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Postgres：奇怪的行为乐观锁定

2017-04-06 118 views
1

我正在调试使用JPA/Hibernate和Postgres（9.6.2）的Java应用程序的奇怪行为。Postgres：奇怪的行为乐观锁定

应用程序有3个实体：用户，国家，用户事件。

Hibernate将其映射到4个表格：用户，国家，userevent，hibernate_sequences。

用户实体具有版本列（@版本）和乐观锁定的主题。 @GeneratedValue（策略= GenerationType.TABLE），其主键为“id”。用户表将获得最多的读写次数（最受欢迎的表格）。

我创建了一个情侣的压力测试来模拟高负载，发现以下错误，当我运行它们在Postgres的记录（请注意，导致它的更新查询）：

ERROR: deadlock detected 
DETAIL: Process 46758 waits for ShareLock on transaction 1580660; blocked by process 46759. 
    Process 46759 waits for AccessExclusiveLock on tuple (97,26) of relation 17353 of database 16385; blocked by process 46758. 

    Process 46758: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 
    Process 46759: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 

    HINT: See server log for query details. 
    CONTEXT: while updating tuple (97,26) in relation "users"

我了解Postgres已经共享和独家;行，表或索引级锁。以错误顺序获取相同对象可能会导致死锁。

但是对于这个特定的情况，为什么我会乐观锁定得到死锁？我期望一个事务成功，一个在这种情况下返回0个UPDATE。

表，FK，它们的指标描述如下：

################################################################################################## 

             Table "public.users" 
     Column  |   Type    | Modifiers | Storage | Stats target | Description 
-------------------+-----------------------------+-----------+----------+--------------+------------- 
id    | bigint      | not null | plain |    | 
confirmationstate | character varying(20)  | not null | extended |    | 
created   | timestamp without time zone | not null | plain |    | 
dateofbirth  | date      | not null | plain |    | 
email    | character varying(255)  | not null | extended |    | 
firstname   | character varying(100)  | not null | extended |    | 
gender   | character varying(10)  | not null | extended |    | 
lastname   | character varying(100)  | not null | extended |    | 
lastusedlocale | character varying(5)  |   | extended |    | 
middlename  | character varying(100)  |   | extended |    | 
passwordhash  | bytea      | not null | extended |    | 
passwordsalt  | bytea      | not null | extended |    | 
phone    | character varying(50)  |   | extended |    | 
role    | character varying(50)  | not null | extended |    | 
signinstate  | character varying(20)  | not null | extended |    | 
updated   | timestamp without time zone | not null | plain |    | 
username   | character varying(255)  |   | extended |    | 
version   | bigint      |   | plain |    | 
country_iso  | character varying(2)  |   | extended |    | 
Indexes: 
    "users_pkey" PRIMARY KEY, btree (id) 
    "email_idx" UNIQUE CONSTRAINT, btree (email) 
    "username_idx" UNIQUE CONSTRAINT, btree (username) 
    "firstname_idx" btree (firstname) 
    "lastname_idx" btree (lastname) 
    "phone_idx" btree (phone) 
Foreign-key constraints: 
    "fk_ghgfskd1hgobolp0fh20i6h14" FOREIGN KEY (country_iso) REFERENCES countries(iso) 
Referenced by: 
    TABLE "userevents" CONSTRAINT "fk_69tm2wh9hkakap0uyjw41c61h" FOREIGN KEY (targetuser_id) REFERENCES users(id) 
    TABLE "userevents" CONSTRAINT "fk_nov1tso5k93h4m88unjy4f2kl" FOREIGN KEY (user_id) REFERENCES users(id) 

################################################################################################## 

           Table "public.countries" 
    Column |   Type   | Modifiers | Storage | Stats target | Description 
------------+------------------------+-----------+----------+--------------+------------- 
iso  | character varying(2) | not null | extended |    | 
iso3  | character varying(3) |   | extended |    | 
name  | character varying(80) |   | extended |    | 
nativename | character varying(150) |   | extended |    | 
numcode | integer    |   | plain |    | 
phonecode | integer    | not null | plain |    | 
Indexes: 
    "countries_pkey" PRIMARY KEY, btree (iso) 
    "iso3_idx" UNIQUE CONSTRAINT, btree (iso3) 
    "nativename_idx" btree (nativename) 
Referenced by: 
    TABLE "users" CONSTRAINT "fk_ghgfskd1hgobolp0fh20i6h14" FOREIGN KEY (country_iso) REFERENCES countries(iso)  

################################################################################################## 

            Table "public.userevents" 
    Column  |   Type    | Modifiers | Storage | Stats target | Description 
---------------+-----------------------------+-----------+----------+--------------+------------- 
id   | bigint      | not null | plain |    | 
data   | bytea      |   | extended |    | 
ip   | character varying(255)  | not null | extended |    | 
time   | timestamp without time zone | not null | plain |    | 
type   | character varying(15)  | not null | extended |    | 
url   | character varying(2000)  |   | extended |    | 
targetuser_id | bigint      |   | plain |    | 
user_id  | bigint      | not null | plain |    | 
Indexes: 
    "userevents_pkey" PRIMARY KEY, btree (id) 
    "usertypetime_idx" btree (user_id, type, "time") 
Foreign-key constraints: 
    "fk_69tm2wh9hkakap0uyjw41c61h" FOREIGN KEY (targetuser_id) REFERENCES users(id) 
    "fk_nov1tso5k93h4m88unjy4f2kl" FOREIGN KEY (user_id) REFERENCES users(id) 

##################################################################################################  

Table "public.hibernate_sequences" 
     Column   |   Type   | Modifiers | Storage | Stats target | Description 
------------------------+------------------------+-----------+----------+--------------+------------- 
sequence_name   | character varying(255) |   | extended |    | 
sequence_next_hi_value | integer    |   | plain |    | 

##################################################################################################

编辑1：

先生pozs建议看一下现有的圆形FKS问题，并提供更多的细节在交易中发生了什么。在这个模式中我没有循环FK，所以我在Postgres中设置了日志记录并试图找出问题。

以下是导致死锁的2个进程的所有语句的完整日志。

过程1日志：

2017-04-11 12:41:31 PDT  73842 LOG: 00000: execute S_2: BEGIN  
2017-04-11 12:41:31 PDT  73842 LOG: 00000: execute S_3: select user0_.id as id1_2_0_, user0_.confirmationState as confirma2_2_0_, user0_.country_iso as country19_2_0_, user0_.created as created3_2_0_, user0_.dateOfBirth as dateOfBi4_2_0_, user0_.email as email5_2_0_, user0_.firstName as firstNam6_2_0_, user0_.gender as gender7_2_0_, user0_.lastName as lastName8_2_0_, user0_.lastUsedLocale as lastUsed9_2_0_, user0_.middleName as middleN10_2_0_, user0_.passwordHash as passwor11_2_0_, user0_.passwordSalt as passwor12_2_0_, user0_.phone as phone13_2_0_, user0_.role as role14_2_0_, user0_.signInState as signInS15_2_0_, user0_.updated as updated16_2_0_, user0_.username as usernam17_2_0_, user0_.version as version18_2_0_, country1_.iso as iso1_0_1_, country1_.iso3 as iso2_0_1_, country1_.name as name3_0_1_, country1_.nativeName as nativeNa4_0_1_, country1_.numCode as numCode5_0_1_, country1_.phoneCode as phoneCod6_0_1_ from users user0_ left outer join countries country1_ on user0_.country_iso=country1_.iso where user0_.id=$1 
2017-04-11 12:41:31 PDT  73842 DETAIL: parameters: $1 = '10' 
2017-04-11 12:41:31 PDT  73842 LOG: 00000: execute S_10: select country0_.iso as iso1_0_, country0_.iso3 as iso2_0_, country0_.name as name3_0_, country0_.nativeName as nativeNa4_0_, country0_.numCode as numCode5_0_, country0_.phoneCode as phoneCod6_0_ from countries country0_ order by country0_.nativeName, country0_.name 
2017-04-11 12:41:31 PDT  73842 LOG: 00000: execute S_4: insert into userEvents (data, ip, targetUser_id, time, type, url, user_id, id) values ($1, $2, $3, $4, $5, $6, $7, $8) 
2017-04-11 12:41:31 PDT  73842 DETAIL: parameters: $1 = '\x04545...LONG_BINARY_DATA...d', $2 = '192.168.1.2', $3 = '10', $4 = '2017-04-11 19:41:31.268', $5 = 'UPDATE', $6 = 'http://example.org', $7 = '10', $8 = '201243' 
2017-04-11 12:41:31 PDT  73842 LOG: 00000: execute S_7: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 
2017-04-11 12:41:31 PDT  73842 DETAIL: parameters: $1 = 'CONFIRMED', $2 = 'IS', $3 = '1984-10-10', $4 = '[email protected]', $5 = 's7w7j5cdm1bg', $6 = 'FEMALE', $7 = 'Terrier9', $8 = 'en', $9 = 'Russel', $10 = '\x64..6439', $11 = '\x33...3836', $12 = '+16509876945', $13 = 'USER', $14 = 'ENABLED', $15 = '2017-04-11 19:41:31.268', $16 = 'demouser9', $17 = '547', $18 = '10', $19 = '546' 
2017-04-11 12:41:32 PDT  73842 LOG: 00000: process 73842 detected deadlock while waiting for ExclusiveLock on tuple (206,43) of relation 17992 of database 16385 after 1000.114 ms 
2017-04-11 12:41:32 PDT  73842 DETAIL: Process holding the lock: 73817. Wait queue: . 
2017-04-11 12:41:32 PDT  73842 LOCATION: ProcSleep, proc.c:1415 
2017-04-11 12:41:32 PDT  73842 STATEMENT: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 
2017-04-11 12:41:32 PDT  73842 ERROR: 40P01: deadlock detected 
2017-04-11 12:41:32 PDT  73842 DETAIL: Process 73842 waits for ExclusiveLock on tuple (206,43) of relation 17992 of database 16385; blocked by process 73817. 
     Process 73817 waits for ShareLock on transaction 2716972; blocked by process 73842. 
     Process 73842: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 
2017-04-11 12:41:32 PDT  73842 HINT: See server log for query details. 
2017-04-11 12:41:32 PDT  73842 LOCATION: DeadLockReport, deadlock.c:1140 
2017-04-11 12:41:32 PDT  73842 STATEMENT: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 
2017-04-11 12:41:32 PDT  73842 ERROR: 25P02: current transaction is aborted, commands ignored until end of transaction block 
2017-04-11 12:41:32 PDT  73842 LOCATION: exec_parse_message, postgres.c:1303 
2017-04-11 12:41:32 PDT  73842 STATEMENT: SELECT NULL AS TABLE_CAT, n.nspname AS TABLE_SCHEM, c.relname AS TABLE_NAME, CASE n.nspname ~ '^pg_' OR n.nspname = 'information_schema' WHEN true THEN CASE WHEN n.nspname = 'pg_catalog' OR n.nspname = 'information_schema' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TABLE' WHEN 'v' THEN 'SYSTEM VIEW' WHEN 'i' THEN 'SYSTEM INDEX' ELSE NULL END WHEN n.nspname = 'pg_toast' THEN CASE c.relkind WHEN 'r' THEN 'SYSTEM TOAST TABLE' WHEN 'i' THEN 'SYSTEM TOAST INDEX' ELSE NULL END ELSE CASE c.relkind WHEN 'r' THEN 'TEMPORARY TABLE' WHEN 'i' THEN 'TEMPORARY INDEX' WHEN 'S' THEN 'TEMPORARY SEQUENCE' WHEN 'v' THEN 'TEMPORARY VIEW' ELSE NULL END END WHEN false THEN CASE c.relkind WHEN 'r' THEN 'TABLE' WHEN 'i' THEN 'INDEX' WHEN 'S' THEN 'SEQUENCE' WHEN 'v' THEN 'VIEW' WHEN 'c' THEN 'TYPE' WHEN 'f' THEN 'FOREIGN TABLE' WHEN 'm' THEN 'MATERIALIZED VIEW' ELSE NULL END ELSE NULL END AS TABLE_TYPE, d.description AS REMARKS FROM pg_catalog.pg_namespace n, pg_catalog.pg_class c LEFT JOIN pg_catalog.pg_description d ON (c.oid = d.objoid AND d.objsubid = 0) LEFT JOIN pg_catalog.pg_class dc ON (d.classoid=dc.oid AND dc.relname='pg_class') LEFT JOIN pg_catalog.pg_namespace dn ON (dn.oid=dc.relnamespace AND dn.nspname='pg_catalog') WHERE c.relnamespace = n.oid AND c.relname LIKE 'PROBABLYNOT' AND (false OR (c.relkind = 'r' AND n.nspname !~ '^pg_' AND n.nspname <> 'information_schema')) ORDER BY TABLE_TYPE,TABLE_SCHEM,TABLE_NAME 
2017-04-11 12:41:32 PDT  73842 LOG: 00000: execute S_11: ROLLBACK

过程2日志：

2017-04-11 12:41:31 PDT  73817 LOG: 00000: execute S_2: BEGIN 
2017-04-11 12:41:31 PDT  73817 LOG: 00000: execute S_3: select user0_.id as id1_2_0_, user0_.confirmationState as confirma2_2_0_, user0_.country_iso as country19_2_0_, user0_.created as created3_2_0_, user0_.dateOfBirth as dateOfBi4_2_0_, user0_.email as email5_2_0_, user0_.firstName as firstNam6_2_0_, user0_.gender as gender7_2_0_, user0_.lastName as lastName8_2_0_, user0_.lastUsedLocale as lastUsed9_2_0_, user0_.middleName as middleN10_2_0_, user0_.passwordHash as passwor11_2_0_, user0_.passwordSalt as passwor12_2_0_, user0_.phone as phone13_2_0_, user0_.role as role14_2_0_, user0_.signInState as signInS15_2_0_, user0_.updated as updated16_2_0_, user0_.username as usernam17_2_0_, user0_.version as version18_2_0_, country1_.iso as iso1_0_1_, country1_.iso3 as iso2_0_1_, country1_.name as name3_0_1_, country1_.nativeName as nativeNa4_0_1_, country1_.numCode as numCode5_0_1_, country1_.phoneCode as phoneCod6_0_1_ from users user0_ left outer join countries country1_ on user0_.country_iso=country1_.iso where user0_.id=$1 
2017-04-11 12:41:31 PDT  73817 DETAIL: parameters: $1 = '10' 
2017-04-11 12:41:31 PDT  73817 LOG: 00000: execute S_6: select country0_.iso as iso1_0_0_, country0_.iso3 as iso2_0_0_, country0_.name as name3_0_0_, country0_.nativeName as nativeNa4_0_0_, country0_.numCode as numCode5_0_0_, country0_.phoneCode as phoneCod6_0_0_ from countries country0_ where country0_.iso=$1 
2017-04-11 12:41:31 PDT  73817 DETAIL: parameters: $1 = 'JP' 
2017-04-11 12:41:31 PDT  73817  
2017-04-11 12:41:31 PDT  73817 LOG: 00000: execute S_5: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 
2017-04-11 12:41:31 PDT  73817 DETAIL: parameters: $1 = 'CONFIRMED', $2 = 'JP', $3 = '1984-10-10', $4 = '[email protected]', $5 = '-1kcg4facio48g', $6 = 'FEMALE', $7 = 'Terrier9', $8 = 'en', $9 = 'Russel', $10 = '\x64656d6f7573657270617373776f726439', $11 = '\x33...3836', $12 = '+16509876905', $13 = 'USER', $14 = 'ENABLED', $15 = '2017-04-11 19:41:31.188', $16 = 'demouser9', $17 = '547', $18 = '10', $19 = '546' 
2017-04-11 12:41:32 PDT  73842 DETAIL: Process holding the lock: 73817. Wait queue: . 
2017-04-11 12:41:32 PDT  73842 DETAIL: Process 73842 waits for ExclusiveLock on tuple (206,43) of relation 17992 of database 16385; blocked by process 73817. 
     Process 73817 waits for ShareLock on transaction 2716972; blocked by process 73842. 
     Process 73817: update users set confirmationState=$1, country_iso=$2, dateOfBirth=$3, email=$4, firstName=$5, gender=$6, lastName=$7, lastUsedLocale=$8, middleName=$9, passwordHash=$10, passwordSalt=$11, phone=$12, role=$13, signInState=$14, updated=$15, username=$16, version=$17 where id=$18 and version=$19 
2017-04-11 12:41:32 PDT  73817 LOG: 00000: execute S_10: ROLLBACK

用于过程1的流程为：

  1. BEGIN;
  2. SELECT * FROM users WHERE id = 10;
  3. SELECT * FROM countries; //不影响问题
  4. INSERT INTO userEvents（...，user_id，...）VALUES（...，10，...）;
  5. UPDATE users SET [..fields to update ..] WHERE id = 10 AND version = 546;
  6. COMMIT;

为处理2的流程为：

  1. BEGIN;
  2. SELECT * FROM users WHERE id = 10;
  3. UPDATE users SET [..fields to update ..] WHERE id = 10 AND version = 546;
  4. COMMIT;

是因为在第一交易获取上FK（userEvents.user_id）的排他锁为INSERT后来上UPDATE的独占锁（users.id = 10）的顺序的和（users.id = 10）和（userEvents.user_id）在更新在第二？

因为当我强迫“用户更新”“INSERT INTO userEvents”之前我没有看到死锁在高负载下了。

来源

2017-04-06 PhantomLordD7

+0

你在这些交易中还做了什么？是f.ex.触发器涉及？或者，插入另一个表中？ - 你读过这个相关的问题吗？ http://stackoverflow.com/questions/18297478/deadlock-in-postgres-on-simple-update-query – pozs

回答

0

如果两个事务试图同时更新同一行，并且同一行同时有version，那么其中一个将获取该行的锁，另一个将会阻塞。

只要第一笔交易处于活动状态，第二笔交易就无法决定是否“获得”了乐观锁。如果第一笔交易成功，第二笔交易将发现version不再匹配，并且将返回而不更新任何内容。但是，如果第一笔交易回滚，第二笔交易将获得旧版version的锁定并继续更新。与此同时，它只需等待，一旦你有交易等待，死锁场景很容易构建。

来源

2017-04-06 07:41:32

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