Revert 86976 - Changed the ping count from 3 to 6, unresponsive count from 3 to 6.

Changed how often we send a ping from 2 secs to 1 sec. Changed check
for unresponsiveness time from 4 secs to 2 secs.

From jar: this change is to make it harder for scheduler to
a) grant time slices coursely; and 
b) favor the watchdog and disfavor the IO thread.

BUG=84145
TEST=thread watcher unit tests
R=jar
Review URL: http://codereview.chromium.org/6962033

TBR=rtenneti@chromium.org
Review URL: http://codereview.chromium.org/6962036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@86979 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 12 insertions, 15 deletions

diff --git a/chrome/browser/metrics/thread_watcher.cc b/chrome/browser/metrics/thread_watcher.cc
index 2b2ab3b..401c62a 100644
--- a/chrome/browser/metrics/thread_watcher.cc
+++ b/chrome/browser/metrics/thread_watcher.cc
@@ -13,10 +13,10 @@
 #endif
 
 // static
-const int ThreadWatcher::kPingCount = 6;
+const int ThreadWatcher::kPingCount = 3;
 
 // static
-const int ThreadWatcher::kUnresponsiveCount = 6;
+const int ThreadWatcher::kUnresponsiveCount = 3;
 
 // ThreadWatcher methods and members.
 ThreadWatcher::ThreadWatcher(const BrowserThread::ID& thread_id,
@@ -79,7 +79,6 @@ void ThreadWatcher::ActivateThreadWatching() {
   if (active_) return;
   active_ = true;
   ping_count_ = kPingCount;
-  ResetHangCounters();
   MessageLoop::current()->PostTask(
       FROM_HERE,
       method_factory_.NewRunnableMethod(&ThreadWatcher::PostPingMessage));
@@ -100,7 +99,6 @@ void ThreadWatcher::WakeUp() {
 
   if (ping_count_ <= 0) {
     ping_count_ = kPingCount;
-    ResetHangCounters();
     PostPingMessage();
   } else {
     ping_count_ = kPingCount;
@@ -180,7 +178,7 @@ bool ThreadWatcher::OnCheckResponsiveness(uint64 ping_sequence_number) {
   if (ping_sequence_number_ != ping_sequence_number) {
     // Reset unresponsive_count_ to zero because we got a response from the
     // watched thread.
-    ResetHangCounters();
+    GotGoodResponse();
     return true;
   }
   // Record that we got no response from watched thread.
@@ -235,7 +233,7 @@ void ThreadWatcher::OnPingMessage(const BrowserThread::ID& thread_id,
   WatchDogThread::PostTask(FROM_HERE, callback_task);
 }
 
-void ThreadWatcher::ResetHangCounters() {
+void ThreadWatcher::GotGoodResponse() {
   DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
   unresponsive_count_ = 0;
   hung_processing_complete_ = false;
@@ -245,7 +243,7 @@ void ThreadWatcher::GotNoResponse() {
   DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
 
   // Record how other threads are responding when we don't get a response for
-  // ping message atleast kUnresponsiveCount times.
+  // ping message atleast kUnresponsiveCount (three) times.
   if (++unresponsive_count_ < kUnresponsiveCount)
     return;
 
@@ -284,9 +282,9 @@ void ThreadWatcher::GotNoResponse() {
 // static
 ThreadWatcherList* ThreadWatcherList::global_ = NULL;
 // static
-const int ThreadWatcherList::kSleepSeconds = 1;
+const int ThreadWatcherList::kSleepSeconds = 2;
 // static
-const int ThreadWatcherList::kUnresponsiveSeconds = 2;
+const int ThreadWatcherList::kUnresponsiveSeconds = 4;
 
 ThreadWatcherList::ThreadWatcherList()
     : last_wakeup_time_(base::TimeTicks::Now()) {
@@ -422,7 +420,7 @@ void ThreadWatcherList::Observe(NotificationType type,
   base::TimeTicks now = base::TimeTicks::Now();
   {
     base::AutoLock lock(lock_);
-    if (now - last_wakeup_time_ > base::TimeDelta::FromSeconds(kSleepSeconds)) {
+    if (now - last_wakeup_time_ > base::TimeDelta::FromSeconds(2)) {
       need_to_awaken = true;
       last_wakeup_time_ = now;
     }
diff --git a/chrome/browser/metrics/thread_watcher.h b/chrome/browser/metrics/thread_watcher.h
index 5bfc90b..c4efd5f 100644
--- a/chrome/browser/metrics/thread_watcher.h
+++ b/chrome/browser/metrics/thread_watcher.h
@@ -133,7 +133,6 @@ class ThreadWatcher {
 
  private:
   friend class ThreadWatcherList;
-  friend class CustomThreadWatcher;
 
   // Allow tests to access our innards for testing purposes.
   FRIEND_TEST_ALL_PREFIXES(ThreadWatcherTest, Registration);
@@ -152,7 +151,7 @@ class ThreadWatcher {
 
   // This method resets unresponsive_count_ to zero because watched thread is
   // responding to the ping message with a pong message.
-  void ResetHangCounters();
+  void GotGoodResponse();
 
   // This method records watched thread is not responding to the ping message.
   // It increments unresponsive_count_ by 1.
@@ -226,7 +225,7 @@ class ThreadWatcher {
   int unresponsive_count_;
 
   // This is set to true when we would have crashed the browser because the
-  // watched thread hasn't responded atleast 6 times. It is reset to false when
+  // watched thread hasn't responded atleast 3 times. It is reset to false when
   // watched thread responds with a pong message.
   bool hung_processing_complete_;
 
diff --git a/chrome/browser/metrics/thread_watcher_unittest.cc b/chrome/browser/metrics/thread_watcher_unittest.cc
index c67aabf..0bc5f62 100644
--- a/chrome/browser/metrics/thread_watcher_unittest.cc
+++ b/chrome/browser/metrics/thread_watcher_unittest.cc
@@ -173,7 +173,7 @@ class CustomThreadWatcher : public ThreadWatcher {
     State exit_state;
     // Keep the thread that is running the tests waiting until ThreadWatcher
     // object's state changes to the expected_state or until wait_time elapses.
-    for (int i = 0; i < ThreadWatcher::kPingCount; ++i) {
+    for (int i = 0; i < 3; ++i) {
         TimeTicks end_time = TimeTicks::Now() + wait_time;
         {
           base::AutoLock auto_lock(custom_lock_);
@@ -202,7 +202,7 @@ class CustomThreadWatcher : public ThreadWatcher {
     // Keep the thread that is running the tests waiting until ThreadWatcher
     // object's check_response_state_ changes to the expected_state or until
     // wait_time elapses.
-    for (int i = 0; i < ThreadWatcher::kPingCount; ++i) {
+    for (int i = 0; i < 3; ++i) {
         TimeTicks end_time = TimeTicks::Now() + wait_time;
         {
           base::AutoLock auto_lock(custom_lock_);