From ee0fd06de73e0191365549fa7c4f6c71c1bbc08d Mon Sep 17 00:00:00 2001
From: Wenning Ding <wenningd@amazon.com>
Date: Wed, 30 Oct 2019 11:48:21 -0700
Subject: [PATCH] synchronized lock on conf object instead of class

---
 .../HoodieParquetRealtimeInputFormat.java       | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/hudi-hadoop-mr/src/main/java/org/apache/hudi/hadoop/realtime/HoodieParquetRealtimeInputFormat.java b/hudi-hadoop-mr/src/main/java/org/apache/hudi/hadoop/realtime/HoodieParquetRealtimeInputFormat.java
index 3e4272479..ba325e15b 100644
--- a/hudi-hadoop-mr/src/main/java/org/apache/hudi/hadoop/realtime/HoodieParquetRealtimeInputFormat.java
+++ b/hudi-hadoop-mr/src/main/java/org/apache/hudi/hadoop/realtime/HoodieParquetRealtimeInputFormat.java
@@ -200,14 +200,17 @@ public class HoodieParquetRealtimeInputFormat extends HoodieParquetInputFormat i
   /**
    * Hive will append read columns' ids to old columns' ids during getRecordReader. In some cases, e.g. SELECT COUNT(*),
    * the read columns' id is an empty string and Hive will combine it with Hoodie required projection ids and becomes
-   * e.g. ",2,0,3" and will cause an error. This method is used to avoid this situation.
+   * e.g. ",2,0,3" and will cause an error. Actually this method is a temporary solution because the real bug is from
+   * Hive. Hive has fixed this bug after 3.0.0, but the version before that would still face this problem. (HIVE-22438)
    */
-  private static synchronized Configuration cleanProjectionColumnIds(Configuration conf) {
-    String columnIds = conf.get(ColumnProjectionUtils.READ_COLUMN_IDS_CONF_STR);
-    if (!columnIds.isEmpty() && columnIds.charAt(0) == ',') {
-      conf.set(ColumnProjectionUtils.READ_COLUMN_IDS_CONF_STR, columnIds.substring(1));
-      if (LOG.isDebugEnabled()) {
-        LOG.debug("The projection Ids: {" + columnIds + "} start with ','. First comma is removed");
+  private static Configuration cleanProjectionColumnIds(Configuration conf) {
+    synchronized (conf) {
+      String columnIds = conf.get(ColumnProjectionUtils.READ_COLUMN_IDS_CONF_STR);
+      if (!columnIds.isEmpty() && columnIds.charAt(0) == ',') {
+        conf.set(ColumnProjectionUtils.READ_COLUMN_IDS_CONF_STR, columnIds.substring(1));
+        if (LOG.isDebugEnabled()) {
+          LOG.debug("The projection Ids: {" + columnIds + "} start with ','. First comma is removed");
+        }
       }
     }
     return conf;