place
+    // still and the server shutdown fixup of .META. will point to these
+    // regions.
+    // We should add PONR JournalEntry before offlineParentInMeta,so even if
+    // OfflineParentInMeta timeout,this will cause regionserver exit,and then
+    // master ServerShutdownHandler will fix daughter & avoid data loss. See (
+    // HBASE-4562).
+    this.journal.add(JournalEntry.PONR);
+
     // Edit parent in meta.  Offlines parent region and adds splita and splitb.
-    // TODO: This can 'fail' by timing out against .META. but the edits could
-    // be applied anyways over on the server.  There is no way to tell for sure.
-    // We could try and get the edits again subsequent to their application
-    // whether we fail or not but that could fail too.  We should probably move
-    // the PONR to here before the edits go in but could mean we'd abort the
-    // regionserver when we didn't need to; i.e. the edits did not make it in.
     if (!testing) {
       MetaEditor.offlineParentInMeta(server.getCatalogTracker(),
         this.parent.getRegionInfo(), a.getRegionInfo(), b.getRegionInfo());
@@ -313,18 +324,6 @@ public class SplitTransaction {
   /* package */void openDaughters(final Server server,
       final RegionServerServices services, HRegion a, HRegion b)
       throws IOException {
-    // This is the point of no return.  Adding subsequent edits to .META. as we
-    // do below when we do the daughter opens adding each to .META. can fail in
-    // various interesting ways the most interesting of which is a timeout
-    // BUT the edits all go through (See HBASE-3872).  IF we reach the PONR
-    // then subsequent failures need to crash out this regionserver; the
-    // server shutdown processing should be able to fix-up the incomplete split.
-    // The offlined parent will have the daughters as extra columns.  If
-    // we leave the daughter regions in place and do not remove them when we
-    // crash out, then they will have their references to the parent in place
-    // still and the server shutdown fixup of .META. will point to these
-    // regions.
-    this.journal.add(JournalEntry.PONR);
     boolean stopped = server != null && server.isStopped();
     boolean stopping = services != null && services.isStopping();
     // TODO: Is this check needed here?