[HIVE-7741] Don't synchronize WriterImpl.addRow() when dynamic.partition is enabled

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 0.13.1
• Component/s: File Formats
• Labels: performance

Environment

Loading into orc

• Assignee: Prasanth Jayachandran
• Reporter: Mostafa Mokhtar
• Created: 15/Aug/14 19:00
• Updated: 07/Jul/15 22:22
• Resolved: 07/Jul/15 22:22

Description

When loading into an un-paritioned ORC table WriterImpl$StructTreeWriter.write method is synchronized.

When hive.optimize.sort.dynamic.partition is enabled the current thread will be the only writer and the synchronization is not needed.

Also checking for memory per row is an over kill , this can be done per 1K rows or such

  public void addRow(Object row) throws IOException {
    synchronized (this) {
      treeWriter.write(row);
      rowsInStripe += 1;
      if (buildIndex) {
        rowsInIndex += 1;

        if (rowsInIndex >= rowIndexStride) {
          createRowIndexEntry();
        }
      }
    }
    memoryManager.addedRow();
  }

This can improve ORC load performance by 7%

Stack Trace	Sample Count	Percentage(%)
WriterImpl.addRow(Object)	5,852	65.782
   WriterImpl$StructTreeWriter.write(Object)	5,163	58.037
   MemoryManager.addedRow()	666	7.487
      MemoryManager.notifyWriters()	648	7.284
         WriterImpl.checkMemory(double)	645	7.25
            WriterImpl.flushStripe()	643	7.228
               WriterImpl$StructTreeWriter.writeStripe(OrcProto$StripeFooter$Builder, int)	584	6.565

Issue Links

• is related to: HIVE-10191 ORC: Cleanup writer per-row synchronization