3 files changed, 21 insertions, 9 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/BazelWorkspaceStatusModule.java b/src/main/java/com/google/devtools/build/lib/bazel/BazelWorkspaceStatusModule.java
index bb77abc020..16f882fd11 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/BazelWorkspaceStatusModule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/BazelWorkspaceStatusModule.java
@@ -282,7 +282,6 @@ public class BazelWorkspaceStatusModule extends BlazeModule {
   }
 
   private class BazelStatusActionFactory implements WorkspaceStatusAction.Factory {
-    private String hostname;
 
     @Override
     public Map<String, String> createDummyWorkspaceStatus() {
@@ -312,11 +311,7 @@ public class BazelWorkspaceStatusModule extends BlazeModule {
      * changes during bazel server lifetime, bazel will not see the change.
      */
     private String getHostname() {
-      if (hostname == null) {
-        hostname = NetUtil.findShortHostName();
-      }
-
-      return hostname;
+      return NetUtil.getCachedShortHostName();
     }
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/exec/local/LocalSpawnRunner.java b/src/main/java/com/google/devtools/build/lib/exec/local/LocalSpawnRunner.java
index 57d757691d..9aed79b08d 100644
--- a/src/main/java/com/google/devtools/build/lib/exec/local/LocalSpawnRunner.java
+++ b/src/main/java/com/google/devtools/build/lib/exec/local/LocalSpawnRunner.java
@@ -90,7 +90,7 @@ public final class LocalSpawnRunner implements SpawnRunner {
     this.execRoot = execRoot;
     this.processWrapper = getProcessWrapper(execRoot, localOs).getPathString();
     this.localExecutionOptions = Preconditions.checkNotNull(localExecutionOptions);
-    this.hostName = NetUtil.findShortHostName();
+    this.hostName = NetUtil.getCachedShortHostName();
     this.resourceManager = resourceManager;
     this.useProcessWrapper = useProcessWrapper;
     this.productName = productName;
diff --git a/src/main/java/com/google/devtools/build/lib/util/NetUtil.java b/src/main/java/com/google/devtools/build/lib/util/NetUtil.java
index f22146a71d..dc2ce8867e 100644
--- a/src/main/java/com/google/devtools/build/lib/util/NetUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/util/NetUtil.java
@@ -21,14 +21,31 @@ import java.net.UnknownHostException;
  */
 public final class NetUtil {
 
+  private static String hostname;
+
   private NetUtil() {
   }
 
   /**
+   * Returns the *cached* short hostname (computed at most once per the lifetime of a server). Can
+   * take seconds to complete when the cache is cold.
+   */
+  public static String getCachedShortHostName() {
+    if (hostname == null) {
+      synchronized (NetUtil.class) {
+        if (hostname == null) {
+          hostname = computeShortHostName();
+        }
+      }
+    }
+    return computeShortHostName();
+  }
+
+  /**
    * Returns the short hostname or <code>unknown</code> if the host name could not be determined.
-   * Performs reverse DNS lookup and can take seconds to complete!
+   * Performs reverse DNS lookup and can take seconds to complete.
    */
-  public static String findShortHostName() {
+  private static String computeShortHostName() {
     try {
       return InetAddress.getLocalHost().getHostName();
     } catch (UnknownHostException e) {