mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-10 15:43:23 +02:00
da07a1e856
Background workers are postmaster subprocesses that run arbitrary user-specified code. They can request shared memory access as well as backend database connections; or they can just use plain libpq frontend database connections. Modules listed in shared_preload_libraries can register background workers in their _PG_init() function; this is early enough that it's not necessary to provide an extra GUC option, because the necessary extra resources can be allocated early on. Modules can install more than one bgworker, if necessary. Care is taken that these extra processes do not interfere with other postmaster tasks: only one such process is started on each ServerLoop iteration. This means a large number of them could be waiting to be started up and postmaster is still able to quickly service external connection requests. Also, shutdown sequence should not be impacted by a worker process that's reasonably well behaved (i.e. promptly responds to termination signals.) The current implementation lets worker processes specify their start time, i.e. at what point in the server startup process they are to be started: right after postmaster start (in which case they mustn't ask for shared memory access), when consistent state has been reached (useful during recovery in a HOT standby server), or when recovery has terminated (i.e. when normal backends are allowed). In case of a bgworker crash, actions to take depend on registration data: if shared memory was requested, then all other connections are taken down (as well as other bgworkers), just like it were a regular backend crashing. The bgworker itself is restarted, too, within a configurable timeframe (which can be configured to be never). More features to add to this framework can be imagined without much effort, and have been discussed, but this seems good enough as a useful unit already. An elementary sample module is supplied. Author: Álvaro Herrera This patch is loosely based on prior patches submitted by KaiGai Kohei, and unsubmitted code by Simon Riggs. Reviewed by: KaiGai Kohei, Markus Wanner, Andres Freund, Heikki Linnakangas, Simon Riggs, Amit Kapila |
||
|---|---|---|
| .. | ||
| adminpack | ||
| auth_delay | ||
| auto_explain | ||
| btree_gin | ||
| btree_gist | ||
| chkpass | ||
| citext | ||
| cube | ||
| dblink | ||
| dict_int | ||
| dict_xsyn | ||
| dummy_seclabel | ||
| earthdistance | ||
| file_fdw | ||
| fuzzystrmatch | ||
| hstore | ||
| intagg | ||
| intarray | ||
| isn | ||
| lo | ||
| ltree | ||
| oid2name | ||
| pageinspect | ||
| passwordcheck | ||
| pg_archivecleanup | ||
| pg_buffercache | ||
| pg_freespacemap | ||
| pg_standby | ||
| pg_stat_statements | ||
| pg_test_fsync | ||
| pg_test_timing | ||
| pg_trgm | ||
| pg_upgrade | ||
| pg_upgrade_support | ||
| pgbench | ||
| pgcrypto | ||
| pgrowlocks | ||
| pgstattuple | ||
| seg | ||
| sepgsql | ||
| spi | ||
| sslinfo | ||
| start-scripts | ||
| tablefunc | ||
| tcn | ||
| test_parser | ||
| tsearch2 | ||
| unaccent | ||
| uuid-ossp | ||
| vacuumlo | ||
| worker_spi | ||
| xml2 | ||
| contrib-global.mk | ||
| Makefile | ||
| README | ||
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "gmake all" and "gmake
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.