diff --git a/doc/src/sgml/custom-rmgr.sgml b/doc/src/sgml/custom-rmgr.sgml
index 2893016cef..6d6909fc12 100644
--- a/doc/src/sgml/custom-rmgr.sgml
+++ b/doc/src/sgml/custom-rmgr.sgml
@@ -57,6 +57,13 @@ typedef struct RmgrData
} RmgrData;
+
+
+ The src/test/modules/test_custom_rmgrs module
+ contains a working example, which demonstrates usage of custom WAL
+ resource managers.
+
+
Then, register your new resource
manager.
diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile
index 7b3f292965..548469f7c1 100644
--- a/src/test/modules/Makefile
+++ b/src/test/modules/Makefile
@@ -16,6 +16,7 @@ SUBDIRS = \
spgist_name_ops \
test_bloomfilter \
test_copy_callbacks \
+ test_custom_rmgrs \
test_ddl_deparse \
test_extensions \
test_ginpostinglist \
diff --git a/src/test/modules/meson.build b/src/test/modules/meson.build
index c2e5f5ffd5..f2df05b1bc 100644
--- a/src/test/modules/meson.build
+++ b/src/test/modules/meson.build
@@ -10,6 +10,7 @@ subdir('spgist_name_ops')
subdir('ssl_passphrase_callback')
subdir('test_bloomfilter')
subdir('test_copy_callbacks')
+subdir('test_custom_rmgrs')
subdir('test_ddl_deparse')
subdir('test_extensions')
subdir('test_ginpostinglist')
diff --git a/src/test/modules/test_custom_rmgrs/.gitignore b/src/test/modules/test_custom_rmgrs/.gitignore
new file mode 100644
index 0000000000..5dcb3ff972
--- /dev/null
+++ b/src/test/modules/test_custom_rmgrs/.gitignore
@@ -0,0 +1,4 @@
+# Generated subdirectories
+/log/
+/results/
+/tmp_check/
diff --git a/src/test/modules/test_custom_rmgrs/Makefile b/src/test/modules/test_custom_rmgrs/Makefile
new file mode 100644
index 0000000000..b557e5888e
--- /dev/null
+++ b/src/test/modules/test_custom_rmgrs/Makefile
@@ -0,0 +1,24 @@
+# src/test/modules/test_custom_rmgrs/Makefile
+
+MODULE_big = test_custom_rmgrs
+OBJS = \
+ $(WIN32RES) \
+ test_custom_rmgrs.o
+PGFILEDESC = "test_custom_rmgrs - test custom WAL resource managers"
+
+EXTENSION = test_custom_rmgrs
+DATA = test_custom_rmgrs--1.0.sql
+
+EXTRA_INSTALL = contrib/pg_walinspect
+TAP_TESTS = 1
+
+ifdef USE_PGXS
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)
+else
+subdir = src/test/modules/test_custom_rmgrs
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+include $(top_srcdir)/contrib/contrib-global.mk
+endif
diff --git a/src/test/modules/test_custom_rmgrs/meson.build b/src/test/modules/test_custom_rmgrs/meson.build
new file mode 100644
index 0000000000..05ec06d6d5
--- /dev/null
+++ b/src/test/modules/test_custom_rmgrs/meson.build
@@ -0,0 +1,34 @@
+# FIXME: prevent install during main install, but not during test :/
+
+test_custom_rmgrs_sources = files(
+ 'test_custom_rmgrs.c',
+)
+
+if host_system == 'windows'
+ test_custom_rmgrs_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+ '--NAME', 'test_custom_rmgrs',
+ '--FILEDESC', 'test_custom_rmgrs - test custom WAL resource managers',])
+endif
+
+test_custom_rmgrs = shared_module('test_custom_rmgrs',
+ test_custom_rmgrs_sources,
+ kwargs: pg_mod_args,
+)
+testprep_targets += test_custom_rmgrs
+
+install_data(
+ 'test_custom_rmgrs.control',
+ 'test_custom_rmgrs--1.0.sql',
+ kwargs: contrib_data_args,
+)
+
+tests += {
+ 'name': 'test_custom_rmgrs',
+ 'sd': meson.current_source_dir(),
+ 'bd': meson.current_build_dir(),
+ 'tap': {
+ 'tests': [
+ 't/001_basic.pl',
+ ],
+ },
+}
diff --git a/src/test/modules/test_custom_rmgrs/t/001_basic.pl b/src/test/modules/test_custom_rmgrs/t/001_basic.pl
new file mode 100644
index 0000000000..a5e3a8834a
--- /dev/null
+++ b/src/test/modules/test_custom_rmgrs/t/001_basic.pl
@@ -0,0 +1,61 @@
+# Copyright (c) 2021-2022, PostgreSQL Global Development Group
+
+use strict;
+use warnings;
+
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+use Test::More;
+
+my $node = PostgreSQL::Test::Cluster->new('main');
+
+$node->init;
+$node->append_conf(
+ 'postgresql.conf', q{
+wal_level = 'replica'
+max_wal_senders = 4
+shared_preload_libraries = 'test_custom_rmgrs'
+});
+$node->start;
+
+# setup
+$node->safe_psql('postgres', 'CREATE EXTENSION test_custom_rmgrs');
+
+# pg_walinspect is required only for verifying test_custom_rmgrs output.
+# test_custom_rmgrs doesn't use/depend on it internally.
+$node->safe_psql('postgres', 'CREATE EXTENSION pg_walinspect');
+
+# make sure checkpoints don't interfere with the test.
+my $start_lsn = $node->safe_psql('postgres',
+ qq[SELECT lsn FROM pg_create_physical_replication_slot('regress_test_slot1', true, false);]);
+
+# write and save the WAL record's returned end LSN for verifying it later
+my $record_end_lsn = $node->safe_psql('postgres',
+ 'SELECT * FROM test_custom_rmgrs_insert_wal_record(\'payload123\')');
+
+# ensure the WAL is written and flushed to disk
+$node->safe_psql('postgres', 'SELECT pg_switch_wal()');
+
+my $end_lsn = $node->safe_psql('postgres', 'SELECT pg_current_wal_flush_lsn()');
+
+# check if our custom WAL resource manager has successfully registered with the server
+my $row_count =
+ $node->safe_psql('postgres',
+ qq[SELECT count(*) FROM pg_get_wal_resource_managers()
+ WHERE rm_name = 'test_custom_rmgrs';]);
+is($row_count, '1',
+ 'custom WAL resource manager has successfully registered with the server'
+);
+
+# check if our custom WAL resource manager has successfully written a WAL record
+my $expected = qq($record_end_lsn|test_custom_rmgrs|TEST_CUSTOM_RMGRS_MESSAGE|44|18|0|payload (10 bytes): payload123);
+my $result =
+ $node->safe_psql('postgres',
+ qq[SELECT end_lsn, resource_manager, record_type, record_length, main_data_length, fpi_length, description FROM pg_get_wal_records_info('$start_lsn', '$end_lsn')
+ WHERE resource_manager = 'test_custom_rmgrs';]);
+is($result, $expected,
+ 'custom WAL resource manager has successfully written a WAL record'
+);
+
+$node->stop;
+done_testing();
diff --git a/src/test/modules/test_custom_rmgrs/test_custom_rmgrs--1.0.sql b/src/test/modules/test_custom_rmgrs/test_custom_rmgrs--1.0.sql
new file mode 100644
index 0000000000..ea2c444939
--- /dev/null
+++ b/src/test/modules/test_custom_rmgrs/test_custom_rmgrs--1.0.sql
@@ -0,0 +1,16 @@
+/* src/test/modules/test_custom_rmgrs/test_custom_rmgrs--1.0.sql */
+
+-- complain if script is sourced in psql, rather than via CREATE EXTENSION
+\echo Use "CREATE EXTENSION test_custom_rmgrs" to load this file. \quit
+
+--
+-- test_custom_rmgrs_insert_wal_record()
+--
+-- Writes a simple message into WAL with the help of custom WAL
+-- resource manager.
+--
+CREATE FUNCTION test_custom_rmgrs_insert_wal_record(IN payload TEXT,
+ OUT lsn pg_lsn
+)
+AS 'MODULE_PATHNAME', 'test_custom_rmgrs_insert_wal_record'
+LANGUAGE C STRICT PARALLEL UNSAFE;
diff --git a/src/test/modules/test_custom_rmgrs/test_custom_rmgrs.c b/src/test/modules/test_custom_rmgrs/test_custom_rmgrs.c
new file mode 100644
index 0000000000..6e5270bf83
--- /dev/null
+++ b/src/test/modules/test_custom_rmgrs/test_custom_rmgrs.c
@@ -0,0 +1,139 @@
+/*--------------------------------------------------------------------------
+ *
+ * test_custom_rmgrs.c
+ * Code for testing custom WAL resource managers.
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * src/test/modules/test_custom_rmgrs/test_custom_rmgrs.c
+ *
+ * Custom WAL resource manager for records containing a simple textual
+ * payload, no-op redo, and no decoding.
+ *
+ * -------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/xlog.h"
+#include "access/xlog_internal.h"
+#include "access/xloginsert.h"
+#include "fmgr.h"
+#include "utils/pg_lsn.h"
+
+PG_MODULE_MAGIC;
+
+/*
+ * test_custom_rmgrs WAL record message.
+ */
+typedef struct xl_testcustomrmgrs_message
+{
+ Size message_size; /* size of the message */
+ char message[FLEXIBLE_ARRAY_MEMBER]; /* payload */
+} xl_testcustomrmgrs_message;
+
+#define SizeOfTestCustomRmgrsMessage (offsetof(xl_testcustomrmgrs_message, message))
+#define XLOG_TEST_CUSTOM_RMGRS_MESSAGE 0x00
+
+/*
+ * While developing or testing, use RM_EXPERIMENTAL_ID for rmid. For a real
+ * extension, reserve a new resource manager ID to avoid conflicting with
+ * other extensions; see:
+ * https://wiki.postgresql.org/wiki/CustomWALResourceManagers
+ */
+#define RM_TESTCUSTOMRMGRS_ID RM_EXPERIMENTAL_ID
+#define TESTCUSTOMRMGRS_NAME "test_custom_rmgrs"
+
+/* RMGR API, see xlog_internal.h */
+void testcustomrmgrs_redo(XLogReaderState *record);
+void testcustomrmgrs_desc(StringInfo buf, XLogReaderState *record);
+const char *testcustomrmgrs_identify(uint8 info);
+
+static RmgrData testcustomrmgrs_rmgr = {
+ .rm_name = TESTCUSTOMRMGRS_NAME,
+ .rm_redo = testcustomrmgrs_redo,
+ .rm_desc = testcustomrmgrs_desc,
+ .rm_identify = testcustomrmgrs_identify
+};
+
+/*
+ * Module load callback
+ */
+void
+_PG_init(void)
+{
+ /*
+ * In order to create our own custom resource manager, we have to be
+ * loaded via shared_preload_libraries. Otherwise, registration will fail.
+ */
+ RegisterCustomRmgr(RM_TESTCUSTOMRMGRS_ID, &testcustomrmgrs_rmgr);
+}
+
+/* RMGR API implementation */
+
+/*
+ * Redo is just a noop for this module, because we aren't testing recovery of
+ * any real structure.
+ */
+void
+testcustomrmgrs_redo(XLogReaderState *record)
+{
+ uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
+
+ if (info != XLOG_TEST_CUSTOM_RMGRS_MESSAGE)
+ elog(PANIC, "testcustomrmgrs_redo: unknown op code %u", info);
+}
+
+void
+testcustomrmgrs_desc(StringInfo buf, XLogReaderState *record)
+{
+ char *rec = XLogRecGetData(record);
+ uint8 info = XLogRecGetInfo(record) & ~XLR_INFO_MASK;
+
+ if (info == XLOG_TEST_CUSTOM_RMGRS_MESSAGE)
+ {
+ xl_testcustomrmgrs_message *xlrec = (xl_testcustomrmgrs_message *) rec;
+
+ appendStringInfo(buf, "payload (%zu bytes): ", xlrec->message_size);
+ appendBinaryStringInfo(buf, xlrec->message, xlrec->message_size);
+ }
+}
+
+const char *
+testcustomrmgrs_identify(uint8 info)
+{
+ if ((info & ~XLR_INFO_MASK) == XLOG_TEST_CUSTOM_RMGRS_MESSAGE)
+ return "TEST_CUSTOM_RMGRS_MESSAGE";
+
+ return NULL;
+}
+
+/*
+ * SQL function for writing a simple message into WAL with the help of custom
+ * WAL resource manager.
+ */
+PG_FUNCTION_INFO_V1(test_custom_rmgrs_insert_wal_record);
+Datum
+test_custom_rmgrs_insert_wal_record(PG_FUNCTION_ARGS)
+{
+ text *arg = PG_GETARG_TEXT_PP(0);
+ char *payload = VARDATA_ANY(arg);
+ Size len = VARSIZE_ANY_EXHDR(arg);
+ XLogRecPtr lsn;
+ xl_testcustomrmgrs_message xlrec;
+
+ xlrec.message_size = len;
+
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, SizeOfTestCustomRmgrsMessage);
+ XLogRegisterData((char *) payload, len);
+
+ /* Let's mark this record as unimportant, just in case. */
+ XLogSetRecordFlags(XLOG_MARK_UNIMPORTANT);
+
+ lsn = XLogInsert(RM_TESTCUSTOMRMGRS_ID, XLOG_TEST_CUSTOM_RMGRS_MESSAGE);
+
+ PG_RETURN_LSN(lsn);
+}
diff --git a/src/test/modules/test_custom_rmgrs/test_custom_rmgrs.control b/src/test/modules/test_custom_rmgrs/test_custom_rmgrs.control
new file mode 100644
index 0000000000..8113e0007d
--- /dev/null
+++ b/src/test/modules/test_custom_rmgrs/test_custom_rmgrs.control
@@ -0,0 +1,4 @@
+comment = 'Test code for custom WAL resource managers'
+default_version = '1.0'
+module_pathname = '$libdir/test_custom_rmgrs'
+relocatable = true