YARN-9833. Race condition when DirectoryCollection.checkDirs() runs during container launch. Contributed by Peter Bacsko.

(cherry picked from commit c474e24c0b73c0f52a7d5af2495355f4a0799344)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/DirectoryCollection.java

@@ -50,6 +50,7 @@ import org.apache.hadoop.yarn.conf.YarnConfiguration;
 import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableList;
 
 /**
  * Manages a list of local storage directories.
@@ -277,7 +278,7 @@ public class DirectoryCollection {
   List<String> getGoodDirs() {
     this.readLock.lock();
     try {
-      return Collections.unmodifiableList(localDirs);
+      return ImmutableList.copyOf(localDirs);
     } finally {
       this.readLock.unlock();
     }
@@ -289,7 +290,7 @@ public class DirectoryCollection {
   List<String> getFailedDirs() {
     this.readLock.lock();
     try {
-      return Collections.unmodifiableList(
+      return ImmutableList.copyOf(
           DirectoryCollection.concat(errorDirs, fullDirs));
     } finally {
       this.readLock.unlock();
@@ -302,7 +303,7 @@ public class DirectoryCollection {
   List<String> getFullDirs() {
     this.readLock.lock();
     try {
-      return Collections.unmodifiableList(fullDirs);
+      return ImmutableList.copyOf(fullDirs);
     } finally {
       this.readLock.unlock();
     }