[HIVE-10191] ORC: Cleanup writer per-row synchronization

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.2.0
• Fix Version/s: 1.3.0, 2.0.0
• Component/s: File Formats
• Labels: TODOC1.3 TODOC2.0
• Release Note: Remove per-row synchronization from ORC WriterImpl
• Assignee: Gopal Vijayaraghavan
• Reporter: Gopal Vijayaraghavan
• Created: 02/Apr/15 07:14
• Updated: 16/Feb/16 23:51
• Resolved: 02/Jul/15 22:25

Description

ORC writers were originally meant to be thread-safe, but in the present day implementation each ORC writer is entirely share-nothing which converts most of the synchronized blocks in ORC as entirely uncontested locks.

These uncontested locks prevent the JVM from inlining/optimizing these methods, while adding no extra thread-safety to the ORC writers.

Issue Links

• incorporates: HIVE-10174 LLAP: ORC MemoryManager is singleton synchronized
• relates to: HIVE-7741 Don't synchronize WriterImpl.addRow() when dynamic.partition is enabled