私は Rails 4 のテンプレート キャッシング機能を広範囲に使用しています。多くのネストされたテンプレートとtouch: true多くのモデル。全体として、これは簡単に推論できる包括的なソリューションであることが証明されています。
私は最近、何百ものオブジェクトを反復処理し、それらに関連する他のオブジェクトを作成する複数のバックグラウンド ジョブが作成される機能を実装しました。これらの各オブジェクトが作成されると、同じユーザーが操作されます。
したがって、これら 2 つのジョブは並行して実行されます。
- ジョブ A: ユーザー 123 に触れるたびに、何百ものオブジェクトを連続して作成します
- ジョブ B: ユーザー 123 に触れるたびに、何百ものオブジェクトを連続して作成します
この機能をデプロイすると、postgres がデッドロックを検出し、互いに待機している 2 つのクエリをキャンセルすることがあることがわかりました。エラーに表示されるクエリは、常にタッチ クエリです (ユーザー 123 の updated_at を現在の時刻で更新します)。
pid: 33541 tid: 0 vtid: LOG: database system was shut down at 2014-03-27 19:57:11 EDT
pid: 33545 tid: 0 vtid: LOG: autovacuum launcher started
pid: 33539 tid: 0 vtid: LOG: database system is ready to accept connections
pid: 33626 tid: 0 vtid: 2/5 LOG: statement: set client_encoding to 'UTF8'
pid: 33626 tid: 0 vtid: 2/6 LOG: statement: set client_encoding to 'unicode'
pid: 33626 tid: 0 vtid: 2/7 LOG: statement: SET client_min_messages TO 'warning'
pid: 33626 tid: 0 vtid: 2/8 LOG: statement: SHOW client_min_messages
pid: 33626 tid: 0 vtid: 2/9 LOG: statement: SET client_min_messages TO 'panic'
pid: 33626 tid: 0 vtid: 2/10 LOG: statement: SET standard_conforming_strings = on
pid: 33626 tid: 0 vtid: 2/11 LOG: statement: SET client_min_messages TO 'warning'
pid: 33626 tid: 0 vtid: 2/12 LOG: statement: SET time zone 'UTC'
pid: 33626 tid: 0 vtid: 2/13 LOG: statement: SELECT oid, typname, typelem, typdelim, typinput FROM pg_type
pid: 33626 tid: 0 vtid: 2/14 LOG: statement: SHOW TIME ZONE
pid: 33626 tid: 0 vtid: 2/15 LOG: statement: SELECT 1
pid: 33626 tid: 0 vtid: 2/16 LOG: statement: SELECT COUNT(*)
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind in ('v','r')
AND c.relname = 'users'
AND n.nspname = ANY (current_schemas(false))
pid: 33626 tid: 0 vtid: 2/17 LOG: statement: SELECT attr.attname
FROM pg_attribute attr
INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
WHERE cons.contype = 'p'
AND cons.conrelid = '"users"'::regclass
pid: 33626 tid: 0 vtid: 2/18 LOG: statement: SELECT "users".* FROM "users" ORDER BY "users"."id" ASC LIMIT 1
pid: 33626 tid: 0 vtid: 2/19 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"users"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33627 tid: 0 vtid: 3/2 LOG: statement: set client_encoding to 'UTF8'
pid: 33627 tid: 0 vtid: 3/3 LOG: statement: set client_encoding to 'unicode'
pid: 33627 tid: 0 vtid: 3/4 LOG: statement: SET client_min_messages TO 'warning'
pid: 33627 tid: 0 vtid: 3/5 LOG: statement: SHOW client_min_messages
pid: 33627 tid: 0 vtid: 3/6 LOG: statement: SET client_min_messages TO 'panic'
pid: 33627 tid: 0 vtid: 3/7 LOG: statement: SET standard_conforming_strings = on
pid: 33627 tid: 0 vtid: 3/8 LOG: statement: SET client_min_messages TO 'warning'
pid: 33627 tid: 0 vtid: 3/9 LOG: statement: SET time zone 'UTC'
pid: 33627 tid: 0 vtid: 3/10 LOG: statement: SELECT oid, typname, typelem, typdelim, typinput FROM pg_type
pid: 33627 tid: 0 vtid: 3/11 LOG: statement: SHOW TIME ZONE
pid: 33627 tid: 0 vtid: 3/12 LOG: statement: SELECT 1
pid: 33627 tid: 0 vtid: 3/13 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"users"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33627 tid: 0 vtid: 3/14 LOG: statement: SELECT COUNT(*)
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind in ('v','r')
AND c.relname = 'users'
AND n.nspname = ANY (current_schemas(false))
pid: 33627 tid: 0 vtid: 3/15 LOG: statement: SELECT attr.attname
FROM pg_attribute attr
INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
WHERE cons.contype = 'p'
AND cons.conrelid = '"users"'::regclass
pid: 33627 tid: 0 vtid: 3/16 LOG: statement: SELECT id FROM "users" WHERE (bared_at IS NOT NULL) ORDER BY "users"."id" ASC LIMIT 1000
pid: 33628 tid: 0 vtid: 4/2 LOG: statement: set client_encoding to 'UTF8'
pid: 33628 tid: 0 vtid: 4/3 LOG: statement: set client_encoding to 'unicode'
pid: 33628 tid: 0 vtid: 4/4 LOG: statement: SET client_min_messages TO 'warning'
pid: 33628 tid: 0 vtid: 4/5 LOG: statement: SHOW client_min_messages
pid: 33628 tid: 0 vtid: 4/6 LOG: statement: SET client_min_messages TO 'panic'
pid: 33628 tid: 0 vtid: 4/7 LOG: statement: SET standard_conforming_strings = on
pid: 33628 tid: 0 vtid: 4/8 LOG: statement: SET client_min_messages TO 'warning'
pid: 33628 tid: 0 vtid: 4/9 LOG: statement: SET time zone 'UTC'
pid: 33628 tid: 0 vtid: 4/10 LOG: statement: SELECT oid, typname, typelem, typdelim, typinput FROM pg_type
pid: 33628 tid: 0 vtid: 4/11 LOG: statement: SHOW TIME ZONE
pid: 33628 tid: 0 vtid: 4/12 LOG: statement: SELECT 1
pid: 33628 tid: 0 vtid: 4/13 LOG: statement: SELECT id FROM "users" WHERE (bared_at IS NOT NULL) ORDER BY "users"."id" ASC LIMIT 1000
pid: 33627 tid: 0 vtid: 3/17 LOG: statement: SELECT COUNT(*)
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind in ('v','r')
AND c.relname = 'monkeys'
AND n.nspname = ANY (current_schemas(false))
pid: 33628 tid: 0 vtid: 4/14 LOG: statement: SELECT COUNT(*)
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind in ('v','r')
AND c.relname = 'monkeys'
AND n.nspname = ANY (current_schemas(false))
pid: 33627 tid: 0 vtid: 3/18 LOG: statement: SELECT attr.attname
FROM pg_attribute attr
INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
WHERE cons.contype = 'p'
AND cons.conrelid = '"monkeys"'::regclass
pid: 33628 tid: 0 vtid: 4/15 LOG: statement: SELECT attr.attname
FROM pg_attribute attr
INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
WHERE cons.contype = 'p'
AND cons.conrelid = '"monkeys"'::regclass
pid: 33627 tid: 0 vtid: 3/19 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"users_monkeys"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33628 tid: 0 vtid: 4/16 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"users_monkeys"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33627 tid: 0 vtid: 3/20 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"monkeys"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33628 tid: 0 vtid: 4/17 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"monkeys"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33627 tid: 0 vtid: 3/21 LOG: statement: SHOW search_path
pid: 33628 tid: 0 vtid: 4/18 LOG: statement: SHOW search_path
pid: 33627 tid: 0 vtid: 3/23 LOG: execute a1: SELECT COUNT(*) FROM "monkeys" INNER JOIN "users_monkeys" ON "monkeys"."id" = "users_monkeys"."monkey_id" WHERE "users_monkeys"."user_id" = $1 AND (((monkeys.name = 'recruiter') AND (monkeys.resource_type IS NULL) AND (monkeys.resource_id IS NULL)))
pid: 33627 tid: 0 vtid: 3/23 DETAIL: parameters: $1 = '2'
pid: 33628 tid: 0 vtid: 4/20 LOG: execute a1: SELECT COUNT(*) FROM "monkeys" INNER JOIN "users_monkeys" ON "monkeys"."id" = "users_monkeys"."monkey_id" WHERE "users_monkeys"."user_id" = $1 AND (((monkeys.name = 'recruiter') AND (monkeys.resource_type IS NULL) AND (monkeys.resource_id IS NULL)))
pid: 33628 tid: 0 vtid: 4/20 DETAIL: parameters: $1 = '2'
pid: 33627 tid: 0 vtid: 3/24 LOG: statement: SELECT "foos".* FROM "foos" WHERE "foos"."user_id" = 2 AND "foos"."fooer_id" = 1 LIMIT 1
pid: 33628 tid: 0 vtid: 4/21 LOG: statement: SELECT "foos".* FROM "foos" WHERE "foos"."user_id" = 1 AND "foos"."fooer_id" = 2 LIMIT 1
pid: 33628 tid: 0 vtid: 4/22 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"foos"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33627 tid: 0 vtid: 3/25 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"foos"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33628 tid: 0 vtid: 4/23 LOG: statement: SELECT COUNT(*)
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind in ('v','r')
AND c.relname = 'foos'
AND n.nspname = ANY (current_schemas(false))
pid: 33627 tid: 0 vtid: 3/26 LOG: statement: SELECT COUNT(*)
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind in ('v','r')
AND c.relname = 'foos'
AND n.nspname = ANY (current_schemas(false))
pid: 33628 tid: 0 vtid: 4/24 LOG: statement: SELECT attr.attname
FROM pg_attribute attr
INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
WHERE cons.contype = 'p'
AND cons.conrelid = '"foos"'::regclass
pid: 33627 tid: 0 vtid: 3/27 LOG: statement: SELECT attr.attname
FROM pg_attribute attr
INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1]
WHERE cons.contype = 'p'
AND cons.conrelid = '"foos"'::regclass
pid: 33628 tid: 0 vtid: 4/25 LOG: statement: BEGIN
pid: 33627 tid: 0 vtid: 3/28 LOG: statement: BEGIN
pid: 33628 tid: 0 vtid: 4/25 LOG: statement: SELECT 1 AS one FROM "foos" WHERE ("foos"."user_id" = 1 AND "foos"."id" != 4 AND "foos"."fooer_id" = 2) LIMIT 1
pid: 33627 tid: 0 vtid: 3/28 LOG: statement: SELECT 1 AS one FROM "foos" WHERE ("foos"."user_id" = 2 AND "foos"."id" != 3 AND "foos"."fooer_id" = 1) LIMIT 1
pid: 33628 tid: 0 vtid: 4/25 LOG: statement: SELECT a.attname, format_type(a.atttypid, a.atttypmod),
pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
FROM pg_attribute a LEFT JOIN pg_attrdef d
ON a.attrelid = d.adrelid AND a.attnum = d.adnum
WHERE a.attrelid = '"users"'::regclass
AND a.attnum > 0 AND NOT a.attisdropped
ORDER BY a.attnum
pid: 33627 tid: 0 vtid: 3/28 LOG: execute a2: SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1
pid: 33627 tid: 0 vtid: 3/28 DETAIL: parameters: $1 = '2'
pid: 33627 tid: 0 vtid: 3/28 LOG: statement: UPDATE "users" SET "updated_at" = '2014-03-27 23:58:02.619282' WHERE "users"."id" = 2
pid: 33628 tid: 0 vtid: 4/25 LOG: execute a2: SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1
pid: 33628 tid: 0 vtid: 4/25 DETAIL: parameters: $1 = '1'
pid: 33627 tid: 6723 vtid: 3/28 LOG: execute a2: SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1
pid: 33627 tid: 6723 vtid: 3/28 DETAIL: parameters: $1 = '1'
pid: 33628 tid: 0 vtid: 4/25 LOG: statement: UPDATE "users" SET "updated_at" = '2014-03-27 23:58:02.627175' WHERE "users"."id" = 1
pid: 33627 tid: 6723 vtid: 3/28 LOG: statement: UPDATE "users" SET "updated_at" = '2014-03-27 23:58:02.628983' WHERE "users"."id" = 1
pid: 33628 tid: 6724 vtid: 4/25 LOG: execute a2: SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1
pid: 33628 tid: 6724 vtid: 4/25 DETAIL: parameters: $1 = '2'
pid: 33628 tid: 6724 vtid: 4/25 LOG: statement: UPDATE "users" SET "updated_at" = '2014-03-27 23:58:02.632111' WHERE "users"."id" = 2
pid: 33627 tid: 6723 vtid: 3/28 ERROR: deadlock detected
pid: 33627 tid: 6723 vtid: 3/28 DETAIL: Process 33627 waits for ShareLock on transaction 6724; blocked by process 33628.
Process 33628 waits for ShareLock on transaction 6723; blocked by process 33627.
Process 33627: UPDATE "users" SET "updated_at" = '2014-03-27 23:58:02.628983' WHERE "users"."id" = 1
Process 33628: UPDATE "users" SET "updated_at" = '2014-03-27 23:58:02.632111' WHERE "users"."id" = 2
行もテーブルもロックされていないため、このデッドロックが発生することに驚いています。2 番目のトランザクションは、最初のトランザクションが終了するまで待つべきではありませんか?
更新: SQL のみの最小限のバグの再現: https://gist.github.com/jjb/9823023