From 866a2c6c42a1c9625c31cc759518e829c42aea6c Mon Sep 17 00:00:00 2001
From: Michael Stack <stack@apache.org>
Date: Tue, 17 Sep 2013 03:34:51 +0000
Subject: [PATCH] HBASE-9467 write can be totally blocked temporarily by a
 write-heavy region

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1523881 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop/hbase/regionserver/HRegion.java    | 63 +++----------------
 .../hadoop/hbase/HBaseTestingUtility.java     | 15 ++++-
 2 files changed, 21 insertions(+), 57 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
index 87d6d26e605..786dd97ceb7 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
@@ -2511,66 +2511,17 @@ public class HRegion implements HeapSize { // , Writable{
   /*
    * Check if resources to support an update.
    *
-   * Here we synchronize on HRegion, a broad scoped lock.  Its appropriate
-   * given we're figuring in here whether this region is able to take on
-   * writes.  This is only method with a synchronize (at time of writing),
-   * this and the synchronize on 'this' inside in internalFlushCache to send
-   * the notify.
-   */
+   * We throw RegionTooBusyException if above memstore limit
+   * and expect client to retry using some kind of backoff
+  */
   private void checkResources()
-      throws RegionTooBusyException, InterruptedIOException {
-
+    throws RegionTooBusyException {
     // If catalog region, do not impose resource constraints or block updates.
     if (this.getRegionInfo().isMetaRegion()) return;
 
-    boolean blocked = false;
-    long startTime = 0;
-    while (this.memstoreSize.get() > this.blockingMemStoreSize) {
+    if (this.memstoreSize.get() > this.blockingMemStoreSize) {
       requestFlush();
-      if (!blocked) {
-        startTime = EnvironmentEdgeManager.currentTimeMillis();
-        LOG.info("Blocking updates for '" + Thread.currentThread().getName() +
-          "' on region " + Bytes.toStringBinary(getRegionName()) +
-          ": memstore size " +
-          StringUtils.humanReadableInt(this.memstoreSize.get()) +
-          " is >= than blocking " +
-          StringUtils.humanReadableInt(this.blockingMemStoreSize) + " size");
-      }
-      long now = EnvironmentEdgeManager.currentTimeMillis();
-      long timeToWait = startTime + busyWaitDuration - now;
-      if (timeToWait <= 0L) {
-        final long totalTime = now - startTime;
-        this.updatesBlockedMs.add(totalTime);
-        LOG.info("Failed to unblock updates for region " + this + " '"
-          + Thread.currentThread().getName() + "' in " + totalTime
-          + "ms. The region is still busy.");
-        throw new RegionTooBusyException("region is flushing");
-      }
-      blocked = true;
-      synchronized(this) {
-        try {
-          wait(Math.min(timeToWait, threadWakeFrequency));
-        } catch (InterruptedException ie) {
-          final long totalTime = EnvironmentEdgeManager.currentTimeMillis() - startTime;
-          if (totalTime > 0) {
-            this.updatesBlockedMs.add(totalTime);
-          }
-          LOG.info("Interrupted while waiting to unblock updates for region "
-            + this + " '" + Thread.currentThread().getName() + "'");
-          InterruptedIOException iie = new InterruptedIOException();
-          iie.initCause(ie);
-          throw iie;
-        }
-      }
-    }
-    if (blocked) {
-      // Add in the blocked time if appropriate
-      final long totalTime = EnvironmentEdgeManager.currentTimeMillis() - startTime;
-      if(totalTime > 0 ){
-        this.updatesBlockedMs.add(totalTime);
-      }
-      LOG.info("Unblocking updates for region " + this + " '"
-          + Thread.currentThread().getName() + "'");
+      throw new RegionTooBusyException("above memstore limit");
     }
   }
 
@@ -4661,6 +4612,7 @@ public class HRegion implements HeapSize { // , Writable{
     long txid = 0;
 
     checkReadOnly();
+    checkResources();
     // Lock row
     startRegionOperation(Operation.APPEND);
     this.writeRequestsCount.increment();
@@ -4835,6 +4787,7 @@ public class HRegion implements HeapSize { // , Writable{
     long txid = 0;
 
     checkReadOnly();
+    checkResources();
     // Lock row
     startRegionOperation(Operation.INCREMENT);
     this.writeRequestsCount.increment();
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
index e23a29bd5ac..534d49a651c 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
@@ -1655,8 +1655,19 @@ public class HBaseTestingUtility extends HBaseCommonTestingUtility {
           Put put = new Put(k);
           put.add(f, null, k);
           if (r.getLog() == null) put.setDurability(Durability.SKIP_WAL);
-          r.put(put);
-          rowCount++;
+
+          int preRowCount = rowCount;
+          int pause = 10;
+          int maxPause = 1000;
+          while (rowCount == preRowCount) {
+            try {
+              r.put(put);
+              rowCount++;
+            } catch (RegionTooBusyException e) {
+              pause = (pause * 2 >= maxPause) ? maxPause : pause * 2;
+              Threads.sleep(pause);
+            }
+          }
         }
       }
       if (flush) {