[webkit-changes] [92154] trunk/Source/JavaScriptCore

Mon, 01 Aug 2011 17:10:28 -0700

Title: [92154] trunk/Source/_javascript_Core
Revision
92154
Author
le...@chromium.org
Date
2011-08-01 17:10:21 -0700 (Mon, 01 Aug 2011)

Log Message

currentThread is too slow!
https://bugs.webkit.org/show_bug.cgi?id=64577

Reviewed by Darin Adler and Dmitry Titov.

The problem is that currentThread results in a pthread_once call which always takes a lock.
With this change, currentThread is 10% faster than isMainThread in release mode and only
5% slower than isMainThread in debug.

* wtf/ThreadIdentifierDataPthreads.cpp:
(WTF::ThreadIdentifierData::initializeOnce): Remove the pthread once stuff
which is no longer needed because this is called from initializeThreading().
(WTF::ThreadIdentifierData::identifier): Remove the initializeKeyOnce call because
intialization of the pthread key should already be done.
(WTF::ThreadIdentifierData::initialize): Ditto.
* wtf/ThreadIdentifierDataPthreads.h:
* wtf/ThreadingPthreads.cpp:
(WTF::initializeThreading): Acquire the pthread key here.

Modified Paths

Diff

Modified: trunk/Source/_javascript_Core/ChangeLog (92153 => 92154)


--- trunk/Source/_javascript_Core/ChangeLog	2011-08-02 00:07:14 UTC (rev 92153)
+++ trunk/Source/_javascript_Core/ChangeLog	2011-08-02 00:10:21 UTC (rev 92154)
@@ -1,3 +1,24 @@
+2011-07-14  David Levin  <le...@chromium.org>
+
+        currentThread is too slow!
+        https://bugs.webkit.org/show_bug.cgi?id=64577
+
+        Reviewed by Darin Adler and Dmitry Titov.
+
+        The problem is that currentThread results in a pthread_once call which always takes a lock.
+        With this change, currentThread is 10% faster than isMainThread in release mode and only
+        5% slower than isMainThread in debug.
+
+        * wtf/ThreadIdentifierDataPthreads.cpp:
+        (WTF::ThreadIdentifierData::initializeOnce): Remove the pthread once stuff
+        which is no longer needed because this is called from initializeThreading().
+        (WTF::ThreadIdentifierData::identifier): Remove the initializeKeyOnce call because
+        intialization of the pthread key should already be done.
+        (WTF::ThreadIdentifierData::initialize): Ditto.
+        * wtf/ThreadIdentifierDataPthreads.h:
+        * wtf/ThreadingPthreads.cpp:
+        (WTF::initializeThreading): Acquire the pthread key here.
+
 2011-08-01  Filip Pizlo  <fpi...@apple.com>
 
         DFG JIT sometimes creates speculation check data structures that have

Modified: trunk/Source/_javascript_Core/wtf/ThreadIdentifierDataPthreads.cpp (92153 => 92154)


--- trunk/Source/_javascript_Core/wtf/ThreadIdentifierDataPthreads.cpp	2011-08-02 00:07:14 UTC (rev 92153)
+++ trunk/Source/_javascript_Core/wtf/ThreadIdentifierDataPthreads.cpp	2011-08-02 00:10:21 UTC (rev 92154)
@@ -36,10 +36,11 @@
 
 #include "Threading.h"
 
+#include <limits.h>
+
 namespace WTF {
 
-pthread_key_t ThreadIdentifierData::m_key;
-static pthread_once_t _onceControl_ = PTHREAD_ONCE_INIT;
+pthread_key_t ThreadIdentifierData::m_key = PTHREAD_KEYS_MAX;
 
 void clearPthreadHandleForIdentifier(ThreadIdentifier);
 
@@ -48,9 +49,15 @@
     clearPthreadHandleForIdentifier(m_identifier);
 }
 
+void ThreadIdentifierData::initializeOnce()
+{
+    if (pthread_key_create(&m_key, destruct))
+        CRASH();
+}
+
 ThreadIdentifier ThreadIdentifierData::identifier()
 {
-    initializeKeyOnce();
+    ASSERT(m_key != PTHREAD_KEYS_MAX);
     ThreadIdentifierData* threadIdentifierData = static_cast<ThreadIdentifierData*>(pthread_getspecific(m_key));
 
     return threadIdentifierData ? threadIdentifierData->m_identifier : 0;
@@ -59,8 +66,6 @@
 void ThreadIdentifierData::initialize(ThreadIdentifier id)
 {
     ASSERT(!identifier());
-
-    initializeKeyOnce();
     pthread_setspecific(m_key, new ThreadIdentifierData(id));
 }
 
@@ -79,18 +84,6 @@
     pthread_setspecific(m_key, threadIdentifierData);
 }
 
-void ThreadIdentifierData::initializeKeyOnceHelper()
-{
-    if (pthread_key_create(&m_key, destruct))
-        CRASH();
-}
-
-void ThreadIdentifierData::initializeKeyOnce()
-{
-    if (pthread_once(&onceControl, initializeKeyOnceHelper))
-        CRASH();
-}
-
 } // namespace WTF
 
 #endif // USE(PTHREADS)

Modified: trunk/Source/_javascript_Core/wtf/ThreadIdentifierDataPthreads.h (92153 => 92154)


--- trunk/Source/_javascript_Core/wtf/ThreadIdentifierDataPthreads.h	2011-08-02 00:07:14 UTC (rev 92153)
+++ trunk/Source/_javascript_Core/wtf/ThreadIdentifierDataPthreads.h	2011-08-02 00:10:21 UTC (rev 92154)
@@ -42,6 +42,10 @@
 public:
     ~ThreadIdentifierData();
 
+    // One time initialization for this class as a whole.
+    // This method must be called before initialize() and it is not thread-safe.
+    static void initializeOnce();
+
     // Creates and puts an instance of ThreadIdentifierData into thread-specific storage.
     static void initialize(ThreadIdentifier identifier);
 
@@ -62,9 +66,6 @@
     // ThreadIdentifier from the threadMap, completing the cleanup.
     static void destruct(void* data);
 
-    static void initializeKeyOnceHelper();
-    static void initializeKeyOnce();
-
     ThreadIdentifier m_identifier;
     bool m_isDestroyedOnce;
     static pthread_key_t m_key;

Modified: trunk/Source/_javascript_Core/wtf/ThreadingPthreads.cpp (92153 => 92154)


--- trunk/Source/_javascript_Core/wtf/ThreadingPthreads.cpp	2011-08-02 00:07:14 UTC (rev 92153)
+++ trunk/Source/_javascript_Core/wtf/ThreadingPthreads.cpp	2011-08-02 00:10:21 UTC (rev 92154)
@@ -86,6 +86,7 @@
     atomicallyInitializedStaticMutex = new Mutex;
     threadMapMutex();
     initializeRandomNumberGenerator();
+    ThreadIdentifierData::initializeOnce();
     wtfThreadData();
 #if ENABLE(WTF_MULTIPLE_THREADS)
     s_dtoaP5Mutex = new Mutex;

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