[HIVE-20321] Vectorization: Cut down memory size of 1 col VectorHashKeyWrapper to <1 CacheLine

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.0-alpha-1
• Assignee: Matt McCline
• Reporter: Gopal Vijayaraghavan
• Created: 06/Aug/18 17:28
• Updated: 17/Nov/22 08:54
• Resolved: 17/Aug/18 13:10

Description

With a full sized LLAP instance, the memory size of the VectorHashKeyWrapper is bigger than the low Xmx JVMs.

***** 64-bit VM: **********************************************************
org.apache.hadoop.hive.ql.exec.vector.VectorHashKeyWrapper object internals:
 OFFSET  SIZE                                                                     TYPE DESCRIPTION                                  VALUE
      0    16                                                                          (object header)                              N/A
     16     4                                                                      int VectorHashKeyWrapper.hashcode                N/A
     20     4                                                                          (alignment/padding gap)                     
     24     8                                                                   long[] VectorHashKeyWrapper.longValues              N/A
     32     8                                                                 double[] VectorHashKeyWrapper.doubleValues            N/A
     40     8                                                                 byte[][] VectorHashKeyWrapper.byteValues              N/A
     48     8                                                                    int[] VectorHashKeyWrapper.byteStarts              N/A
     56     8                                                                    int[] VectorHashKeyWrapper.byteLengths             N/A
     64     8                   org.apache.hadoop.hive.serde2.io.HiveDecimalWritable[] VectorHashKeyWrapper.decimalValues           N/A
     72     8                                                     java.sql.Timestamp[] VectorHashKeyWrapper.timestampValues         N/A
     80     8                 org.apache.hadoop.hive.common.type.HiveIntervalDayTime[] VectorHashKeyWrapper.intervalDayTimeValues   N/A
     88     8                                                                boolean[] VectorHashKeyWrapper.isNull                  N/A
     96     8   org.apache.hadoop.hive.ql.exec.vector.VectorHashKeyWrapper.HashContext VectorHashKeyWrapper.hashCtx                 N/A
Instance size: 104 bytes
Space losses: 4 bytes internal + 0 bytes external = 4 bytes total

Pulling this up to a parent class allows for this to be cut down to 32 bytes for the single column case.

Issue Links

• links to: RB #68356