Github user phrocker commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/60#discussion_r48753072
--- Diff:
server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Scanner.java ---
@@ -38,100 +40,126 @@
private ScanDataSource isolatedDataSource;
private boolean sawException = false;
private boolean scanClosed = false;
+ protected Semaphore scannerSemaphore;
Scanner(Tablet tablet, Range range, ScanOptions options) {
this.tablet = tablet;
this.range = range;
this.options = options;
+ scannerSemaphore = new Semaphore(1, true);
--- End diff --
My only reason for enforcing fairness was that we likely only have a single
thread doing reads ( otherwise we'd have different sessions ); however, we will
have another thread doing a close. I wanted to enforce order in the event that
the read should occur first. In rethinking this I'm not terribly certain this a
problem.
As we discussed I only used a semaphore based on the aforementioned
assumption of a single thread doing reads within the scanner. I'm not tied to
the idea.
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