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* Updating no users thread to sleep 3 times longer when users are present

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to reduce the number of times thread wakes up.
* Updating startNoUsersThread to return if the thread is already running.
This commit is contained in:
Vitaliy Zakaznikov 2019-08-25 07:36:08 -04:00
parent 62988800e6
commit 2342d64d1b
1 changed files with 23 additions and 10 deletions
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33
dbms/src/Storages/LiveView/StorageLiveView.cpp
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@ -366,27 +366,40 @@ void StorageLiveView::checkTableCanBeDropped() const
void StorageLiveView::noUsersThread(std::shared_ptr<StorageLiveView> storage, const UInt64 & timeout) void StorageLiveView::noUsersThread(std::shared_ptr<StorageLiveView> storage, const UInt64 & timeout)
{ {
bool drop_table = false; bool drop_table = false;
UInt64 next_timeout = timeout;
if (storage->shutdown_called || storage->is_dropped) if (storage->shutdown_called)
return; return;
{ {
while (1) while (1)
{ {
std::unique_lock lock(storage->no_users_thread_mutex); std::unique_lock lock(storage->no_users_thread_mutex);
if(!storage->no_users_thread_condition.wait_for(lock, std::chrono::seconds(timeout), [&] { return storage->no_users_thread_wakeup; })) if (!storage->no_users_thread_condition.wait_for(lock, std::chrono::seconds(next_timeout), [&] { return storage->no_users_thread_wakeup; }))
{ {
storage->no_users_thread_wakeup = false; storage->no_users_thread_wakeup = false;
if (storage->shutdown_called || storage->is_dropped) if (storage->shutdown_called)
return; return;
if (storage->hasUsers()) if (storage->hasUsers())
{
/// Thread woke up but there are still users so sleep for 3 times longer than
/// the original timeout to reduce the number of times thread wakes up.
/// Wait until we are explicitely woken up when a user goes away to
/// reset wait time to the original timeout.
next_timeout = timeout * 3;
continue; continue;
}
if (!storage->global_context.getDependencies(storage->database_name, storage->table_name).empty()) if (!storage->global_context.getDependencies(storage->database_name, storage->table_name).empty())
continue; continue;
drop_table = true; drop_table = true;
} }
else { else
{
/// Thread was explicitly awaken so reset timeout to the original
next_timeout = timeout;
storage->no_users_thread_wakeup = false; storage->no_users_thread_wakeup = false;
if (storage->shutdown_called)
return;
continue; continue;
} }
break; break;
@ -421,12 +434,12 @@ void StorageLiveView::startNoUsersThread(const UInt64 & timeout)
{ {
if (no_users_thread.joinable()) if (no_users_thread.joinable())
{ {
{ /// If the thread is already running then
std::lock_guard lock(no_users_thread_mutex); /// wake it up and just return
no_users_thread_wakeup = true; std::lock_guard lock(no_users_thread_mutex);
no_users_thread_condition.notify_one(); no_users_thread_wakeup = true;
} no_users_thread_condition.notify_one();
no_users_thread.join(); return;
} }
{ {
std::lock_guard lock(no_users_thread_mutex); std::lock_guard lock(no_users_thread_mutex);