libunwind is reentrant and signal safe, and works faster then then
gcc_eh (plus it has some custom patches for problems that have been
found during it's usage in ClickHouse).
gcc_eh may be missing in the system (if gcc was not installed), and
even if it exists clickhouse uses -nodefaultlibs, so some care should be
made to make it work.
Also this library is tiny and there shouln't be any problem to require
it always (there is already tendency to require some contrib libraries,
i.e. poco).
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
While I was investigating some issues, I noticed that messages from
table startup are not appears in system.text_log due to too late
initialization.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
In case of it is terminated forcefully it will not be terminated
gracefully (i.e. run dtors and stuff), and by using warning log level
those messages will go to clickhouse-server.err.log, in which messages
are kept for a longer period then in clickhouse-server.log (at least
because it contains only warnings, errors and fatals only).
This will help with investigating some obscure issues.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
After #36425 there was a lot of confusions/problems with configuring pools - when the message was confusing, and settings need to be ajusted in several places.
See some examples in #44251, #43351, #47900, #46515.
The commit includes the following changes:
1) Introduced a unified mechanism for reading pool sizes from the configuration file(s). Previously, pool sizes were read from the Context.cpp with fallbacks to profiles, whereas main_config_reloader in Server.cpp read them directly without fallbacks.
2) Corrected the data type for background_merges_mutations_concurrency_ratio. It should be float instead of int.
3) Refactored the default values for settings. Previously, they were defined in multiple places throughout the codebase, but they are now defined in one place (or two, to be exact: Settings.h and ServerSettings.h).
4) Improved documentation, including the correct message in system.settings.
Additionally make the code more conform with #46550.
