YARN-10593. Fix incorrect string comparison in GpuDiscoverer. Contributed by Peter Bacsko

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/resourceplugin/gpu/GpuDiscoverer.java

@@ -284,11 +284,12 @@ public class GpuDiscoverer extends Configured {
       binaryPath = configuredBinaryFile;
       // If path exists but file name is incorrect don't execute the file
       String fileName = binaryPath.getName();
-      if (DEFAULT_BINARY_NAME.equals(fileName)) {
+      if (!DEFAULT_BINARY_NAME.equals(fileName)) {
         String msg = String.format("Please check the configuration value of"
-             +" %s. It should point to an %s binary.",
+             +" %s. It should point to an %s binary, which is now %s",
              YarnConfiguration.NM_GPU_PATH_TO_EXEC,
-             DEFAULT_BINARY_NAME);
+             DEFAULT_BINARY_NAME,
+             fileName);
         throwIfNecessary(new YarnException(msg), config);
         LOG.warn(msg);
       }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/containermanager/resourceplugin/gpu/TestGpuDiscoverer.java

@@ -79,12 +79,23 @@ public class TestGpuDiscoverer {
   }
 
   private File setupFakeBinary(Configuration conf) {
+    return setupFakeBinary(conf,
+        GpuDiscoverer.DEFAULT_BINARY_NAME, false);
+  }
+
+  private File setupFakeBinary(Configuration conf, String filename,
+      boolean useFullPath) {
     File fakeBinary;
     try {
       fakeBinary = new File(getTestParentFolder(),
-          GpuDiscoverer.DEFAULT_BINARY_NAME);
+          filename);
       touchFile(fakeBinary);
-      conf.set(YarnConfiguration.NM_GPU_PATH_TO_EXEC, getTestParentFolder());
+      if (useFullPath) {
+        conf.set(YarnConfiguration.NM_GPU_PATH_TO_EXEC,
+            fakeBinary.getAbsolutePath());
+      } else {
+        conf.set(YarnConfiguration.NM_GPU_PATH_TO_EXEC, getTestParentFolder());
+      }
     } catch (Exception e) {
       throw new RuntimeException("Failed to init fake binary", e);
     }
@@ -513,4 +524,18 @@ public class TestGpuDiscoverer {
 
     verify(gpuSpy, never()).getGpuDeviceInformation();
   }
+
+  @Test
+  public void testBinaryIsNotNvidiaSmi() throws YarnException {
+    exception.expect(YarnException.class);
+    exception.expectMessage(String.format(
+        "It should point to an %s binary, which is now %s",
+        "nvidia-smi", "badfile"));
+
+    Configuration conf = new Configuration(false);
+    setupFakeBinary(conf, "badfile", true);
+
+    GpuDiscoverer plugin = new GpuDiscoverer();
+    plugin.initialize(conf, binaryHelper);
+  }
 }