[HBASE-15203] Reduce garbage created by path.toString() during Checksum verification

• Type: Sub-task
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.3.0, 2.0.0
• Component/s: regionserver
• Hadoop Flags: Reviewed
• Assignee: ramkrishna.s.vasudevan
• Reporter: ramkrishna.s.vasudevan
• Created: 02/Feb/16 06:24
• Updated: 01/Jul/22 21:32
• Resolved: 12/Feb/16 05:56

Description

When we try to read a block we do checksum verification for which we need the file name in which the block belongs to. So we do Path.toString() every time. This seems to create around 163MB of char[] that is garbage collected in a simple scan run. It is also visible in writes but the impact is lesser. In overall write/read profile the top 2 factors are byte[] and char[]. This toString() can easily be avoided and reduce its share from the total. To make it more precise in 1 min of profiling, among the 1.8G of garbage created by StringBuilder.toString - this path.toString() was contributing around 3.5%. After the patch this is totally not there.