[ARTEMIS-710] Avoid inefficient iteration over Map

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.4.0
• Fix Version/s: 1.4.0
• Component/s: Broker
• Assignee: Unassigned
• Reporter: Martin Styk
• Created: 31/Aug/16 14:30
• Updated: 03/Oct/16 07:31
• Resolved: 03/Oct/16 07:28

Description

On few places in Artemis code, inefficient iteration over Map object is present.
Example

  Map<Thread, StackTraceElement[]> threadMap = Thread.getAllStackTraces();
         for (Thread thread : threadMap.keySet()) {
           StackTraceElement[] stack = threadMap.get(thread);
           ....

To make it more efficient, we should use Map.Entry instead of getting keySet and than finding corresponding value.
Places where this could be changed

• ScaleDownHandler#scaleDownDuplicateIDs
• PostOfficeJournalLoader#recoverPendingPageCounters
• ActiveMQTestBase#tearDown

Issue Links

• links to: GitHub Pull Request #745