From 3be9941f763e732d435e3d04bc169153713040fc Mon Sep 17 00:00:00 2001
From: gojomo <gojomo@daa5b2f2-a927-0410-8b2d-f5f262fa301a>
Date: Mon, 8 Nov 2010 18:54:03 +0000
Subject: [PATCH] Resolve deadlock seen after latest changes * AbstractFrontier
     (drainInbound) don't assume current thread will be able to take() full
 batch; poll() and exit early if other threads have drained queue first

---
 .../java/org/archive/crawler/frontier/AbstractFrontier.java  | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/engine/src/main/java/org/archive/crawler/frontier/AbstractFrontier.java b/engine/src/main/java/org/archive/crawler/frontier/AbstractFrontier.java
index ab9981ba..9551661e 100644
--- a/engine/src/main/java/org/archive/crawler/frontier/AbstractFrontier.java
+++ b/engine/src/main/java/org/archive/crawler/frontier/AbstractFrontier.java
@@ -473,7 +473,10 @@ public abstract class AbstractFrontier
     protected void drainInbound() throws InterruptedException {
         int batch = inbound.size();
         for(int i = 0; i < batch; i++) {
-            InEvent ev = inbound.take();
+            InEvent ev = inbound.poll();
+            if(ev==null) {
+                break;
+            }
             synchronized(this) {
                 ev.process();
             }