diff --git a/CHANGES.txt b/CHANGES.txt
index 2a30030bf39..8807123c742 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -214,6 +214,7 @@ Release 0.91.0 - Unreleased
                (dhruba borthakur)
    HBASE-3797  StoreFile Level Compaction Locking
    HBASE-1476  Multithreaded Compactions
+   HBASE-3877  Determine Proper Defaults for Compaction ThreadPools
 
   TASKS
    HBASE-3559  Move report of split to master OFF the heartbeat channel
diff --git a/src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplitThread.java b/src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplitThread.java
index 8326c02cca8..2cf39174fff 100644
--- a/src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplitThread.java
+++ b/src/main/java/org/apache/hadoop/hbase/regionserver/CompactSplitThread.java
@@ -28,6 +28,8 @@ import java.util.concurrent.TimeUnit;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.HTableDescriptor;
 import org.apache.hadoop.hbase.regionserver.compactions.CompactionRequest;
 
 import com.google.common.base.Preconditions;
@@ -70,9 +72,19 @@ public class CompactSplitThread implements CompactionRequestor {
     int largeThreads = Math.max(1, conf.getInt(
         "hbase.regionserver.thread.compaction.large", 1));
     int smallThreads = conf.getInt(
-        "hbase.regionserver.thread.compaction.small", 0);
-    throttleSize = conf.getLong(
-        "hbase.regionserver.thread.compaction.throttle", 0);
+        "hbase.regionserver.thread.compaction.small", 1);
+    if (conf.get("hbase.regionserver.thread.compaction.throttle") != null) {
+      throttleSize = conf.getLong(
+          "hbase.regionserver.thread.compaction.throttle", 0);
+    } else {
+      // we have a complicated default. see HBASE-3877
+      long flushSize = conf.getLong("hbase.hregion.memstore.flush.size",
+          HTableDescriptor.DEFAULT_MEMSTORE_FLUSH_SIZE);
+      long splitSize = conf.getLong("hbase.hregion.max.filesize",
+          HConstants.DEFAULT_MAX_FILE_SIZE);
+      throttleSize = Math.min(flushSize * 2, splitSize / 2);
+    }
+
     int splitThreads = conf.getInt("hbase.regionserver.thread.split", 1);
 
     // if we have throttle threads, make sure the user also specified size