JDK-6189072 : Add sometimes fails after clear or drainTo in LinkedBlockingQueue
  • Type: Bug
  • Component: core-libs
  • Sub-Component: java.util.concurrent
  • Affected Version: 6
  • Priority: P2
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2004-11-01
  • Updated: 2010-04-02
  • Resolved: 2004-11-20
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Other JDK 6
5.0u2Fixed 6 b14Fixed
Related Reports
Relates :  
JDK-6215625 - LinkedBlockingQueue.extract throws NPE
Description
When the queue is not empty before a call to drainTo or
  clear, subsequent added elements are not accessible.
###@###.### 11/1/04 22:30 GMT
Comments
SUGGESTED FIX --- /u/martin/ws/mustang/src/share/classes/java/util/concurrent/LinkedBlockingQueue.java 2004-08-27 15:54:58.702764000 -0700 +++ /u/martin/ws/jsr166/src/share/classes/java/util/concurrent/LinkedBlockingQueue.java 2004-10-31 14:54:45.663173000 -0800 @@ -526,6 +526,8 @@ fullyLock(); try { head.next = null; + head.item = null; + last = head; if (count.getAndSet(0) == capacity) notFull.signalAll(); } finally { @@ -543,6 +545,7 @@ try { first = head.next; head.next = null; + last = head; if (count.getAndSet(0) == capacity) notFull.signalAll(); } finally { @@ -555,6 +558,7 @@ p.item = null; ++n; } + head.item = null; // Just for GC, so OK if not within lock return n; } @@ -577,6 +581,9 @@ } if (n != 0) { head.next = p; + head.item = null; + if (p == null) + last = head; if (count.getAndAdd(-n) == capacity) notFull.signalAll(); } ###@###.### 11/1/04 22:30 GMT
01-11-2004
EVALUATION This is due to lines of clear() being dropped by mistake sometime during development, and then propagated into the newer drainTo methods. Somehow no TCK or JTREG tests tested this case. ###@###.### 11/1/04 22:30 GMT
01-11-2004