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Deprecate enable_deadlock_prevention flag 

Now that we already have the necessary infrastructure for detecting
distributed deadlocks. Thus, we don't need enable_deadlock_prevention
which is purely intended for preventing some forms of distributed
deadlocks.
pull/1529/head
Onder Kalaci 2017-08-11 11:36:31 +03:00
parent a333c9f16c
commit be4fc45c03
6 changed files with 58 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
src/backend/distributed/executor/multi_router_executor.c
View File

@ -70,6 +70,8 @@
/* controls use of locks to enforce safe commutativity */
bool AllModificationsCommutative = false;
/* we've deprecated this flag, keeping here for some time not to break existing users */
bool EnableDeadlockPrevention = true;
/* functions needed during run phase */
@ -79,8 +81,7 @@ static ShardPlacementAccess * CreatePlacementAccess(ShardPlacement *placement,
static void ExecuteSingleModifyTask(CitusScanState *scanState, Task *task,
bool expectResults);
static void ExecuteSingleSelectTask(CitusScanState *scanState, Task *task);
static List * GetModifyConnections(Task *task, bool markCritical,
bool startedInTransaction);
static List * GetModifyConnections(Task *task, bool markCritical);
static void ExecuteMultipleTasks(CitusScanState *scanState, List *taskList,
bool isModificationQuery, bool expectResults);
static int64 ExecuteModifyTasks(List *taskList, bool expectResults,
@ -680,8 +681,6 @@ ExecuteSingleModifyTask(CitusScanState *scanState, Task *task, bool expectResult
char *queryString = task->queryString;
bool taskRequiresTwoPhaseCommit = (task->replicationModel == REPLICATION_MODEL_2PC);
bool startedInTransaction =
InCoordinatedTransaction() && XactModificationLevel == XACT_MODIFICATION_DATA;
/*
* Modifications for reference tables are always done using 2PC. First
@ -711,9 +710,7 @@ ExecuteSingleModifyTask(CitusScanState *scanState, Task *task, bool expectResult
* establish the connection, mark as critical (when modifying reference
* table) and start a transaction (when in a transaction).
*/
connectionList = GetModifyConnections(task,
taskRequiresTwoPhaseCommit,
startedInTransaction);
connectionList = GetModifyConnections(task, taskRequiresTwoPhaseCommit);
/* prevent replicas of the same shard from diverging */
AcquireExecutorShardLock(task, operation);
@ -809,12 +806,10 @@ ExecuteSingleModifyTask(CitusScanState *scanState, Task *task, bool expectResult
* modify commands on the placements in tasPlacementList. If necessary remote
* transactions are started.
*
* If markCritical is true remote transactions are marked as critical. If
* noNewTransactions is true, this function errors out if there's no
* transaction in progress.
* If markCritical is true remote transactions are marked as critical.
*/
static List *
GetModifyConnections(Task *task, bool markCritical, bool noNewTransactions)
GetModifyConnections(Task *task, bool markCritical)
{
List *taskPlacementList = task->taskPlacementList;
ListCell *taskPlacementCell = NULL;
@ -844,22 +839,17 @@ GetModifyConnections(Task *task, bool markCritical, bool noNewTransactions)
NULL);
/*
* If already in a transaction, disallow expanding set of remote
* transactions. That prevents some forms of distributed deadlocks.
* If we're expanding the set nodes that participate in the distributed
* transaction, conform to MultiShardCommitProtocol.
*/
if (noNewTransactions)
if (MultiShardCommitProtocol == COMMIT_PROTOCOL_2PC &&
InCoordinatedTransaction() &&
XactModificationLevel == XACT_MODIFICATION_DATA)
{
RemoteTransaction *transaction = &multiConnection->remoteTransaction;
if (EnableDeadlockPrevention &&
transaction->transactionState == REMOTE_TRANS_INVALID)
if (transaction->transactionState == REMOTE_TRANS_INVALID)
{
ereport(ERROR, (errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
errmsg("no transaction participant matches %s:%d",
taskPlacement->nodeName, taskPlacement->nodePort),
errdetail("Transactions which modify distributed tables "
"may only target nodes affected by the "
"modification command which began the transaction.")));
CoordinatedTransactionUse2PC();
}
}

15
src/backend/distributed/shared_library_init.c
View File

@ -59,6 +59,7 @@ void _PG_init(void);
static void CreateRequiredDirectories(void);
static void RegisterCitusConfigVariables(void);
static void WarningForEnableDeadlockPrevention(bool newval, void *extra);
static void NormalizeWorkerListPath(void);
@ -379,7 +380,7 @@ RegisterCitusConfigVariables(void)
true,
PGC_USERSET,
GUC_NO_SHOW_ALL,
NULL, NULL, NULL);
NULL, WarningForEnableDeadlockPrevention, NULL);
DefineCustomBoolVariable(
"citus.enable_ddl_propagation",
@ -737,6 +738,18 @@ RegisterCitusConfigVariables(void)
}
/*
* Inform the users about the deprecated flag.
*/
static void
WarningForEnableDeadlockPrevention(bool newval, void *extra)
{
ereport(WARNING, (errcode(ERRCODE_WARNING_DEPRECATED_FEATURE),
errmsg("citus.enable_deadlock_prevention is deprecated and it has "
"no effect. The flag will be removed in the next release.")));
}
/*
* NormalizeWorkerListPath converts the path configured via
* citus.worker_list_file into an absolute path, falling back to the default

46
src/test/regress/expected/multi_modifying_xacts.out
View File

@ -145,18 +145,18 @@ SELECT * FROM researchers, labs WHERE labs.id = researchers.lab_id;
8 | 5 | Douglas Engelbart | 5 | Los Alamos
(1 row)
-- but not the other way around (would require expanding xact participants)...
-- and the other way around is also allowed
BEGIN;
INSERT INTO labs VALUES (6, 'Bell Labs');
INSERT INTO researchers VALUES (9, 6, 'Leslie Lamport');
ERROR: no transaction participant matches localhost:57638
DETAIL: Transactions which modify distributed tables may only target nodes affected by the modification command which began the transaction.
COMMIT;
-- unless we disable deadlock prevention
-- we should be able to expand the transaction participants
BEGIN;
SET citus.enable_deadlock_prevention TO off;
INSERT INTO labs VALUES (6, 'Bell Labs');
INSERT INTO researchers VALUES (9, 6, 'Leslie Lamport');
ERROR: duplicate key value violates unique constraint "avoid_name_confusion_idx_1200001"
DETAIL: Key (lab_id, name)=(6, Leslie Lamport) already exists.
CONTEXT: while executing command on localhost:57638
ABORT;
-- SELECTs may occur after a modification: First check that selecting
-- from the modified node works.
@ -165,7 +165,7 @@ INSERT INTO labs VALUES (6, 'Bell Labs');
SELECT count(*) FROM researchers WHERE lab_id = 6;
count
-------
0
1
(1 row)
ABORT;
@ -181,7 +181,7 @@ INSERT INTO labs VALUES (6, 'Bell Labs');
SELECT count(*) FROM researchers WHERE lab_id = 6;
count
-------
0
1
(1 row)
ABORT;
@ -204,9 +204,10 @@ SELECT "Column", "Type", "Modifiers" FROM table_desc WHERE relid='public.labs'::
(2 rows)
SELECT * FROM labs WHERE id = 6;
id | name
----+------
(0 rows)
id | name
----+-----------
6 | Bell Labs
(1 row)
-- COPY can happen after single row INSERT
BEGIN;
@ -272,9 +273,10 @@ DETAIL: Key (lab_id, name)=(6, 'Bjarne Stroustrup') already exists.
COMMIT;
-- verify rollback
SELECT * FROM researchers WHERE lab_id = 6;
id | lab_id | name
----+--------+------
(0 rows)
id | lab_id | name
----+--------+----------------
9 | 6 | Leslie Lamport
(1 row)
SELECT count(*) FROM pg_dist_transaction;
count
@ -299,9 +301,10 @@ DETAIL: Key (lab_id, name)=(6, 'Bjarne Stroustrup') already exists.
COMMIT;
-- verify rollback
SELECT * FROM researchers WHERE lab_id = 6;
id | lab_id | name
----+--------+------
(0 rows)
id | lab_id | name
----+--------+----------------
9 | 6 | Leslie Lamport
(1 row)
SELECT count(*) FROM pg_dist_transaction;
count
@ -317,9 +320,10 @@ COMMIT;
SELECT * FROM researchers WHERE lab_id = 6;
id | lab_id | name
----+--------+----------------------
9 | 6 | Leslie Lamport
17 | 6 | 'Bjarne Stroustrup'
18 | 6 | 'Dennis Ritchie'
(2 rows)
(3 rows)
-- verify 2pc
SELECT count(*) FROM pg_dist_transaction;
@ -376,9 +380,10 @@ ERROR: could not commit transaction on any active node
SELECT * FROM researchers WHERE lab_id = 6;
id | lab_id | name
----+--------+----------------------
9 | 6 | Leslie Lamport
17 | 6 | 'Bjarne Stroustrup'
18 | 6 | 'Dennis Ritchie'
(2 rows)
(3 rows)
-- cleanup triggers and the function
SELECT * from run_command_on_placements('researchers', 'drop trigger reject_large_researcher_id on %s')
@ -429,7 +434,7 @@ ALTER TABLE labs ADD COLUMN motto text;
SELECT master_modify_multiple_shards('DELETE FROM labs');
master_modify_multiple_shards
-------------------------------
7
8
(1 row)
ALTER TABLE labs ADD COLUMN score float;
@ -909,16 +914,13 @@ SELECT create_distributed_table('hash_modifying_xacts', 'key');
BEGIN;
INSERT INTO hash_modifying_xacts VALUES (1, 1);
INSERT INTO reference_modifying_xacts VALUES (10, 10);
ERROR: no transaction participant matches localhost:57638
COMMIT;
-- it is allowed when turning off deadlock prevention
BEGIN;
SET citus.enable_deadlock_prevention TO off;
INSERT INTO hash_modifying_xacts VALUES (1, 1);
INSERT INTO reference_modifying_xacts VALUES (10, 10);
ABORT;
BEGIN;
SET citus.enable_deadlock_prevention TO off;
INSERT INTO hash_modifying_xacts VALUES (1, 1);
INSERT INTO hash_modifying_xacts VALUES (2, 2);
ABORT;

10
src/test/regress/expected/multi_mx_modifying_xacts.out
View File

@ -136,12 +136,10 @@ SELECT * FROM researchers_mx, labs_mx WHERE labs_mx.id = researchers_mx.lab_id;
8 | 5 | Douglas Engelbart | 5 | Los Alamos
(1 row)
-- but not the other way around (would require expanding xact participants)...
-- and the other way around is also allowed
BEGIN;
INSERT INTO labs_mx VALUES (6, 'Bell labs_mx');
INSERT INTO researchers_mx VALUES (9, 6, 'Leslie Lamport');
ERROR: no transaction participant matches localhost:57638
DETAIL: Transactions which modify distributed tables may only target nodes affected by the modification command which began the transaction.
COMMIT;
-- have the same test on the other worker node
\c - - - :worker_2_port
@ -159,12 +157,10 @@ SELECT * FROM researchers_mx, labs_mx WHERE labs_mx.id = researchers_mx.lab_id;
8 | 5 | Douglas Engelbart | 5 | Los Alamos
(4 rows)
-- but not the other way around (would require expanding xact participants)...
-- and the other way around is also allowed
BEGIN;
INSERT INTO labs_mx VALUES (6, 'Bell labs_mx');
INSERT INTO researchers_mx VALUES (9, 6, 'Leslie Lamport');
ERROR: no transaction participant matches localhost:57638
DETAIL: Transactions which modify distributed tables may only target nodes affected by the modification command which began the transaction.
COMMIT;
-- switch back to the worker node
\c - - - :worker_1_port
@ -175,7 +171,7 @@ INSERT INTO labs_mx VALUES (6, 'Bell labs_mx');
SELECT count(*) FROM researchers_mx WHERE lab_id = 6;
count
-------
0
2
(1 row)
ABORT;

7
src/test/regress/sql/multi_modifying_xacts.sql
View File

@ -113,15 +113,14 @@ COMMIT;
SELECT * FROM researchers, labs WHERE labs.id = researchers.lab_id;
-- but not the other way around (would require expanding xact participants)...
-- and the other way around is also allowed
BEGIN;
INSERT INTO labs VALUES (6, 'Bell Labs');
INSERT INTO researchers VALUES (9, 6, 'Leslie Lamport');
COMMIT;
-- unless we disable deadlock prevention
-- we should be able to expand the transaction participants
BEGIN;
SET citus.enable_deadlock_prevention TO off;
INSERT INTO labs VALUES (6, 'Bell Labs');
INSERT INTO researchers VALUES (9, 6, 'Leslie Lamport');
ABORT;
@ -703,13 +702,11 @@ COMMIT;
-- it is allowed when turning off deadlock prevention
BEGIN;
SET citus.enable_deadlock_prevention TO off;
INSERT INTO hash_modifying_xacts VALUES (1, 1);
INSERT INTO reference_modifying_xacts VALUES (10, 10);
ABORT;
BEGIN;
SET citus.enable_deadlock_prevention TO off;
INSERT INTO hash_modifying_xacts VALUES (1, 1);
INSERT INTO hash_modifying_xacts VALUES (2, 2);
ABORT;

4
src/test/regress/sql/multi_mx_modifying_xacts.sql
View File

@ -118,7 +118,7 @@ COMMIT;
SELECT * FROM researchers_mx, labs_mx WHERE labs_mx.id = researchers_mx.lab_id;
-- but not the other way around (would require expanding xact participants)...
-- and the other way around is also allowed
BEGIN;
INSERT INTO labs_mx VALUES (6, 'Bell labs_mx');
INSERT INTO researchers_mx VALUES (9, 6, 'Leslie Lamport');
@ -134,7 +134,7 @@ COMMIT;
SELECT * FROM researchers_mx, labs_mx WHERE labs_mx.id = researchers_mx.lab_id;
-- but not the other way around (would require expanding xact participants)...
-- and the other way around is also allowed
BEGIN;
INSERT INTO labs_mx VALUES (6, 'Bell labs_mx');
INSERT INTO researchers_mx VALUES (9, 6, 'Leslie Lamport');