From 39dee8ea19172ad09cdc0f130545d6e6f8f7a67c Mon Sep 17 00:00:00 2001
From: zhihui wang <146961954+hiwangzhihui@users.noreply.github.com>
Date: Wed, 15 May 2024 03:03:49 +0800
Subject: [PATCH] HADOOP-18958.  Improve UserGroupInformation debug log.
 (#6255)

Contributed by zhihui wang
---
 .../hadoop/security/UserGroupInformation.java | 19 +++++++++++--------
 .../org/apache/hadoop/util/StringUtils.java   | 13 +++++++++++++
 .../apache/hadoop/util/TestStringUtils.java   |  9 +++++++++
 3 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java
index 07be1f8e54..305e5e10af 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java
@@ -88,6 +88,7 @@
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenIdentifier;
 import org.apache.hadoop.util.Shell;
+import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Time;
 
 import org.slf4j.Logger;
@@ -1934,10 +1935,7 @@ protected Subject getSubject() {
   @InterfaceAudience.Public
   @InterfaceStability.Evolving
   public <T> T doAs(PrivilegedAction<T> action) {
-    if (LOG.isDebugEnabled()) {
-      LOG.debug("PrivilegedAction [as: {}][action: {}]", this, action,
-          new Exception());
-    }
+    tracePrivilegedAction(action);
     return Subject.doAs(subject, action);
   }
   
@@ -1957,10 +1955,7 @@ public <T> T doAs(PrivilegedAction<T> action) {
   public <T> T doAs(PrivilegedExceptionAction<T> action
                     ) throws IOException, InterruptedException {
     try {
-      if (LOG.isDebugEnabled()) {
-        LOG.debug("PrivilegedAction [as: {}][action: {}]", this, action,
-            new Exception());
-      }
+      tracePrivilegedAction(action);
       return Subject.doAs(subject, action);
     } catch (PrivilegedActionException pae) {
       Throwable cause = pae.getCause();
@@ -1982,6 +1977,14 @@ public <T> T doAs(PrivilegedExceptionAction<T> action
     }
   }
 
+  private void tracePrivilegedAction(Object action) {
+    if (LOG.isTraceEnabled()) {
+      // would be nice if action included a descriptive toString()
+      LOG.trace("PrivilegedAction [as: {}][action: {}][from: {}]", this, action,
+          StringUtils.getStackTrace(new Throwable()));
+    }
+  }
+
   /**
    * Log current UGI and token information into specified log.
    * @param ugi - UGI
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java
index 2585729950..b109d8bacb 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringUtils.java
@@ -1148,6 +1148,19 @@ public static String getStackTrace(Thread t) {
     return str.toString();
   }
 
+  /**
+   * Get stack trace from throwable exception.
+   * @param t Throwable.
+   * @return stack trace string.
+   */
+  public static String getStackTrace(Throwable t) {
+    StringBuilder str = new StringBuilder();
+    for (StackTraceElement e : t.getStackTrace()) {
+      str.append(e.toString() + "\n\t");
+    }
+    return str.toString();
+  }
+
   /**
    * From a list of command-line arguments, remove both an option and the 
    * next argument.
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java
index c9b42b07f4..e6dcc5e8de 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringUtils.java
@@ -624,6 +624,15 @@ public void testStringCollectionSplitByEqualsFailure() throws Exception {
         () -> StringUtils.getTrimmedStringCollectionSplitByEquals(",="));
   }
 
+  @Test
+  public void testForGetStackTrace() {
+    Throwable throwable = new Throwable();
+    int stackLength = throwable.getStackTrace().length;
+    String stackTrace = StringUtils.getStackTrace(new Throwable());
+    String[] splitTrace = stackTrace.split("\n\t");
+    assertEquals(stackLength, splitTrace.length);
+  }
+
   // Benchmark for StringUtils split
   public static void main(String []args) {
     final String TO_SPLIT = "foo,bar,baz,blah,blah";