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ClickHouse® is a real-time analytics DBMS
f15a5461be
If you will execute 'SYSTEM RELOAD CONFIG' via, i.e., TCP protocol, then
reload on port change will endlessly wait for connection from which this
query had been issued, and you will see the following message in the
logs:
2022.04.28 03:34:57.552513 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Debug> executeQuery: (from 127.0.0.1:11774) system reload config
...
2022.04.28 03:34:57.710640 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Information> Application: Stopped listening for http://127.0.0.1:18123
2022.04.28 03:34:57.798774 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Information> Application: Stopped listening for native protocol (tcp): 127.0.0.1:19000
...
2022.04.28 03:34:57.901375 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Debug> Application: Server finished: http://127.0.0.1:18123
2022.04.28 03:34:57.901455 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Trace> Application: Waiting server to finish: native protocol (tcp): 127.0.0.1:19000
2022.04.28 03:34:58.001717 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Trace> Application: Waiting server to finish: native protocol (tcp): 127.0.0.1:19000
2022.04.28 03:34:58.101881 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Trace> Application: Waiting server to finish: native protocol (tcp): 127.0.0.1:19000
...
2022.04.28 03:35:01.707951 [ 37101 ] {b41d855c-4dbf-470a-a144-c6ae5a1abda8} <Trace> Application: Waiting server to finish: native protocol (tcp): 127.0.0.1:19000
But waiting for the current connection will never ends.
So instead of waiting directly from the query context (SYSTEM RELOAD
CONFIG) do this in background (actually not even in background, but
check on server reload and on exit).
v0: just don't wait for the servers
v2: fix use-after-free by removing dependency from server in handlers
v3: wait servers in background to avoid use-after-free of the context
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
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| tests | ||
| tools/clickhouse-diagnostics | ||
| utils | ||
| website | ||
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| .gitattributes | ||
| .gitignore | ||
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| .pylintrc | ||
| .vimrc | ||
| .yamllint | ||
| AUTHORS | ||
| CHANGELOG.md | ||
| CMakeLists.txt | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| format_sources | ||
| LICENSE | ||
| PreLoad.cmake | ||
| README.md | ||
| SECURITY.md | ||
ClickHouse® is an open-source column-oriented database management system that allows generating analytical data reports in real-time.
Useful Links
- Official website has a quick high-level overview of ClickHouse on the main page.
- Tutorial shows how to set up and query a small ClickHouse cluster.
- Documentation provides more in-depth information.
- YouTube channel has a lot of content about ClickHouse in video format.
- Slack and Telegram allow chatting with ClickHouse users in real-time.
- Blog contains various ClickHouse-related articles, as well as announcements and reports about events.
- Code Browser (Woboq) with syntax highlight and navigation.
- Code Browser (github.dev) with syntax highlight, powered by github.dev.
- Contacts can help to get your questions answered if there are any.