If Tb is holding Rb, this will be like Ra->Ta->Rb->Tb, there is no deadlock. If Ta has acquired Ra, and is requiring Rb, this can be like a directed graph: Ra->Ta->Rb. Suppose system created 2 threads Ta and Tb, both Ta and Tb requires resource Ra and Rb. One method to detect deadlock is to construct a resource requirement graph for shared resources. Run application using nohup so that SIGHUP can be ignored.ĭeadlock detection can be done in higher level, for processes, deadlock detection can be done in Operating System level, for threads, the main thread could detect deadlock among sub-threads, if sub-threads don't require any system-level resources like I/O, etc.Can I detect deadlock through log? For example, on every wait/post, before sem_wait, log as going to wait, after sem_wait acquires the lock, waiting over and after sem_post (which is non blocking anyway), log as signal/post for waiting process - then if the program appears to hang, check the log to detect any cyclic waiting.The parent process (telnet session) gets timed out resulting in sending a SIGHUP signal to the child process.There is a deadlock, two threads are waiting on one another (cyclic waiting).The application seem to unresponsive while running for a longer time during processing of large volume of data. Synchronization semaphores – One thread waits calling sem_wait for some tasks to be done, other thread upon completion of the task, signals through sem_post.
#MYSQL DEADLOCK MULTITHREADED APPLICATION CODE#
Mutex semaphores – Critical section code under mutual exclusion between pthread_mutex_lock and pthread_mutex_unlock calls (done by same thread)
There are several semaphores that control the synchronization. threads get created through pthread_create. I am using multithreaded C++ application using posix threads i.e.
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