From 23f6e69e374ce4a7fd0d45f633a3c9efcc8e8a07 Mon Sep 17 00:00:00 2001
From: Mathieu Chartier <mathieuc@google.com>
Date: Thu, 18 Dec 2014 18:24:39 -0800
Subject: Only dump suspend all histogram if we have samples

Helps fix gcstress ThreadStress.

Bug: 18576985
Change-Id: Ibebc0fed8a21e7b149f4b6e5154fb86deddcc68f
---
 runtime/thread_list.cc | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/runtime/thread_list.cc b/runtime/thread_list.cc
index 968e89d..9707c7b 100644
--- a/runtime/thread_list.cc
+++ b/runtime/thread_list.cc
@@ -101,9 +101,12 @@ void ThreadList::DumpNativeStacks(std::ostream& os) {
 void ThreadList::DumpForSigQuit(std::ostream& os) {
   {
     ScopedObjectAccess soa(Thread::Current());
-    Histogram<uint64_t>::CumulativeData data;
-    suspend_all_historam_.CreateHistogram(&data);
-    suspend_all_historam_.PrintConfidenceIntervals(os, 0.99, data);  // Dump time to suspend.
+    // Only print if we have samples.
+    if (suspend_all_historam_.SampleSize() > 0) {
+      Histogram<uint64_t>::CumulativeData data;
+      suspend_all_historam_.CreateHistogram(&data);
+      suspend_all_historam_.PrintConfidenceIntervals(os, 0.99, data);  // Dump time to suspend.
+    }
   }
   Dump(os);
   DumpUnattachedThreads(os);
-- 
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