【发布时间】：2014-10-23 11:12:25
【问题描述】：
这是thread 的后续问题。
我传递了一个结构...
struct threadDirectives_t {
int block;
medianfilter mFilter;
};
...我线程的方法computeSignalBlock。但是，它不输出任何文本。既不是cout，也不是printf。
我只得到这个控制台输出：
Start computing filtered results.
Started thread 0.
Started thread 1.
这是为什么呢？
void medianfilter::computeFilteredResults(vector<float> _signals, int _nThreads,
int _windowSize, bool _isParallel) {
printf("Start computing filtered results.\n");
// Set instanz variables.
originalSignalVector = _signals;
nThreads = _nThreads;
windowSize = _windowSize;
isParallel = _isParallel;
// Create the threads,
pthread_t threads[nThreads];
threadDirectives_t threadDirectivesArr[nThreads];
pthread_attr_t attr;
// Initialize and set thread joinable
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
int threatResponse;
for (int i = 0; i < nThreads; i++) {
threadDirectives_t iTD;
iTD.block = i;
iTD.mFilter = *this;
threadDirectivesArr[i] = iTD;
threatResponse = pthread_create(&threads[i], NULL, computeSignalBlock,
(void *) &threadDirectivesArr[i]);
if (threatResponse) {
printf("Error: unable to create thread: %d\n", threatResponse);
exit(-1);
}
printf("Started thread %d.\n", i);
}
}
void *medianfilter::computeSignalBlock(void *threadDirectives) {
threadDirectives_t* thisPtr =
reinterpret_cast<threadDirectives_t*>(threadDirectives);
cout << "test";
//TODO I need access to instance variables!!
// 1) Get my block to compute.
printf("This is computation block # %d\n", thisPtr->block);
// 2) Compute block.
}
项目构建完成并出现警告。
12:55:39 **** Incremental Build of configuration Debug for project SSExercise3 ****
make all
Building file: ../src/medianfilter.cpp
Invoking: GCC C++ Compiler
g++ -std=c++0x -O0 -g3 -Wall -c -fmessage-length=0 -pthread -MMD -MP -MF"src/medianfilter.d" -MT"src/medianfilter.d" -o "src/medianfilter.o" "../src/medianfilter.cpp"
../src/medianfilter.cpp: In static member function ‘static void* medianfilter::computeSignalBlock(void*)’:
../src/medianfilter.cpp:79:1: warning: no return statement in function returning non-void [-Wreturn-type]
}
^
Finished building: ../src/medianfilter.cpp
Building target: SSExercise3
Invoking: GCC C++ Linker
g++ -pthread -o "SSExercise3" ./src/SSExercise3.o ./src/medianfilter.o ./src/reader.o
Finished building target: SSExercise3
12:55:40 Build Finished (took 1s.204ms)
我错过了什么？
【问题讨论】：
-
由于您使用的是 C++11，请考虑使用 std::thread。
-
警告文本说得很好：
medianfilter::computeSignalBlock中没有声明返回指向 void 的指针的 return 语句。 -
您可能需要
pthread_join，因为其他程序在未完成线程作业的情况下终止。 -
在@AlexeyKukanov 发表评论后，您可能应该编辑您的代码，然后在重新编译后与我们分享您的结果。
-
@sfrehse 是的，等待失败。请张贴作为答案，我会接受。感谢大家的额外提示！
标签： c++ multithreading