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MXS-2196: Start listeners after worker threads

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If the startup of the listeners requires communication with all of the
workers, the workers must be up and running for that to happen.

Due to the fact that the main thread is still a worker thread, the
initialization code is not extra straightforward. By queuing an event to
the main worker, the startup of all listeners is done at a fully
operational state with all workers fully functional.

The service initialization code was also flawed in the sense that it would
cause a deadlock if any of the threads would have to check for the user
permissions. This is mainly a problem with the authenticator modules but
the benefits of the per service pre-loading of users is most likely
superficial. In theory startup will be faster as each thread now queries
the users in parallel.
This commit is contained in:
Markus Mäkelä
2018-12-02 11:21:49 +02:00
parent 015c581a5b
commit 7aa60b4a24
4 changed files with 42 additions and 50 deletions
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54
server/core/gateway.cc
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@ -1413,6 +1413,33 @@ int main(int argc, char** argv)
const char* specified_user = NULL;
char export_cnf[PATH_MAX + 1] = "";
/**
* The following lambda function is executed as the first event on the main worker. This is what starts
* up the listeners for all services.
*
* Due to the fact that the main thread runs a worker thread we have to queue the starting
* of the listeners to happen after all workers have started. This allows worker messages to be used
* when listeners are being started.
*
* Once the main worker is dedicated to doing work other than handling traffic the code could be executed
* immediately after the worker thread have been started. This would make the startup logic clearer as
* the order of the events would be the way they appear to be.
*/
auto do_startup = [&]() {
if (!service_launch_all())
{
const char* logerr = "Failed to start all MaxScale services. Exiting.";
print_log_n_stderr(true, true, logerr, logerr, 0);
rc = MAXSCALE_NOSERVICES;
RoutingWorker::shutdown_all();
}
else if (daemon_mode)
{
// Successful start, notify the parent process that it can exit.
write_child_exit_code(daemon_pipe[1], rc);
}
};
config_init();
config_set_global_defaults();
mxb_assert(cnf);
@ -2177,17 +2204,6 @@ int main(int argc, char** argv)
/** Start all monitors */
monitor_start_all();
/** Start the services that were created above */
n_services = service_launch_all();
if (n_services == -1)
{
const char* logerr = "Failed to start all MaxScale services. Exiting.";
print_log_n_stderr(true, true, logerr, logerr, 0);
rc = MAXSCALE_NOSERVICES;
goto return_main;
}
if (cnf->config_check)
{
MXS_NOTICE("Configuration was successfully verified.");
@ -2241,20 +2257,20 @@ int main(int argc, char** argv)
config_threadcount(),
config_thread_stack_size());
/**
* Successful start, notify the parent process that it can exit.
*/
mxb_assert(rc == MAXSCALE_SHUTDOWN);
if (daemon_mode)
worker = RoutingWorker::get(RoutingWorker::MAIN);
mxb_assert(worker);
if (!worker->execute(do_startup, RoutingWorker::EXECUTE_QUEUED))
{
write_child_exit_code(daemon_pipe[1], rc);
const char* logerr = "Failed to queue startup task.";
print_log_n_stderr(true, true, logerr, logerr, 0);
rc = MAXSCALE_INTERNALERROR;
goto return_main;
}
/*<
* Run worker 0 in the main thread.
*/
worker = RoutingWorker::get(RoutingWorker::MAIN);
mxb_assert(worker);
worker->run();
/** Stop administrative interface */