From 82472c69efe4c7d8d07023eb4ef3b08bb33b97f2 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 25 Aug 2026 19:12:09 +0300 Subject: [PATCH 3/3] Add tests for failing shmem allocations after startup To cover the failure cases that the previous commits hardened. Author: Ayush Tiwari Reviewed-by: Ashutosh Bapat Discussion: https://www.postgresql.org/message-id/CAJTYsWVRRWH48=PcuAo_2Y4Ap6M0QRmzxgUfFkNRtdWK74LjBQ@mail.gmail.com Backpatch-through: 19 --- src/test/modules/test_shmem/Makefile | 3 ++ src/test/modules/test_shmem/meson.build | 3 ++ .../test_shmem/t/001_late_shmem_alloc.pl | 47 ++++++++++++++++++- src/test/modules/test_shmem/test_shmem.c | 26 +++++++++- 4 files changed, 76 insertions(+), 3 deletions(-) diff --git a/src/test/modules/test_shmem/Makefile b/src/test/modules/test_shmem/Makefile index 2407f7462fe..fed8e29c8f5 100644 --- a/src/test/modules/test_shmem/Makefile +++ b/src/test/modules/test_shmem/Makefile @@ -2,6 +2,9 @@ PGFILEDESC = "test_shmem - test code for shmem allocations" +EXTRA_INSTALL = src/test/modules/injection_points +export enable_injection_points + MODULE_big = test_shmem OBJS = \ $(WIN32RES) \ diff --git a/src/test/modules/test_shmem/meson.build b/src/test/modules/test_shmem/meson.build index fb4bf328b8f..8f98f2c4e31 100644 --- a/src/test/modules/test_shmem/meson.build +++ b/src/test/modules/test_shmem/meson.build @@ -26,6 +26,9 @@ tests += { 'sd': meson.current_source_dir(), 'bd': meson.current_build_dir(), 'tap': { + 'env': { + 'enable_injection_points': get_option('injection_points') ? 'yes' : 'no', + }, 'tests': [ 't/001_late_shmem_alloc.pl', ], diff --git a/src/test/modules/test_shmem/t/001_late_shmem_alloc.pl b/src/test/modules/test_shmem/t/001_late_shmem_alloc.pl index 5cf07d071ec..b09889f4fb0 100644 --- a/src/test/modules/test_shmem/t/001_late_shmem_alloc.pl +++ b/src/test/modules/test_shmem/t/001_late_shmem_alloc.pl @@ -15,8 +15,50 @@ my $node = PostgreSQL::Test::Cluster->new('main'); $node->init; $node->start; +# Test a failure in initialization of the shared memory area. +SKIP: +{ + skip "injection points not supported by this build", + if $ENV{enable_injection_points} ne 'yes'; + $node->safe_psql("postgres", "CREATE EXTENSION injection_points;"); + $node->safe_psql("postgres", + "SELECT injection_points_attach('test-shmem-init', 'error');"); + + # A failure in the requesting shared memory should not affect server + # availability. The session should remain useful, however trying to create + # the same extension again will fail. + my (undef, undef, $stderr) = + $node->psql("postgres", "CREATE EXTENSION test_shmem;"); + like($stderr, + qr/error triggered for injection point test-shmem-init/, + "failure in initialization is reported"); + $node->safe_psql("postgres", + "SELECT injection_points_detach('test-shmem-init');"); + (undef, undef, $stderr) = + $node->psql("postgres", "CREATE EXTENSION test_shmem;"); + like($stderr, qr/cannot attach to shared memory/, + "post-init extension creation fails"); + + # Only a server restart can remove the partially allocated shared memory + # area. + $node->restart; +} + +# Test failure when the request is larger than the memory reserved for +# after-startup requests. +my $session = $node->background_psql('postgres', on_error_stop => 0); +$session->query(q[SET test_shmem.area_size = '128kB';], verbose => 0); +$session->query("CREATE EXTENSION test_shmem;", verbose => 0); +like($session->{stderr}, qr/not enough shared memory/, + "an after-startup request larger than the reserve fails"); -$node->safe_psql("postgres", "CREATE EXTENSION test_shmem;"); +# The server and the backend should still be available. Since there was only one +# area requested, the failure did not change anything in the shared memory. +# Verify that the request for smaller area succeeds in the same session. +$session->{stderr} = ''; +$session->query("SET test_shmem.area_size = default;", verbose => 0); +$session->query_safe("CREATE EXTENSION test_shmem;", verbose => 0); +$session->quit; # Check that the attach counter is incremented on a new connection my $attach_count1 = @@ -28,8 +70,9 @@ cmp_ok($attach_count2, '>', $attach_count1, $node->stop; ### -# Test that loading via shared_preload_libraries also works +# Test that loading via shared_preload_libraries also works, even for large request. ### +$node->append_conf('postgresql.conf', "test_shmem.area_size = '128kB'"); $node->append_conf('postgresql.conf', "shared_preload_libraries = 'test_shmem'"); $node->start; diff --git a/src/test/modules/test_shmem/test_shmem.c b/src/test/modules/test_shmem/test_shmem.c index 9bd4012b435..2956f488135 100644 --- a/src/test/modules/test_shmem/test_shmem.c +++ b/src/test/modules/test_shmem/test_shmem.c @@ -17,9 +17,13 @@ #include "postgres.h" +#include + #include "fmgr.h" #include "miscadmin.h" #include "storage/shmem.h" +#include "utils/guc.h" +#include "utils/injection_point.h" PG_MODULE_MAGIC; @@ -29,11 +33,14 @@ typedef struct TestShmemData int value; bool initialized; int attach_count; + char variable_sized_array[FLEXIBLE_ARRAY_MEMBER]; } TestShmemData; static TestShmemData *TestShmem; static bool attached_or_initialized = false; +static int test_shmem_area_size = sizeof(TestShmemData); +static bool test_shmem_guc_defined = false; static void test_shmem_request(void *arg); static void test_shmem_init(void *arg); @@ -52,7 +59,7 @@ test_shmem_request(void *arg) elog(LOG, "test_shmem_request callback called"); ShmemRequestStruct(.name = "test_shmem area", - .size = sizeof(TestShmemData), + .size = test_shmem_area_size, .ptr = (void **) &TestShmem); } @@ -60,6 +67,8 @@ static void test_shmem_init(void *arg) { elog(LOG, "init callback called"); + /* Induce an error while initializing shared structure. */ + INJECTION_POINT("test-shmem-init", NULL); if (TestShmem->initialized) elog(ERROR, "shmem area already initialized"); TestShmem->initialized = true; @@ -86,6 +95,21 @@ void _PG_init(void) { elog(LOG, "test_shmem module's _PG_init called"); + + if (!test_shmem_guc_defined) + { + DefineCustomIntVariable("test_shmem.area_size", + "Size of the shmem area to request.", + NULL, + &test_shmem_area_size, + sizeof(TestShmemData), + sizeof(TestShmemData), INT_MAX, + PGC_USERSET, + GUC_UNIT_BYTE, + NULL, NULL, NULL); + MarkGUCPrefixReserved("test_shmem"); + test_shmem_guc_defined = true; + } RegisterShmemCallbacks(&TestShmemCallbacks); } -- 2.47.3