Evgeny Kotkov <evgeny.kot...@visualsvn.com> writes: > (1) As a part of the process of shutting down worker threads, the code > around child.c:1170 currently posts an amount of I/O completion packets > equal to the amount of the threads blocked on the I/O completion port. > Then it sleeps until all these threads "acknowledge" the completion > packets by decrementing the global amount of blocked threads. > > This can be improved to avoid unnecessary Sleep()'s, and make the > shutdown faster. There is no need to block until the threads actually > receive the completion, as the shutdown process includes a separate step > that waits until the threads exit. Instead of synchronizing on the > amount of the threads blocked on the I/O completion port, we can send > the number of IOCP_SHUTDOWN completion packets equal to the total > amount of threads and immediately proceed to the next step.
Committed in https://svn.apache.org/r1801635 > (2) If the shutdown routine hits a timeout while waiting for the worker > threads to exit, it uses TerminateThread() to terminate the remaining > threads. > > Using TerminateThread() can have dangerous consequences such as > deadlocks — say, if the the thread is terminated while holding a lock > or a heap lock in the middle of HeapAlloc(), as these locks would not > be released. Or it can corrupt the application state and cause a crash. > See https://msdn.microsoft.com/en-us/library/windows/desktop/ms686717 > > Presumably, a much better alternative here would be to leave the cleanup > to the operating system by calling TerminateProcess(). Committed in https://svn.apache.org/r1801636 > (3) Assuming (2) is in place, the code around child.c:1170 that waits for > multiple thread handles in batches can be simplified. With (2), there > is no difference between ending the wait with one or multiple remaining > threads. (Since we terminate the process if at least one thread is > still active when we hit a timeout.) > > Therefore, instead of making an effort to evenly distribute and batch > the handles with WaitForMultipleObjects(), we could just start from > one end, and wait for one thread handle at a time. Committed in https://svn.apache.org/r1801637 Regards, Evgeny Kotkov
