From d777c198bdafbfee6484344f309d0f1faf9dccd2 Mon Sep 17 00:00:00 2001
From: Noah Levitt <nlevitt@archive.org>
Date: Thu, 24 Apr 2014 17:23:01 -0700
Subject: [PATCH] HER-2065 - in activateInactiveQueue() close synchronized
 block earlier, and move updateHighestWaiting() up to keep it inside the
 block; now the call to deactivateQueue() is not in the synchronized block, so
 the deadlock should be avoided (fix suggested by kenji)

---
 .../crawler/frontier/WorkQueueFrontier.java   | 37 ++++++++++---------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/engine/src/main/java/org/archive/crawler/frontier/WorkQueueFrontier.java b/engine/src/main/java/org/archive/crawler/frontier/WorkQueueFrontier.java
index 881e87c6..955d3fce 100644
--- a/engine/src/main/java/org/archive/crawler/frontier/WorkQueueFrontier.java
+++ b/engine/src/main/java/org/archive/crawler/frontier/WorkQueueFrontier.java
@@ -764,32 +764,33 @@ implements Closeable,
             Queue<String> queueOfWorkQueueKeys = entry.getValue();
 
             while (true) {
+                String workQueueKey;
                 synchronized (getInactiveQueuesByPrecedence()) {
-                    String workQueueKey = queueOfWorkQueueKeys.poll();
+                    workQueueKey = queueOfWorkQueueKeys.poll();
                     if (workQueueKey == null) {
                         break;
                     }
-
-                    WorkQueue candidateQ = (WorkQueue) this.allQueues.get(workQueueKey);
-                    if (candidateQ.getPrecedence() > expectedPrecedence) {
-                        // queue demoted since placed; re-deactivate
-                        deactivateQueue(candidateQ);
-                        candidateQ.makeDirty();
-                        continue; 
-                    }
-
                     updateHighestWaiting(expectedPrecedence);
-                    try {
-                        readyClassQueues.put(workQueueKey);
-                    } catch (InterruptedException e) {
-                        throw new RuntimeException(e); 
-                    } 
-                    
-                    return true; 
                 }
+
+                WorkQueue candidateQ = (WorkQueue) this.allQueues.get(workQueueKey);
+                if (candidateQ.getPrecedence() > expectedPrecedence) {
+                    // queue demoted since placed; re-deactivate
+                    deactivateQueue(candidateQ);
+                    candidateQ.makeDirty();
+                    continue;
+                }
+
+                try {
+                    readyClassQueues.put(workQueueKey);
+                } catch (InterruptedException e) {
+                    throw new RuntimeException(e);
+                }
+
+                return true;
             }
         }
-        
+
         return false;
     }