mirror of https://github.com/postgres/postgres
Background workers gain a new flag, called BGWORKER_INTERRUPTIBLE, that offers the possibility to terminate the workers when these are connected to a database that is involved in one of the following commands: ALTER DATABASE RENAME TO ALTER DATABASE SET TABLESPACE CREATE DATABASE DROP DATABASE This is useful to give background workers the same behavior as backends and autovacuum workers, which are stopped when these commands are executed. The default behavior, that exists since 9.3, is still to never terminate bgworkers connected to the database involved in any of these commands. The new flag has to be set to terminate the workers. A couple of tests are added to worker_spi to track the commands that impact the termination of the workers. There is a test case for a non-interruptible worker, additionally, that relies on an injection point to make the wait time in CountOtherDBBackends() reduced from 5s to 0.3s for faster test runs. The tests rely on the contents of the server logs to check if a worker has been started or terminated: - LOG generated by worker_spi_main() at startup, once connection to database is done. - FATAL in bgworker_die() when terminated. A couple of tests run in the CI have showed that this method is stable enough. The safe_psql() calls that scan pg_stat_activity could be replaced with some poll_query_until() for more stability, if the current method proves to be an issue in the buildfarm. Author: Aya Iwata <iwata.aya@fujitsu.com> Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Reviewed-by: Ryo Matsumura <matsumura.ryo@fujitsu.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Reviewed-by: Peter Smith <smithpb2250@gmail.com> Discussion: https://postgr.es/m/OS7PR01MB11964335F36BE41021B62EAE8EAE4A@OS7PR01MB11964.jpnprd01.prod.outlook.compull/269/head
Michael Paquier
3 months ago
parent
c970bdc037
commit
f1e251be80
@ -0,0 +1,151 @@ |
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# Copyright (c) 2026, PostgreSQL Global Development Group |
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# Test background workers can be terminated by db commands |
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use strict; |
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use warnings FATAL => 'all'; |
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use PostgreSQL::Test::Cluster; |
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use PostgreSQL::Test::Utils; |
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use Test::More; |
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# This test depends on injection points to detect whether background workers |
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# remain. |
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if ($ENV{enable_injection_points} ne 'yes') |
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{ |
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plan skip_all => 'Injection points not supported by this build'; |
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} |
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# Ensure the worker_spi dynamic worker is launched on the specified database. |
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# Returns the PID of the worker launched. |
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sub launch_bgworker |
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{ |
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my ($node, $database, $testcase, $interruptible) = @_; |
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my $offset = -s $node->logfile; |
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# Launch a background worker on the given database. |
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my $pid = $node->safe_psql( |
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$database, qq( |
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SELECT worker_spi_launch($testcase, '$database'::regdatabase, 0, '{}', $interruptible); |
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)); |
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# Check that the bgworker is initialized. |
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$node->wait_for_log( |
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qr/LOG: worker_spi dynamic worker $testcase initialized with .*\..*/, |
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$offset); |
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my $result = $node->safe_psql($database, |
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"SELECT count(*) > 0 FROM pg_stat_activity WHERE pid = $pid;"); |
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is($result, 't', "dynamic bgworker $testcase launched"); |
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return $pid; |
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} |
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# Run query and verify that the bgworker with the specified PID has been |
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# terminated. |
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sub run_bgworker_interruptible_test |
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{ |
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my ($node, $command, $testname, $pid) = @_; |
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my $offset = -s $node->logfile; |
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$node->safe_psql('postgres', $command); |
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$node->wait_for_log( |
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qr/terminating background worker \"worker_spi dynamic\" due to administrator command/, |
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$offset); |
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my $result = $node->safe_psql('postgres', |
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"SELECT count(*) = 0 FROM pg_stat_activity WHERE pid = $pid;"); |
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is($result, 't', "dynamic bgworker stopped for $testname"); |
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} |
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my $node = PostgreSQL::Test::Cluster->new('mynode'); |
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$node->init; |
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$node->start; |
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# Check if the extension injection_points is available, as it may be |
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# possible that this script is run with installcheck, where the module |
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# would not be installed by default. |
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if (!$node->check_extension('injection_points')) |
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{ |
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plan skip_all => 'Extension injection_points not installed'; |
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} |
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$node->safe_psql('postgres', 'CREATE EXTENSION worker_spi;'); |
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# Launch a background worker without BGWORKER_INTERRUPTIBLE. |
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my $pid = launch_bgworker($node, 'postgres', 0, 'false'); |
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# Ensure CREATE DATABASE WITH TEMPLATE fails because a non-interruptible |
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# bgworker exists. |
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# The injection point 'procarray-reduce-count' reduces the number of backend |
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# retries, allowing for shorter test runs. See CountOtherDBBackends(). |
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$node->safe_psql('postgres', "CREATE EXTENSION injection_points;"); |
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$node->safe_psql('postgres', |
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"SELECT injection_points_attach('procarray-reduce-count', 'error');"); |
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my $stderr; |
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$node->psql( |
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'postgres', |
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"CREATE DATABASE testdb WITH TEMPLATE postgres", |
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stderr => \$stderr); |
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ok( $stderr =~ |
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"source database \"postgres\" is being accessed by other users", |
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"background worker blocked the database creation"); |
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# Confirm that the non-interruptible bgworker is still running. |
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my $result = $node->safe_psql( |
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"postgres", qq( |
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SELECT count(1) FROM pg_stat_activity |
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WHERE backend_type = 'worker_spi dynamic';)); |
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is($result, '1', |
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"background worker is still running after CREATE DATABASE WITH TEMPLATE"); |
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# Terminate the non-interruptible worker for the next tests. |
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$node->safe_psql( |
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"postgres", qq( |
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SELECT pg_terminate_backend(pid) |
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FROM pg_stat_activity WHERE backend_type = 'worker_spi dynamic';)); |
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# The injection point is not used anymore, release it. |
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$node->safe_psql('postgres', |
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"SELECT injection_points_detach('procarray-reduce-count');"); |
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# Check that BGWORKER_INTERRUPTIBLE allows background workers to be |
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# terminated with database-related commands. |
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# Test case 1: CREATE DATABASE WITH TEMPLATE |
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$pid = launch_bgworker($node, 'postgres', 1, 'true'); |
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run_bgworker_interruptible_test( |
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$node, |
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"CREATE DATABASE testdb WITH TEMPLATE postgres", |
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"CREATE DATABASE WITH TEMPLATE", $pid); |
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# Test case 2: ALTER DATABASE RENAME |
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$pid = launch_bgworker($node, 'testdb', 2, 'true'); |
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run_bgworker_interruptible_test( |
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$node, |
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"ALTER DATABASE testdb RENAME TO renameddb", |
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"ALTER DATABASE RENAME", $pid); |
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# Preparation for the next test, create a tablespace. |
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my $tablespace = PostgreSQL::Test::Utils::tempdir; |
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$node->safe_psql('postgres', |
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"CREATE TABLESPACE test_tablespace LOCATION '$tablespace'"); |
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# Test case 3: ALTER DATABASE SET TABLESPACE |
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$pid = launch_bgworker($node, 'renameddb', 3, 'true'); |
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run_bgworker_interruptible_test( |
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$node, |
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"ALTER DATABASE renameddb SET TABLESPACE test_tablespace", |
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"ALTER DATABASE SET TABLESPACE", $pid); |
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# Test case 4: DROP DATABASE |
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$pid = launch_bgworker($node, 'renameddb', 4, 'true'); |
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run_bgworker_interruptible_test( |
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$node, |
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"DROP DATABASE renameddb", |
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"DROP DATABASE", $pid); |
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done_testing(); |
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