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From: alexlevenson@apache.org
To: commits@parquet.incubator.apache.org
Message-Id: <39f2d6ccf2cd49b8b8f0a226f38b68fd@git.apache.org>
Subject: incubator-parquet-mr git commit: PARQUET-217 Use simpler heuristic in
 MemoryManager
Date: Fri, 13 Mar 2015 19:55:02 +0000 (UTC)

Repository: incubator-parquet-mr
Updated Branches:
  refs/heads/master 77826fda8 -> 9ee3a1617


PARQUET-217 Use simpler heuristic in MemoryManager

We found that the heuristic of throwing when:
```
minMemoryAllocation > 0 && newSize/maxColCount < minMemoryAllocation
```
in MemoryManager is not really valid when you have many (3k +) columns, due to the division by the number of columns.
This check throws immediately when writing a single file with a 3GB heap and > 3K columns.

This PR introduces a simpler heuristic, which is a min scale, and we throw when the MemoryManager's scale gets too small. By default I chose 25%, but I'm happy to change that to something else.

For backwards compatibility I've left the original check in, but it's not executed by default anymore, to get this behavior the min chunk size will have to be set in the hadoop configuration. I'm also open to removing it entirely if we don't think we need it anymore.

What do you think?
@danielcweeks @rdblue @dongche @julienledem

Author: Alex Levenson <alexlevenson@twitter.com>

Closes #143 from isnotinvain/alexlevenson/mem-manager-heuristic and squashes the following commits:

acda66f [Alex Levenson] Add units to exception
10237c6 [Alex Levenson] Decouple DEFAULT_MIN_MEMORY_ALLOCATION from DEFAULT_PAGE_SIZE
29c9881 [Alex Levenson] Use an absolute minimum on rowgroup size, only apply when scale < 1
8877125 [Alex Levenson] Merge branch 'master' into alexlevenson/mem-manager-heuristic
e5117a0 [Alex Levenson] Merge branch 'master' into alexlevenson/mem-manager-heuristic
6ee5f46 [Alex Levenson] Use simpler heuristic in MemoryManager


Project: http://git-wip-us.apache.org/repos/asf/incubator-parquet-mr/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-parquet-mr/commit/9ee3a161
Tree: http://git-wip-us.apache.org/repos/asf/incubator-parquet-mr/tree/9ee3a161
Diff: http://git-wip-us.apache.org/repos/asf/incubator-parquet-mr/diff/9ee3a161

Branch: refs/heads/master
Commit: 9ee3a16179cb65f5fe4170257ab7cde558f1dbeb
Parents: 77826fd
Author: Alex Levenson <alexlevenson@twitter.com>
Authored: Fri Mar 13 12:54:58 2015 -0700
Committer: Alex Levenson <alexlevenson@twitter.com>
Committed: Fri Mar 13 12:54:58 2015 -0700

----------------------------------------------------------------------
 .../src/main/java/parquet/hadoop/MemoryManager.java       | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/incubator-parquet-mr/blob/9ee3a161/parquet-hadoop/src/main/java/parquet/hadoop/MemoryManager.java
----------------------------------------------------------------------
diff --git a/parquet-hadoop/src/main/java/parquet/hadoop/MemoryManager.java b/parquet-hadoop/src/main/java/parquet/hadoop/MemoryManager.java
index 7bb0665..9724868 100644
--- a/parquet-hadoop/src/main/java/parquet/hadoop/MemoryManager.java
+++ b/parquet-hadoop/src/main/java/parquet/hadoop/MemoryManager.java
@@ -40,7 +40,7 @@ import java.util.Map;
 public class MemoryManager {
   private static final Log LOG = Log.getLog(MemoryManager.class);
   static final float DEFAULT_MEMORY_POOL_RATIO = 0.95f;
-  static final long DEFAULT_MIN_MEMORY_ALLOCATION = ParquetWriter.DEFAULT_PAGE_SIZE;
+  static final long DEFAULT_MIN_MEMORY_ALLOCATION = 1 * 1024 * 1024; // 1MB
   private final float memoryPoolRatio;
 
   private final long totalMemoryPool;
@@ -121,10 +121,10 @@ public class MemoryManager {
 
     for (Map.Entry<InternalParquetRecordWriter, Long> entry : writerList.entrySet()) {
       long newSize = (long) Math.floor(entry.getValue() * scale);
-      if(minMemoryAllocation > 0 && newSize/maxColCount < minMemoryAllocation) {
-          throw new ParquetRuntimeException(String.format("New Memory allocation %d"+
-          " exceeds minimum allocation size %d with largest schema having %d columns",
-              newSize, minMemoryAllocation, maxColCount)){};
+      if(scale < 1.0 && minMemoryAllocation > 0 && newSize < minMemoryAllocation) {
+          throw new ParquetRuntimeException(String.format("New Memory allocation %d bytes" +
+          " is smaller than the minimum allocation size of %d bytes.",
+              newSize, minMemoryAllocation)){};
       }
       entry.getKey().setRowGroupSizeThreshold(newSize);
       LOG.debug(String.format("Adjust block size from %,d to %,d for writer: %s",