[SPARK-4714] BlockManager should check whether blocks have already been removed Checking block is null or not after having gotten info.lock in remove block method

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.1.0
• Fix Version/s: 1.0.3, 1.1.2, 1.2.1, 1.3.0
• Component/s: Block Manager, Spark Core
• Target Version/s: 1.0.3, 1.1.2, 1.2.1, 1.3.0
• Assignee: SuYan
• Reporter: SuYan
• Created: 03/Dec/14 07:16
• Updated: 17/May/20 18:20
• Resolved: 17/Dec/14 20:17

Description

in removeBlock()/ dropOldBlock()/ dropFromMemory()
all have the same logic:
1. info = blockInfo.get(id)
2. if (info != null)
3. info.synchronized

there may be a possibility that while one thread got info.lock while the previous thread already removed from blockinfo in info.lock.

but one thing in current code, That not check info is null or not, while get info.lock to remove block, will not cause any errors.

Issue Links

• links to: [Github] Pull Request #3574 (suyanNone)