[YARN-7133] Clean up lock-try order in fair scheduler

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha4
• Fix Version/s: 3.2.0
• Component/s: fairscheduler
• Labels: newbie
• Hadoop Flags: Reviewed
• Assignee: Szilard Nemeth
• Reporter: Daniel Templeton
• Created: 30/Aug/17 21:40
• Updated: 24/Jul/18 20:10
• Resolved: 24/Jul/18 19:47

Description

There are many places that follow the pattern:

try {
  lock.lock();
  ...
} finally {
  lock.unlock();
}

There are a couple of reasons that's a bad idea. The correct pattern is:

lock.lock();
try {
  ...
} finally {
  lock.unlock();
}