I have trouble with specific boost::asio and boost::coroutine usage pattern.  I have a multi-thread application which uses boost::asio and boost::coroutine via its integration in boost::asio. Every thread has its own io_service object. The only shared state between threads are connection pools which are locked with mutex when connection is get or returned from/to the connection pool. When there is not enough connections in the pool I push infinite asio::steady_tiemer in internal structure of the pool and asynchronously waiting on it and I yielding from the couroutine function. When other thread returns connection to the pool it checks whether there is waiting timers, it gets waiting timer from the internal structure, it gets its io_service object and posts a lambda which wakes up the timer to resume the suspended coroutine. I have random crashes in the application. I try to investigate the problem with valgrind. It founds some issues but I cannot understand them because they happen in boost::coroutine and boost::asio internals. I posted two questions in stckoverflow with extract from my code and from valgrind and GDB output. The first link is with original question with extracts from my source and the second one contains proof of concept application aimed to investigate the problem in isolation. Can someone help me explaining what is my mistake which causes those problems?