HADOOP-13458. LoadBalancingKMSClientProvider#doOp should log IOException stacktrace. Contributed by Chen Liang.

(cherry picked from commit a1f6564d31c16582ea949e4448091f1cc56c7dfe)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/key/kms/LoadBalancingKMSClientProvider.java

@@ -33,6 +33,7 @@ import org.apache.hadoop.crypto.key.KeyProviderCryptoExtension.EncryptedKeyVersi
 import org.apache.hadoop.crypto.key.KeyProviderDelegationTokenExtension;
 import org.apache.hadoop.security.Credentials;
 import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Time;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -93,8 +94,8 @@ public class LoadBalancingKMSClientProvider extends KeyProvider implements
       try {
         return op.call(provider);
       } catch (IOException ioe) {
-        LOG.warn("KMS provider at [{}] threw an IOException [{}]!!",
-            provider.getKMSUrl(), ioe.getMessage());
+        LOG.warn("KMS provider at [{}] threw an IOException!! {}",
+            provider.getKMSUrl(), StringUtils.stringifyException(ioe));
         ex = ioe;
       } catch (Exception e) {
         if (e instanceof RuntimeException) {