[jboss-jira] [JBoss JIRA] Commented: (JBCACHE-1316) recycleQueue.put() could block forever halting evictions and eventually any replications

recycleQueue.put() could block forever halting evictions and eventually any replications ---------------------------------------------------------------------------------------- Key: JBCACHE-1316 URL: http://jira.jboss.com/jira/browse/JBCACHE-1316 Project: JBoss Cache Issue Type: Bug Security Level: Public(Everyone can see) Components: Eviction Affects Versions: 2.1.0.GA, 1.4.1.SP8, 2.0.0.GA, 1.4.0.SP1 Reporter: Galder Zamarreno Assigned To: Galder Zamarreno In BaseEvictionAlgorithm, whenever we can't evict a node, we add it to the recycle queue: protected void evict(NodeEntry ne) { // NodeEntry ne = evictionQueue.getNodeEntry(fqn); if (ne != null) { evictionQueue.removeNodeEntry(ne); if (!this.evictCacheNode(ne.getFqn())) { try { recycleQueue.put(ne.getFqn()); } catch (InterruptedException e) { log.debug("InterruptedException", e); } } } } For that to happen, an Exception must have been thrown in: protected boolean evictCacheNode(Fqn fqn) { if (log.isTraceEnabled()) { log.trace("Attempting to evict cache node with fqn of " + fqn); } EvictionPolicy policy = region.getEvictionPolicy(); // Do an eviction of this node try { policy.evict(fqn); } catch (Exception e) { if (e instanceof TimeoutException) { log.warn("eviction of " + fqn + " timed out. Will retry later."); return false; } e.printStackTrace(); return false; } if (log.isTraceEnabled()) { log.trace("Eviction of cache node with fqn of " + fqn + " successful"); } return true; } In a production environment, specially if the user ignores warnings or Exceptions, we could end up blocking indefinitely in recycleQueue.put(ne.getFqn()); if there's no more room. If this deadlocks, evictions deadlock leading to either OOME or replication exceptions because no more events can be put in the eviction queue. Rather than calling put() on the EDU.oswego.cs.dl.util.concurrent.BoundedBuffer, we should call offer(Object x, long msecs) so that we never run the chance of blocking forever here again. Same thing happens for 2.x, it uses LinkedBlockingQueue and calls put() on it, which waits if necessary for space to become available. Now, the chances of this issue occurring in 2.x are lower because LinkedBlockingQueue is initialised with a capacity of 500000. In 1.4.x, the BoundedBuffer was initialised with the default capacity, which was 1024.