]> git.ipfire.org Git - thirdparty/postgresql.git/commitdiff
Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.
authorNoah Misch <noah@leadboat.com>
Sun, 24 Oct 2021 01:36:38 +0000 (18:36 -0700)
committerNoah Misch <noah@leadboat.com>
Sun, 24 Oct 2021 01:36:43 +0000 (18:36 -0700)
CIC and REINDEX CONCURRENTLY assume backends see their catalog changes
no later than each backend's next transaction start.  That failed to
hold when a backend absorbed a relevant invalidation in the middle of
running RelationBuildDesc() on the CIC index.  Queries that use the
resulting index can silently fail to find rows.  Fix this for future
index builds by making RelationBuildDesc() loop until it finishes
without accepting a relevant invalidation.  It may be necessary to
reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.
Back-patch to 9.6 (all supported versions).

Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres
Freund.

Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com

src/backend/utils/cache/inval.c
src/backend/utils/cache/relcache.c
src/bin/pgbench/t/022_cic.pl [new file with mode: 0644]
src/include/utils/inval.h
src/include/utils/relcache.h
src/test/perl/PostgresNode.pm
src/tools/pgindent/typedefs.list

index c7dc8267cf7210448ab39c3ace81c55f7651825e..1fdc904087cd8cadcbfd7c93f653e4b8e136dc92 100644 (file)
@@ -584,7 +584,7 @@ LocalExecuteInvalidationMessage(SharedInvalidationMessage *msg)
                        int                     i;
 
                        if (msg->rc.relId == InvalidOid)
-                               RelationCacheInvalidate();
+                               RelationCacheInvalidate(false);
                        else
                                RelationCacheInvalidateEntry(msg->rc.relId);
 
@@ -641,12 +641,18 @@ LocalExecuteInvalidationMessage(SharedInvalidationMessage *msg)
  */
 void
 InvalidateSystemCaches(void)
+{
+       InvalidateSystemCachesExtended(false);
+}
+
+void
+InvalidateSystemCachesExtended(bool debug_discard)
 {
        int                     i;
 
        InvalidateCatalogSnapshot();
        ResetCatalogCaches();
-       RelationCacheInvalidate();      /* gets smgr and relmap too */
+       RelationCacheInvalidate(debug_discard); /* gets smgr and relmap too */
 
        for (i = 0; i < syscache_callback_count; i++)
        {
@@ -717,7 +723,7 @@ AcceptInvalidationMessages(void)
                if (recursion_depth < 3)
                {
                        recursion_depth++;
-                       InvalidateSystemCaches();
+                       InvalidateSystemCachesExtended(true);
                        recursion_depth--;
                }
        }
index 73f01163a3f73ad44a5a1918d5cb91a14d571e54..b790777108356f82532d705d709cf2571b079051 100644 (file)
@@ -144,6 +144,24 @@ bool               criticalSharedRelcachesBuilt = false;
  */
 static long relcacheInvalsReceived = 0L;
 
+/*
+ * in_progress_list is a stack of ongoing RelationBuildDesc() calls.  CREATE
+ * INDEX CONCURRENTLY makes catalog changes under ShareUpdateExclusiveLock.
+ * It critically relies on each backend absorbing those changes no later than
+ * next transaction start.  Hence, RelationBuildDesc() loops until it finishes
+ * without accepting a relevant invalidation.  (Most invalidation consumers
+ * don't do this.)
+ */
+typedef struct inprogressent
+{
+       Oid                     reloid;                 /* OID of relation being built */
+       bool            invalidated;    /* whether an invalidation arrived for it */
+} InProgressEnt;
+
+static InProgressEnt *in_progress_list;
+static int     in_progress_list_len;
+static int     in_progress_list_maxlen;
+
 /*
  * eoxact_list[] stores the OIDs of relations that (might) need AtEOXact
  * cleanup work.  This list intentionally has limited size; if it overflows,
@@ -1088,11 +1106,27 @@ equalPartitionDescs(PartitionKey key, PartitionDesc partdesc1,
 static Relation
 RelationBuildDesc(Oid targetRelId, bool insertIt)
 {
+       int                     in_progress_offset;
        Relation        relation;
        Oid                     relid;
        HeapTuple       pg_class_tuple;
        Form_pg_class relp;
 
+       /* Register to catch invalidation messages */
+       if (in_progress_list_len >= in_progress_list_maxlen)
+       {
+               int                     allocsize;
+
+               allocsize = in_progress_list_maxlen * 2;
+               in_progress_list = repalloc(in_progress_list,
+                                                                       allocsize * sizeof(*in_progress_list));
+               in_progress_list_maxlen = allocsize;
+       }
+       in_progress_offset = in_progress_list_len++;
+       in_progress_list[in_progress_offset].reloid = targetRelId;
+retry:
+       in_progress_list[in_progress_offset].invalidated = false;
+
        /*
         * find the tuple in pg_class corresponding to the given relation id
         */
@@ -1102,7 +1136,11 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
         * if no such tuple exists, return NULL
         */
        if (!HeapTupleIsValid(pg_class_tuple))
+       {
+               Assert(in_progress_offset + 1 == in_progress_list_len);
+               in_progress_list_len--;
                return NULL;
+       }
 
        /*
         * get information from the pg_class_tuple
@@ -1246,6 +1284,21 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
         */
        heap_freetuple(pg_class_tuple);
 
+       /*
+        * If an invalidation arrived mid-build, start over.  Between here and the
+        * end of this function, don't add code that does or reasonably could read
+        * system catalogs.  That range must be free from invalidation processing
+        * for the !insertIt case.  For the insertIt case, RelationCacheInsert()
+        * will enroll this relation in ordinary relcache invalidation processing,
+        */
+       if (in_progress_list[in_progress_offset].invalidated)
+       {
+               RelationDestroyRelation(relation, false);
+               goto retry;
+       }
+       Assert(in_progress_offset + 1 == in_progress_list_len);
+       in_progress_list_len--;
+
        /*
         * Insert newly created relation into relcache hash table, if requested.
         *
@@ -2469,6 +2522,14 @@ RelationClearRelation(Relation relation, bool rebuild)
 
                /* Build temporary entry, but don't link it into hashtable */
                newrel = RelationBuildDesc(save_relid, false);
+
+               /*
+                * Between here and the end of the swap, don't add code that does or
+                * reasonably could read system catalogs.  That range must be free
+                * from invalidation processing.  See RelationBuildDesc() manipulation
+                * of in_progress_list.
+                */
+
                if (newrel == NULL)
                {
                        /*
@@ -2660,6 +2721,14 @@ RelationCacheInvalidateEntry(Oid relationId)
                relcacheInvalsReceived++;
                RelationFlushRelation(relation);
        }
+       else
+       {
+               int                     i;
+
+               for (i = 0; i < in_progress_list_len; i++)
+                       if (in_progress_list[i].reloid == relationId)
+                               in_progress_list[i].invalidated = true;
+       }
 }
 
 /*
@@ -2691,9 +2760,14 @@ RelationCacheInvalidateEntry(Oid relationId)
  *      second pass processes nailed-in-cache items before other nondeletable
  *      items.  This should ensure that system catalogs are up to date before
  *      we attempt to use them to reload information about other open relations.
+ *
+ *      After those two phases of work having immediate effects, we normally
+ *      signal any RelationBuildDesc() on the stack to start over.  However, we
+ *      don't do this if called as part of debug_discard_caches.  Otherwise,
+ *      RelationBuildDesc() would become an infinite loop.
  */
 void
-RelationCacheInvalidate(void)
+RelationCacheInvalidate(bool debug_discard)
 {
        HASH_SEQ_STATUS status;
        RelIdCacheEnt *idhentry;
@@ -2701,6 +2775,7 @@ RelationCacheInvalidate(void)
        List       *rebuildFirstList = NIL;
        List       *rebuildList = NIL;
        ListCell   *l;
+       int                     i;
 
        /*
         * Reload relation mapping data before starting to reconstruct cache.
@@ -2787,6 +2862,11 @@ RelationCacheInvalidate(void)
                RelationClearRelation(relation, true);
        }
        list_free(rebuildList);
+
+       if (!debug_discard)
+               /* Any RelationBuildDesc() on the stack must start over. */
+               for (i = 0; i < in_progress_list_len; i++)
+                       in_progress_list[i].invalidated = true;
 }
 
 /*
@@ -2859,6 +2939,13 @@ AtEOXact_RelationCache(bool isCommit)
        RelIdCacheEnt *idhentry;
        int                     i;
 
+       /*
+        * Forget in_progress_list.  This is relevant when we're aborting due to
+        * an error during RelationBuildDesc().
+        */
+       Assert(in_progress_list_len == 0 || !isCommit);
+       in_progress_list_len = 0;
+
        /*
         * Unless the eoxact_list[] overflowed, we only need to examine the rels
         * listed in it.  Otherwise fall back on a hash_seq_search scan.
@@ -3008,6 +3095,14 @@ AtEOSubXact_RelationCache(bool isCommit, SubTransactionId mySubid,
        RelIdCacheEnt *idhentry;
        int                     i;
 
+       /*
+        * Forget in_progress_list.  This is relevant when we're aborting due to
+        * an error during RelationBuildDesc().  We don't commit subtransactions
+        * during RelationBuildDesc().
+        */
+       Assert(in_progress_list_len == 0 || !isCommit);
+       in_progress_list_len = 0;
+
        /*
         * Unless the eoxact_list[] overflowed, we only need to examine the rels
         * listed in it.  Otherwise fall back on a hash_seq_search scan.  Same
@@ -3497,6 +3592,7 @@ void
 RelationCacheInitialize(void)
 {
        HASHCTL         ctl;
+       int                     allocsize;
 
        /*
         * make sure cache memory context exists
@@ -3513,6 +3609,15 @@ RelationCacheInitialize(void)
        RelationIdCache = hash_create("Relcache by OID", INITRELCACHESIZE,
                                                                  &ctl, HASH_ELEM | HASH_BLOBS);
 
+       /*
+        * reserve enough in_progress_list slots for many cases
+        */
+       allocsize = 4;
+       in_progress_list =
+               MemoryContextAlloc(CacheMemoryContext,
+                                                  allocsize * sizeof(*in_progress_list));
+       in_progress_list_maxlen = allocsize;
+
        /*
         * relation mapper needs to be initialized too
         */
diff --git a/src/bin/pgbench/t/022_cic.pl b/src/bin/pgbench/t/022_cic.pl
new file mode 100644 (file)
index 0000000..a1cda5b
--- /dev/null
@@ -0,0 +1,93 @@
+
+# Copyright (c) 2021, PostgreSQL Global Development Group
+
+# Test CREATE INDEX CONCURRENTLY with concurrent modifications
+use strict;
+use warnings;
+
+use Config;
+use PostgresNode;
+use TestLib;
+
+use Test::More tests => 4;
+
+my ($node, $result);
+
+#
+# Test set-up
+#
+$node = get_new_node('CIC_test');
+$node->init;
+$node->append_conf('postgresql.conf', 'lock_timeout = 180000');
+$node->start;
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i)));
+$node->safe_psql(
+       'postgres', q(
+       CREATE FUNCTION heapallindexed() RETURNS void AS $$
+       DECLARE
+               count_seqscan int;
+               count_idxscan int;
+       BEGIN
+               count_seqscan := (SELECT count(*) FROM tbl);
+               SET enable_seqscan = off;
+               count_idxscan := (SELECT count(*) FROM tbl);
+               RESET enable_seqscan;
+               IF count_seqscan <> count_idxscan THEN
+                       RAISE 'seqscan found % rows, but idxscan found % rows',
+                               count_seqscan, count_idxscan;
+               END IF;
+       END
+       $$ LANGUAGE plpgsql;
+));
+
+#
+# Stress CIC with pgbench
+#
+
+# Run background pgbench with CIC. We cannot mix-in this script into single
+# pgbench: CIC will deadlock with itself occasionally.
+my $pgbench_out   = '';
+my $pgbench_timer = IPC::Run::timeout(180);
+my $pgbench_h     = $node->background_pgbench(
+       '--no-vacuum --client=1 --transactions=200',
+       {
+               '002_pgbench_concurrent_cic' => q(
+                       DROP INDEX CONCURRENTLY idx;
+                       CREATE INDEX CONCURRENTLY idx ON tbl(i);
+                       BEGIN ISOLATION LEVEL REPEATABLE READ;
+                       SELECT heapallindexed();
+                       ROLLBACK;
+                  )
+       },
+       \$pgbench_out,
+       $pgbench_timer);
+
+# Run pgbench.
+$node->pgbench(
+       '--no-vacuum --client=5 --transactions=200',
+       0,
+       [qr{actually processed}],
+       [qr{^$}],
+       'concurrent INSERTs',
+       {
+               '002_pgbench_concurrent_transaction' => q(
+                       BEGIN;
+                       INSERT INTO tbl VALUES(0);
+                       COMMIT;
+                 ),
+               '002_pgbench_concurrent_transaction_savepoints' => q(
+                       BEGIN;
+                       SAVEPOINT s1;
+                       INSERT INTO tbl VALUES(0);
+                       COMMIT;
+                 )
+       });
+
+$pgbench_h->pump_nb;
+$pgbench_h->finish();
+unlike($pgbench_out, qr/aborted in command/, "pgbench with CIC works");
+
+# done
+$node->stop;
+done_testing();
index 7a66d466f703bb1832183acda25aef4a69cd0373..31a54e5aa3cbeb00ef53e318867a90bfd725228b 100644 (file)
@@ -63,4 +63,5 @@ extern void CacheRegisterRelcacheCallback(RelcacheCallbackFunction func,
 extern void CallSyscacheCallbacks(int cacheid, uint32 hashvalue);
 
 extern void InvalidateSystemCaches(void);
+extern void InvalidateSystemCachesExtended(bool debug_discard);
 #endif                                                 /* INVAL_H */
index 54394303a8578de89dd4f768ccc9522505c0cf4c..8c4e2642b84f97e59e530619123beddfe4d96207 100644 (file)
@@ -120,7 +120,7 @@ extern void RelationForgetRelation(Oid rid);
 
 extern void RelationCacheInvalidateEntry(Oid relationId);
 
-extern void RelationCacheInvalidate(void);
+extern void RelationCacheInvalidate(bool debug_discard);
 
 extern void RelationCloseSmgrByOid(Oid relationId);
 
index c663e91a7b08944b46b7433599a9eecc0ec8f451..e0fa7917603d975039a9e85be5594bcc6cc58c43 100644 (file)
@@ -1481,6 +1481,141 @@ sub psql
        }
 }
 
+# Common sub of pgbench-invoking interfaces.  Makes any requested script files
+# and returns pgbench command-line options causing use of those files.
+sub _pgbench_make_files
+{
+       my ($self, $files) = @_;
+       my @file_opts;
+
+       if (defined $files)
+       {
+
+               # note: files are ordered for determinism
+               for my $fn (sort keys %$files)
+               {
+                       my $filename = $self->basedir . '/' . $fn;
+                       push @file_opts, '-f', $filename;
+
+                       # cleanup file weight
+                       $filename =~ s/\@\d+$//;
+
+                       #push @filenames, $filename;
+                       # filenames are expected to be unique on a test
+                       if (-e $filename)
+                       {
+                               ok(0, "$filename must not already exist");
+                               unlink $filename or die "cannot unlink $filename: $!";
+                       }
+                       TestLib::append_to_file($filename, $$files{$fn});
+               }
+       }
+
+       return @file_opts;
+}
+
+=pod
+
+=item $node->pgbench($opts, $stat, $out, $err, $name, $files, @args)
+
+Invoke B<pgbench>, with parameters and files.
+
+=over
+
+=item $opts
+
+Options as a string to be split on spaces.
+
+=item $stat
+
+Expected exit status.
+
+=item $out
+
+Reference to a regexp list that must match stdout.
+
+=item $err
+
+Reference to a regexp list that must match stderr.
+
+=item $name
+
+Name of test for error messages.
+
+=item $files
+
+Reference to filename/contents dictionary.
+
+=item @args
+
+Further raw options or arguments.
+
+=back
+
+=cut
+
+sub pgbench
+{
+       local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+       my ($self, $opts, $stat, $out, $err, $name, $files, @args) = @_;
+       my @cmd = (
+               'pgbench',
+               split(/\s+/, $opts),
+               $self->_pgbench_make_files($files), @args);
+
+       $self->command_checks_all(\@cmd, $stat, $out, $err, $name);
+}
+
+=pod
+
+=item $node->background_pgbench($opts, $files, \$stdout, $timer) => harness
+
+Invoke B<pgbench> and return an IPC::Run harness object.  The process's stdin
+is empty, and its stdout and stderr go to the $stdout scalar reference.  This
+allows the caller to act on other parts of the system while B<pgbench> is
+running.  Errors from B<pgbench> are the caller's problem.
+
+The specified timer object is attached to the harness, as well.  It's caller's
+responsibility to select the timeout length, and to restart the timer after
+each command if the timeout is per-command.
+
+Be sure to "finish" the harness when done with it.
+
+=over
+
+=item $opts
+
+Options as a string to be split on spaces.
+
+=item $files
+
+Reference to filename/contents dictionary.
+
+=back
+
+=cut
+
+sub background_pgbench
+{
+       my ($self, $opts, $files, $stdout, $timer) = @_;
+
+       my @cmd =
+         ('pgbench', split(/\s+/, $opts), $self->_pgbench_make_files($files));
+
+       local $ENV{PGHOST} = $self->host;
+       local $ENV{PGPORT} = $self->port;
+
+       my $stdin = "";
+       # IPC::Run would otherwise append to existing contents:
+       $$stdout = "" if ref($stdout);
+
+       my $harness = IPC::Run::start \@cmd, '<', \$stdin, '>', $stdout, '2>&1',
+         $timer;
+
+       return $harness;
+}
+
 =pod
 
 =item $node->poll_query_until($dbname, $query [, $expected ])
index 934e8b36f78224783473fcafce9a82f44572b606..c463596ea7ba331509e7eca80458aa6d379b354f 100644 (file)
@@ -1002,6 +1002,7 @@ ImportForeignSchemaStmt
 ImportForeignSchemaType
 ImportForeignSchema_function
 ImportQual
+InProgressEnt
 IncludeWal
 InclusionOpaque
 IncrementVarSublevelsUp_context