From 1974c83561d09cf73a575f992fbd8416e3354d20 Mon Sep 17 00:00:00 2001
From: Hendrik Saly <hendrikdev22@gmail.com>
Date: Mon, 4 May 2015 09:03:21 +0200
Subject: [PATCH] incorporated feedback from Peter

---
 .../java/org/apache/commons/lang3/ThreadUtils.java     | 10 ++++++----
 .../java/org/apache/commons/lang3/ThreadUtilsTest.java | 10 +++++++---
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/ThreadUtils.java b/src/main/java/org/apache/commons/lang3/ThreadUtils.java
index 602facee9..758baf944 100644
--- a/src/main/java/org/apache/commons/lang3/ThreadUtils.java
+++ b/src/main/java/org/apache/commons/lang3/ThreadUtils.java
@@ -127,8 +127,9 @@ public class ThreadUtils {
         }
 
         final Collection<Thread> result = new ArrayList<Thread>();
+        NamePredicate threadNamePredicate = null;
         for(final ThreadGroup group : findThreadGroups(new NamePredicate(threadGroupName))) {
-            result.addAll(findThreads(group, false, new NamePredicate(threadName)));
+            result.addAll(findThreads(group, false, threadNamePredicate==null?(threadNamePredicate=new NamePredicate(threadName)):threadNamePredicate));
         }
         return Collections.unmodifiableCollection(result);
     }
@@ -223,7 +224,7 @@ public class ThreadUtils {
     public static Thread findThreadById(final long threadId) {
         final Collection<Thread> result = findThreads(new ThreadIdPredicate(threadId));
 
-        if(!result.iterator().hasNext()) {
+        if(result.isEmpty()) {
             return null;
         } else {
             return result.iterator().next();
@@ -406,7 +407,6 @@ public class ThreadUtils {
             throw new IllegalArgumentException("The predicate must not be null");
         }
 
-        final List<Thread> result = new ArrayList<Thread>();
         int count = group.activeCount();
         Thread[] threads;
         do {
@@ -414,6 +414,7 @@ public class ThreadUtils {
             count = group.enumerate(threads, recurse);
         } while (count >= threads.length);
 
+        final List<Thread> result = new ArrayList<Thread>(count);
         for (int i = 0; i < count; ++i) {
             if (predicate.test(threads[i])) {
                 result.add(threads[i]);
@@ -440,7 +441,7 @@ public class ThreadUtils {
         if (predicate == null) {
             throw new IllegalArgumentException("The predicate must not be null");
         }
-        final List<ThreadGroup> result = new ArrayList<ThreadGroup>();
+        
         int count = group.activeGroupCount();
         ThreadGroup[] threadGroups;
         do {
@@ -449,6 +450,7 @@ public class ThreadUtils {
         }
         while(count >= threadGroups.length);
 
+        final List<ThreadGroup> result = new ArrayList<ThreadGroup>(count);
         for(int i = 0; i<count; ++i) {
             if(predicate.test(threadGroups[i])) {
                 result.add(threadGroups[i]);
diff --git a/src/test/java/org/apache/commons/lang3/ThreadUtilsTest.java b/src/test/java/org/apache/commons/lang3/ThreadUtilsTest.java
index df963ddaf..dd20abe51 100644
--- a/src/test/java/org/apache/commons/lang3/ThreadUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/ThreadUtilsTest.java
@@ -296,7 +296,9 @@ public class ThreadUtilsTest {
         final ThreadGroup threadGroup4 = new ThreadGroup(threadGroup2, "thread_group_4__");
         final ThreadGroup threadGroup5 = new ThreadGroup(threadGroup1, "thread_group_5__");
         final ThreadGroup threadGroup6 = new ThreadGroup(threadGroup4, "thread_group_6__");
-        final List<ThreadGroup> threadGroups = Arrays.asList(threadGroup1,threadGroup2,threadGroup3,threadGroup4,threadGroup5,threadGroup6);
+        final ThreadGroup threadGroup7 = new ThreadGroup(threadGroup4, "thread_group_7__");
+        final ThreadGroup threadGroup7Doubled = new ThreadGroup(threadGroup4, "thread_group_7__");
+        final List<ThreadGroup> threadGroups = Arrays.asList(threadGroup1,threadGroup2,threadGroup3,threadGroup4,threadGroup5,threadGroup6, threadGroup7, threadGroup7Doubled);
 
         final Thread t1 = new TestThread("thread1_X__");
         final Thread t2 = new TestThread(threadGroup1, "thread2_X__");
@@ -308,7 +310,9 @@ public class ThreadUtilsTest {
         final Thread t8 = new TestThread(threadGroup4, "thread8_X__");
         final Thread t9 = new TestThread(threadGroup6, "thread9_X__");
         final Thread t10 = new TestThread(threadGroup3, "thread10_X__");
-        final List<Thread> threads = Arrays.asList(t1,t2,t3,t4,t5,t6,t7,t8,t9,t10);
+        final Thread t11 = new TestThread(threadGroup7, "thread11_X__");
+        final Thread t11Doubled = new TestThread(threadGroup7Doubled, "thread11_X__");
+        final List<Thread> threads = Arrays.asList(t1,t2,t3,t4,t5,t6,t7,t8,t9,t10, t11, t11Doubled);
 
         try {
             for (final Iterator iterator = threads.iterator(); iterator.hasNext();) {
@@ -320,7 +324,7 @@ public class ThreadUtilsTest {
             assertTrue(ThreadUtils.findThreads(ThreadUtils.ALWAYS_TRUE_PREDICATE).size() >= 11);
             assertEquals(1, ThreadUtils.findThreadsByName(t4.getName(), threadGroup3.getName()).size());
             assertEquals(0, ThreadUtils.findThreadsByName(t4.getName(), threadGroup2.getName()).size());
-           
+            assertEquals(2, ThreadUtils.findThreadsByName(t11.getName(), threadGroup7.getName()).size());
         }finally {
             for (final Iterator iterator = threads.iterator(); iterator.hasNext();) {
                 final Thread thread = (Thread) iterator.next();