Threaded cURL. Consider experimental (what in this branch isn't?), however it drastically reduces hitching for me... so yup.

indra/llmessage/llcurl.cpp

@@ -620,11 +620,18 @@ void LLCurl::Easy::prepRequest(const std::string& url,
 
 ////////////////////////////////////////////////////////////////////////////
 
-class LLCurl::Multi
+class LLCurl::Multi : public LLThread
 {
 	LOG_CLASS(Multi);
 public:
 
+	typedef enum
+	{
+		PERFORM_STATE_READY=0,
+		PERFORM_STATE_PERFORMING=1,
+		PERFORM_STATE_COMPLETED=2
+	} ePerformState;
+
 	Multi();
 	~Multi();
 
@@ -634,13 +641,20 @@ public:
 	void removeEasy(Easy* easy);
 
 	S32 process();
-	S32 perform();
+	void perform();
+	
+	virtual void run();
 
 	CURLMsg* info_read(S32* msgs_in_queue);
 
 	S32 mQueued;
 	S32 mErrorCount;
 	
+	S32 mPerformState;
+
+	LLCondition* mSignal;
+	bool mQuitting;
+
 private:
 	void easyFree(Easy*);
 	
@@ -655,21 +669,32 @@ private:
 };
 
 LLCurl::Multi::Multi()
-	: mQueued(0),
-	  mErrorCount(0)
+	: LLThread("Curl Multi"),
+	  mQueued(0),
+	  mErrorCount(0),
+	  mPerformState(PERFORM_STATE_READY)
 {
+	mQuitting = false;
+	mSignal = new LLCondition;
+
 	mCurlMultiHandle = curl_multi_init();
 	if (!mCurlMultiHandle)
 	{
 		llwarns << "curl_multi_init() returned NULL! Easy handles: " << gCurlEasyCount << " Multi handles: " << gCurlMultiCount << llendl;
 		mCurlMultiHandle = curl_multi_init();
 	}
+	
 	llassert_always(mCurlMultiHandle);
 	++gCurlMultiCount;
 }
 
 LLCurl::Multi::~Multi()
 {
+	llassert(isStopped());
+
+	delete mSignal;
+	mSignal = NULL;
+
 	// Clean up active
 	for(easy_active_list_t::iterator iter = mEasyActiveList.begin();
 		iter != mEasyActiveList.end(); ++iter)
@@ -695,30 +720,50 @@ CURLMsg* LLCurl::Multi::info_read(S32* msgs_in_queue)
 	return curlmsg;
 }
 
-
-S32 LLCurl::Multi::perform()
+void LLCurl::Multi::perform()
 {
-	S32 q = 0;
-	for (S32 call_count = 0;
-		 call_count < MULTI_PERFORM_CALL_REPEAT;
-		 call_count += 1)
+	if (mPerformState == PERFORM_STATE_READY)
 	{
-		CURLMcode code = curl_multi_perform(mCurlMultiHandle, &q);
-		if (CURLM_CALL_MULTI_PERFORM != code || q == 0)
-		{
-			check_curl_multi_code(code);
-			break;
-		}
-	
+		mSignal->signal();
+	}
+}
+
+void LLCurl::Multi::run()
+{
+	while (!mQuitting)
+	{
+		mSignal->wait();
+		mPerformState = PERFORM_STATE_PERFORMING;
+		if (!mQuitting)
+		{
+			S32 q = 0;
+			for (S32 call_count = 0;
+				 call_count < MULTI_PERFORM_CALL_REPEAT;
+				 call_count += 1)
+			{
+				CURLMcode code = curl_multi_perform(mCurlMultiHandle, &q);
+				if (CURLM_CALL_MULTI_PERFORM != code || q == 0)
+				{
+					check_curl_multi_code(code);
+					break;
+				}
+	
+			}
+			mQueued = q;
+			mPerformState = PERFORM_STATE_COMPLETED;
+		}
 	}
-	mQueued = q;
-	return q;
 }
 
 S32 LLCurl::Multi::process()
 {
 	perform();
 
+	if (mPerformState != PERFORM_STATE_COMPLETED)
+	{
+		return 0;
+	}
+
 	CURLMsg* msg;
 	int msgs_in_queue;
 
@@ -749,6 +794,8 @@ S32 LLCurl::Multi::process()
 			}
 		}
 	}
+
+	mPerformState = PERFORM_STATE_READY;
 	return processed;
 }
 
@@ -827,6 +874,18 @@ LLCurlRequest::LLCurlRequest() :
 LLCurlRequest::~LLCurlRequest()
 {
 	llassert_always(mThreadID == LLThread::currentID());
+
+	//stop all Multi handle background threads
+	for (curlmulti_set_t::iterator iter = mMultiSet.begin(); iter != mMultiSet.end(); ++iter)
+	{
+		LLCurl::Multi* multi = *iter;
+		multi->mQuitting = true;
+		while (!multi->isStopped())
+		{
+			multi->mSignal->signal();
+			apr_sleep(1000);
+		}
+	}
 	for_each(mMultiSet.begin(), mMultiSet.end(), DeletePointer());
 }
 
@@ -834,6 +893,7 @@ void LLCurlRequest::addMulti()
 {
 	llassert_always(mThreadID == LLThread::currentID());
 	LLCurl::Multi* multi = new LLCurl::Multi();
+	multi->start();
 	mMultiSet.insert(multi);
 	mActiveMulti = multi;
 	mActiveRequestCount = 0;
@@ -963,6 +1023,13 @@ S32 LLCurlRequest::process()
 		if (multi != mActiveMulti && tres == 0 && multi->mQueued == 0)
 		{
 			mMultiSet.erase(curiter);
+			multi->mQuitting = true;
+			while (!multi->isStopped())
+			{
+				multi->mSignal->signal();
+				apr_sleep(1000);
+			}
+
 			delete multi;
 		}
 	}
@@ -993,6 +1060,7 @@ LLCurlEasyRequest::LLCurlEasyRequest()
 	  mResultReturned(false)
 {
 	mMulti = new LLCurl::Multi();
+	mMulti->start();
 	mEasy = mMulti->allocEasy();
 	if (mEasy)
 	{
@@ -1003,6 +1071,12 @@ LLCurlEasyRequest::LLCurlEasyRequest()
 
 LLCurlEasyRequest::~LLCurlEasyRequest()
 {
+	mMulti->mQuitting = true;
+	while (!mMulti->isStopped())
+	{
+		mMulti->mSignal->signal();
+		apr_sleep(1000);
+	}
 	delete mMulti;
 }
 	
@@ -1099,14 +1173,20 @@ void LLCurlEasyRequest::requestComplete()
 	}
 }
 
-S32 LLCurlEasyRequest::perform()
+void LLCurlEasyRequest::perform()
 {
-	return mMulti->perform();
+	mMulti->perform();
 }
 
 // Usage: Call getRestult until it returns false (no more messages)
 bool LLCurlEasyRequest::getResult(CURLcode* result, LLCurl::TransferInfo* info)
 {
+	if (mMulti->mPerformState != LLCurl::Multi::PERFORM_STATE_COMPLETED)
+	{ //we're busy, try again later
+		return false;
+	}
+	mMulti->mPerformState = LLCurl::Multi::PERFORM_STATE_READY;
+
 	if (!mEasy)
 	{
 		// Special case - we failed to initialize a curl_easy (can happen if too many open files)

indra/llmessage/llcurl.h

@@ -241,7 +241,7 @@ public:
 	void slist_append(const char* str);
 	void sendRequest(const std::string& url);
 	void requestComplete();
-	S32 perform();
+	void perform();
 	bool getResult(CURLcode* result, LLCurl::TransferInfo* info = NULL);
 	std::string getErrorString();
 

indra/newview/llxmlrpctransaction.cpp

@@ -319,16 +319,18 @@ bool LLXMLRPCTransaction::Impl::process()
 		}
 	}
 	
-	const F32 MAX_PROCESSING_TIME = 0.05f;
-	LLTimer timer;
+	//const F32 MAX_PROCESSING_TIME = 0.05f;
+	//LLTimer timer;
 
-	while (mCurlRequest->perform() > 0)
+	mCurlRequest->perform();
+
+	/*while (mCurlRequest->perform() > 0)
 	{
 		if (timer.getElapsedTimeF32() >= MAX_PROCESSING_TIME)
 		{
 			return false;
 		}
-	}
+	}*/
 
 	while(1)
 	{