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Merge pull request #15763 from ClickHouse/fix_race_condition_in_mysql_pool

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Fix race condition in MySQL pool
This commit is contained in:
alesapin 2020-10-09 09:43:25 +03:00 committed by GitHub
commit 66b7748b63
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4 changed files with 23 additions and 10 deletions
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14
base/mysqlxx/Pool.cpp
View File

@ -21,8 +21,8 @@ void Pool::Entry::incrementRefCount()
{
if (!data)
return;
++data->ref_count;
if (data->ref_count == 1)
/// First reference, initialize thread
if (data->ref_count.fetch_add(1) == 0)
mysql_thread_init();
}
@ -30,12 +30,10 @@ void Pool::Entry::decrementRefCount()
{
if (!data)
return;
if (data->ref_count > 0)
{
--data->ref_count;
if (data->ref_count == 0)
mysql_thread_end();
}
/// We were the last user of this thread, deinitialize it
if (data->ref_count.fetch_sub(1) == 1)
mysql_thread_end();
}

5
base/mysqlxx/Pool.h
View File

@ -3,6 +3,7 @@
#include <list>
#include <memory>
#include <mutex>
#include <atomic>
#include <Poco/Exception.h>
#include <mysqlxx/Connection.h>
@ -35,7 +36,9 @@ protected:
struct Connection
{
mysqlxx::Connection conn;
int ref_count = 0;
/// Ref count modified in constructor/descructor of Entry
/// but also read in pool code.
std::atomic<int> ref_count = 0;
};
public:

12
tests/integration/test_dictionaries_mysql/configs/log_conf.xml Normal file
View File

@ -0,0 +1,12 @@
<?xml version="1.0" encoding="utf-8"?>
<yandex>
<logger>
<level>trace</level>
<log>/var/log/clickhouse-server/log.log</log>
<errorlog>/var/log/clickhouse-server/log.err.log</errorlog>
<size>1000M</size>
<count>10</count>
<stderr>/var/log/clickhouse-server/stderr.log</stderr>
<stdout>/var/log/clickhouse-server/stdout.log</stdout>
</logger>
</yandex>

2
tests/integration/test_dictionaries_mysql/test.py
View File

@ -5,7 +5,7 @@ from helpers.cluster import ClickHouseCluster
CONFIG_FILES = ['configs/dictionaries/mysql_dict1.xml', 'configs/dictionaries/mysql_dict2.xml',
'configs/remote_servers.xml']
CONFIG_FILES += ['configs/enable_dictionaries.xml']
CONFIG_FILES += ['configs/enable_dictionaries.xml', 'configs/log_conf.xml']
cluster = ClickHouseCluster(__file__)
instance = cluster.add_instance('instance', main_configs=CONFIG_FILES, with_mysql=True)