multithreading

问题 I am implementing multithreaded C++ program for Linux platform where I need a functionality similar to WaitForMultipleObjects(). While searching for the solution I observed that there are articles that describe how to achieve WaitForMultipleObjects() functionality in Linux with examples but those examples does not satisfy the scenario that I have to support. The scenario in my case is pretty simple. I have a daemon process in which the main thread exposes a method/callback to the outside

问题 I am using current_app.logger and when I tried to log inside thread it says "working outside of application context". How do I log a message from a method running in a thread? def background(): current_app.logger.debug('logged from thread') @app.route('/') def index(): Thread(target=background).start() return 'Hello, World!' Exception in thread Thread-16: Traceback (most recent call last): File "/usr/lib64/python3.5/threading.py", line 914, in _bootstrap_inner self.run() File "/usr/lib64

问题 I am using a Thread Group with Number Of Threads = 5 with an HTTP request. In the request I want to include a parameter with the value of the thread number, e.g., "pageno": ${threadno} I want to get the thread number like ${threadno} . How can I do that? 回答1: The thread number is available as: ${__threadNum} See: functions reference 回答2: While the above-mentioned ${__threadNum} will work in many places within jMeter, you'll need to use something else where it is not allowed, e.g., script

问题 Without doing in parallel programming I can merger left and right dataframe on key column using below code, but it will be too slow since both are very large. is there any way I can do it in parallelize efficiently ? I have 64 cores, and so practically I can use 63 of them to merge these two dataframe. left = pd.DataFrame({'key': ['K0', 'K1', 'K2', 'K3'], 'A': ['A0', 'A1', 'A2', 'A3'], 'B': ['B0', 'B1', 'B2', 'B3']}) right = pd.DataFrame({'key': ['K0', 'K1', 'K2', 'K3'], 'C': ['C0', 'C1', 'C2

问题 There is a shared_mutex class planned for C++17. And shared_timed_mutex already in C++14. (Who knows why they came in that order, but whatever.) Then there is a recursive_mutex and a recursive_timed_mutex since C++11. What I need is a shared_recursive_mutex . Did I miss something in the standard or do I have to wait another three years for a standardized version of that? If there is currently no such facility, what would be a simple (first priority) and efficient (2nd priority) implementation

问题 cppreference.com documents this function as "fence between a thread and a signal handler executed in the same thread". But I found no example on the Internet. I wonder whether or not the following psuedo-code correctly illustrates the function of std::atomic_signal_fence() : int n = 0; SignalObject s; void thread_1() { s.wait(); std::atomic_signal_fence(std::memory_order_acquire); assert(1 == n); // never fires ??? } void thread_2() { n = 1; s.signal(); } int main() { std::thread t1(thread_1)

问题 cppreference.com documents this function as "fence between a thread and a signal handler executed in the same thread". But I found no example on the Internet. I wonder whether or not the following psuedo-code correctly illustrates the function of std::atomic_signal_fence() : int n = 0; SignalObject s; void thread_1() { s.wait(); std::atomic_signal_fence(std::memory_order_acquire); assert(1 == n); // never fires ??? } void thread_2() { n = 1; s.signal(); } int main() { std::thread t1(thread_1)

问题 cppreference.com documents this function as "fence between a thread and a signal handler executed in the same thread". But I found no example on the Internet. I wonder whether or not the following psuedo-code correctly illustrates the function of std::atomic_signal_fence() : int n = 0; SignalObject s; void thread_1() { s.wait(); std::atomic_signal_fence(std::memory_order_acquire); assert(1 == n); // never fires ??? } void thread_2() { n = 1; s.signal(); } int main() { std::thread t1(thread_1)

问题 I have a restful micro service (web api) in .net 4.6.2 and I want to call a fire and forget function each time after certain endpoints are called to do some database cleanup work. I don' want to use Task.Run and I want to have a much reliable dedicated process to do this job. I found lot's of articles and discussions about how to use IhostedService in .net core for long running background tasks. https://docs.microsoft.com/en-us/dotnet/standard/microservices-architecture/multi-container

问题 The bounty expires in 2 days . Answers to this question are eligible for a +50 reputation bounty. Matt Robertson is looking for a canonical answer . I get an ANR-error in my Android app. The trace shows only one thread in blocked state (all the others are in state waiting, sleeping, native,..), so it doesn't seem to be in deadlock. There are two threads which I start (directly) manually, so I roughly know in which part of my app the ANR occurs. Unfortunately, I can't make any sense of the