经过两个多月的攻关，终于搞定了live555多线程并稳定压测通过

本文主要是介绍经过两个多月的攻关，终于搞定了live555多线程并稳定压测通过，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

live555已经发展了十几年了，不得不钦佩作者坚持不懈的奉献和国外的开源生态环境，live555可以说是大部分的安防从业者的入门之选，尤其是在嵌入式或者Linux系统上，其应用还是蛮广泛的，主要是其兼容性和稳定性；

live555多线程

但是随着live555十几年的不断迭代，很多开发者反复向作者Ross提到的多线程和IPv6的功能，作者也一直都没有去尝试，可能是这样会对live555的架构产生比较大的改动和影响，作者为了稳妥，选择了小改动、稳定、逐步迭代的方式, 虽然是性能稳定，但支持的路数有限，不能多线程工作始终是个坎; 网上找到几篇live555多线程的博客, 基本上大同小异，就是创建独立的UsageEnvironment和TaskSchedule, 由独立的线程分工协作; 本人也是这个思路,创建多个工作线程,每个工作线程内创建UsageEnvironment和TaskSchedule,然后各自开启EventLoop;

今天我们抛砖引玉，先大概聊一下主体思路，在后续的博客中将尽力完整地汇总这些思路和开发的过程：

目标

将live555修改为多线程, 每个通道对应一个工作线程,由工作线程对该通道进行独立处理;

大体修改点

修改支持多线程, 主要涉及到以下类的修改

GenericMediaServer
RTSPServer

GenericMediaServer.cpp
在GenericMediaServer的构造函数中, 创建工作线程个数,即最大支持的通道数;

GenericMediaServer
::GenericMediaServer(UsageEnvironment& env, int ourSocketV4, int ourSocketV6, Port ourPort,unsigned reclamationSeconds): Medium(env),fServerSocket4(ourSocketV4), fServerSocket6(ourSocketV6), fServerPort(ourPort), fReclamationSeconds(reclamationSeconds),fServerMediaSessions(HashTable::create(STRING_HASH_KEYS)),fClientConnections(HashTable::create(ONE_WORD_HASH_KEYS)),fClientSessions(HashTable::create(STRING_HASH_KEYS)) {ignoreSigPipeOnSocket(fServerSocket4); // so that clients on the same host that are killed don't also kill usignoreSigPipeOnSocket(fServerSocket6); // so that clients on the same host that are killed don't also kill us#ifdef LIVE_MULTI_THREAD_ENABLEInitMutex(&mutexClientConnection);memset(&multiThreadCore, 0x00, sizeof(MultiThread_CORE_T));multiThreadCore.threadNum = MAX_DEFAULT_MULTI_THREAD_NUM;multiThreadCore.threadTask = new LIVE_THREAD_TASK_T[multiThreadCore.threadNum];memset(&multiThreadCore.threadTask[0], 0x00, sizeof(LIVE_THREAD_TASK_T) * multiThreadCore.threadNum);for (int i=0; i<multiThreadCore.threadNum; i++){char szName[36] = {0};sprintf(szName, "worker thread %d", i);multiThreadCore.threadTask[i].id = i;multiThreadCore.threadTask[i].extPtr = this;multiThreadCore.threadTask[i].pSubScheduler = BasicTaskScheduler::createNew();multiThreadCore.threadTask[i].pSubEnv = BasicUsageEnvironment::createNew(*multiThreadCore.threadTask[i].pSubScheduler, i+1, szName);CreateOSThread( &multiThreadCore.threadTask[i].osThread, __OSThread_Proc, (void *)&multiThreadCore.threadTask[i] );}
#endif// Arrange to handle connections from others:env.taskScheduler().turnOnBackgroundReadHandling(fServerSocket4, incomingConnectionHandler4, this);env.taskScheduler().turnOnBackgroundReadHandling(fServerSocket6, incomingConnectionHandler6, this);
}

接受客户端连接

按原有流程接受客户端连接;

分配客户端请求

在收到客户端发送的DESCRIBE命令后,
在通道列表中找出空闲的通道，将该客户端关联到该通道, 然后从主线程中移除该socket, 由工作线程接管该socket的操作;
后续有客户端如访问已经存在的通道,则主线程会将该请求直接分配给对应的工作线程处理;

注意: 主线程的工作到此结束，不要执行lookupServerMediaSession的操作;

在工作线程中, 接管客户端的socket后, 马上执行lookupServerMediaSession, 在该函数中，将后缀回调给上层调用程序, 由上层调用程序判断是否存在该通道，如不存在则返回失败，如存在则向前端取流，然后填充媒体信息返回成功, 库内部则创建相应的mediasession, 再回应客户端, 后续的则完成整个rtsp流程的交互;

注意: 创建MediaSession时，必须将工作线程中的UsageEnvironment传进去, 不能使用主线程中的envir();

int RTSPServer::RTSPClientConnection
::handleCmd_DESCRIBE(UsageEnvironment *pEnv, char const* urlPreSuffix, char const* urlSuffix, char const* fullRequestStr, LIVE_THREAD_TASK_T **pThreadTask) 
{int handleCmdRet = 0;ServerMediaSession* session = NULL;char* sdpDescription = NULL;char* rtspURL = NULL;do {char urlTotalSuffix[2*RTSP_PARAM_STRING_MAX];// enough space for urlPreSuffix/urlSuffix'\0'urlTotalSuffix[0] = '\0';if (urlPreSuffix[0] != '\0') {strcat(urlTotalSuffix, urlPreSuffix);strcat(urlTotalSuffix, "/");}strcat(urlTotalSuffix, urlSuffix);if (!authenticationOK("DESCRIBE", urlTotalSuffix, fullRequestStr)) break;// We should really check that the request contains an "Accept:" #####// for "application/sdp", because that's what we're sending back #####_TRACE(TRACE_LOG_DEBUG, "handleCmd_DESCRIBE  socket[%d]\n", this->fOurSocket);#ifdef LIVE_MULTI_THREAD_ENABLE//如果当前是主线程,则进入到查找通道流程if (pEnv->GetEnvirId() == 1000){fOurServer.LockClientConnection();  //LockUsageEnvironment  *pChEnv = fOurServer.GetEnvBySuffix(urlSuffix, this, pThreadTask);if (NULL == pChEnv){fOurServer.UnlockClientConnection();        //UnlockhandleCmdRet = -1;this->assignSink = False;this->pEnv = NULL;handleCmd_notFound();break;}else{_TRACE(TRACE_LOG_DEBUG, "将socket[%d] 关联到[%s]\n", this->fOurSocket, pChEnv->GetEnvirName());//将socket从主线程移到工作线程中UsageEnvironment  *pMainEnv = &envir();envir().taskScheduler().disableBackgroundHandling(fOurSocket);fOurServer.UnlockClientConnection();        //Unlockreturn 1000;}break;}#endif// Begin by looking up the "ServerMediaSession" object for the specified "urlTotalSuffix"://在工作线程中执行 lookupServerMediaSessionsession = fOurServer.lookupServerMediaSession(pEnv, 1, this, urlTotalSuffix);if (session == NULL) {//pChEnv->taskScheduler().disableBackgroundHandling(fOurSocket);_TRACE(TRACE_LOG_DEBUG, "socket[%d] 在[%s]中, 源未就绪[%s]\n", this->fOurSocket, pEnv->GetEnvirName(), urlTotalSuffix);this->assignSink = False;this->pEnv = NULL;handleCmdRet = -1;//envir().taskScheduler().disableBackgroundHandling(fOurSocket);//fOurServer.ResetEnvBySuffix(urlSuffix, this);handleCmd_notFound();break;}session->incrementReferenceCount();// Then, assemble a SDP description for this session:sdpDescription = session->generateSDPDescription(fOurIPVer);if (sdpDescription == NULL) {// This usually means that a file name that was specified for a// "ServerMediaSubsession" does not exist.setRTSPResponse("404 File Not Found, Or In Incorrect Format");break;}unsigned sdpDescriptionSize = strlen(sdpDescription);// Also, generate our RTSP URL, for the "Content-Base:" header// (which is necessary to ensure that the correct URL gets used in subsequent "SETUP" requests).rtspURL = fOurRTSPServer.rtspURL(session, fOurIPVer, fClientInputSocket);snprintf((char*)fResponseBuffer, sizeof fResponseBuffer,"RTSP/1.0 200 OK\r\nCSeq: %s\r\n""%s""Content-Base: %s/\r\n""Content-Type: application/sdp\r\n""Content-Length: %d\r\n\r\n""%s",fCurrentCSeq,dateHeader(),rtspURL,sdpDescriptionSize,sdpDescription);} while (0);if (session != NULL) {// Decrement its reference count, now that we're done using it:session->decrementReferenceCount();if (session->referenceCount() == 0 && session->deleteWhenUnreferenced()) {fOurServer.removeServerMediaSession(pEnv, session, True);}session->SetStreamStatus(1);        //置标志,让后续访问该通道的客户端可以得到迅速响应}delete[] sdpDescription;delete[] rtspURL;return handleCmdRet;
}

历经2个多月，终于将多线程问题搞定. 在此记录一下, 欢迎探讨;

目前用户测试反馈的情况是：