Fix halt on 'PROXYSQL RESUME' command #4757
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During a RESUME operation, if a 'MySQL_Thread' is bootstrapping listeners (in `MySQL_Thread::run_BootstrapListener`) and detect that `MySQL_Threads_Handler::bootstrapping_listeners` is 'false', the thread prematurely shuts down its own bootstrapping flag from 'mypolls' (`ProxySQL_Poll::bootstrapping_listeners`). Since this thread wont ever bootstrap its corresponding listening sockets, the other working threads will be stalled waiting on it, eventually triggering the watchdog and crashing the instance. Since the bootstrapping operation is sequential, it's expected that all the threads but the one starting their listening sockets are in an active wait. A sensible delay has been introduced to reduce the overhead of such wait.
Since the operation of stopping each worker thread listeners is performed during 'maintenance_loops', the active wait taking place in 'listener_del' is likely to take some time. A sensible delay has been added to reduce unneccesary load.
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This is a follow-up of commit #19c8f8698
renecannao
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Nov 26, 2024
Fix halt on 'PROXYSQL RESUME' command - Port of #4757
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Issue Description
During a
RESUMEoperation, if a 'MySQL_Thread' is bootstrapping listeners (inMySQL_Thread::run_BootstrapListener) and detect thatMySQL_Threads_Handler::bootstrapping_listenersis 'false', the thread prematurely shuts down its own bootstrapping flag from 'mypolls' (ProxySQL_Poll::bootstrapping_listeners). Since this thread wont ever bootstrap its corresponding listening sockets, the other working threads will be stalled waiting on it, eventually triggering the watchdog and crashing the instance.Solution
Simplified the logic using a unique flag for bootstrapping (
MySQL_Threads_Handler::bootstrapping_listeners) and introduced a sensible delay to reduce the potential overhead of the worker threads busy-waiting for its time to start their listening sockets, as well as the counterpart overhead on theAdminthread while performing thePAUSEoperation.