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core: make sure we don't throttle change signal generator when a reload is pending

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Fixes: #10627
This commit is contained in:
Lennart Poettering 2018-11-13 12:48:49 +01:00
parent 4b66bccab0
commit b8d381c477
1 changed files with 39 additions and 25 deletions
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64
src/core/manager.c
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@ -2157,56 +2157,70 @@ static unsigned manager_dispatch_dbus_queue(Manager *m) {
assert(m);
/* Avoid recursion */
if (m->dispatching_dbus_queue)
return 0;
/* Anything to do at all? */
if (!m->dbus_unit_queue && !m->dbus_job_queue && !m->send_reloading_done && !m->pending_reload_message)
return 0;
/* When we are reloading, let's not wait with generating signals, since we need to exit the manager as quickly
* as we can. There's no point in throttling generation of signals in that case. */
if (MANAGER_IS_RELOADING(m) || m->send_reloading_done || m->pending_reload_message)
budget = (unsigned) -1; /* infinite budget in this case */
else {
/* Anything to do at all? */
if (!m->dbus_unit_queue && !m->dbus_job_queue)
return 0;
/* Do we have overly many messages queued at the moment? If so, let's not enqueue more on top, let's sit this
* cycle out, and process things in a later cycle when the queues got a bit emptier. */
if (manager_bus_n_queued_write(m) > MANAGER_BUS_BUSY_THRESHOLD)
return 0;
/* Do we have overly many messages queued at the moment? If so, let's not enqueue more on top, let's
* sit this cycle out, and process things in a later cycle when the queues got a bit emptier. */
if (manager_bus_n_queued_write(m) > MANAGER_BUS_BUSY_THRESHOLD)
return 0;
/* Only process a certain number of units/jobs per event loop iteration. Even if the bus queue wasn't overly
* full before this call we shouldn't increase it in size too wildly in one step, and we shouldn't monopolize
* CPU time with generating these messages. Note the difference in counting of this "budget" and the
* "threshold" above: the "budget" is decreased only once per generated message, regardless how many
* busses/direct connections it is enqueued on, while the "threshold" is applied to each queued instance of bus
* message, i.e. if the same message is enqueued to five busses/direct connections it will be counted five
* times. This difference in counting ("references" vs. "instances") is primarily a result of the fact that
* it's easier to implement it this way, however it also reflects the thinking that the "threshold" should put
* a limit on used queue memory, i.e. space, while the "budget" should put a limit on time. Also note that
* the "threshold" is currently chosen much higher than the "budget". */
budget = MANAGER_BUS_MESSAGE_BUDGET;
/* Only process a certain number of units/jobs per event loop iteration. Even if the bus queue wasn't
* overly full before this call we shouldn't increase it in size too wildly in one step, and we
* shouldn't monopolize CPU time with generating these messages. Note the difference in counting of
* this "budget" and the "threshold" above: the "budget" is decreased only once per generated message,
* regardless how many busses/direct connections it is enqueued on, while the "threshold" is applied to
* each queued instance of bus message, i.e. if the same message is enqueued to five busses/direct
* connections it will be counted five times. This difference in counting ("references"
* vs. "instances") is primarily a result of the fact that it's easier to implement it this way,
* however it also reflects the thinking that the "threshold" should put a limit on used queue memory,
* i.e. space, while the "budget" should put a limit on time. Also note that the "threshold" is
* currently chosen much higher than the "budget". */
budget = MANAGER_BUS_MESSAGE_BUDGET;
}
m->dispatching_dbus_queue = true;
while (budget > 0 && (u = m->dbus_unit_queue)) {
while (budget != 0 && (u = m->dbus_unit_queue)) {
assert(u->in_dbus_queue);
bus_unit_send_change_signal(u);
n++, budget--;
n++;
if (budget != (unsigned) -1)
budget--;
}
while (budget > 0 && (j = m->dbus_job_queue)) {
while (budget != 0 && (j = m->dbus_job_queue)) {
assert(j->in_dbus_queue);
bus_job_send_change_signal(j);
n++, budget--;
n++;
if (budget != (unsigned) -1)
budget--;
}
m->dispatching_dbus_queue = false;
if (budget > 0 && m->send_reloading_done) {
if (m->send_reloading_done) {
m->send_reloading_done = false;
bus_manager_send_reloading(m, false);
n++, budget--;
n++;
}
if (budget > 0 && m->pending_reload_message) {
if (m->pending_reload_message) {
bus_send_pending_reload_message(m);
n++;
}