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Make sure that lost connections are handled properly 

Before this patch, when a connection is lost, we'd have the following
situation:

    - Pop a task execution from readyQueue
    - Lost connection
    - Fail the session/pool. -> This step was not acting properly
      because we've popped the task, but not set to session->currentTask
      yet

After the patch:

    - Pop a task execution from readyQueue
    - Immediately set it to session->currentTask
    - Lost connection
    - Fail the session/pool. -> At this step, failing the
      session would trigger query failures (or failovers)
      properly.
pull/2942/head
Onder Kalaci 2019-09-10 15:03:08 +02:00
parent d99deab7d9
commit 485189c0b6
1 changed files with 25 additions and 6 deletions
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31
src/backend/distributed/executor/adaptive_executor.c
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@ -2412,6 +2412,7 @@ TransactionStateMachine(WorkerSession *session)
else
{
TaskPlacementExecution *placementExecution = NULL;
bool placementExecutionStarted = false;
placementExecution = PopPlacementExecution(session);
if (placementExecution == NULL)
@ -2425,7 +2426,17 @@ TransactionStateMachine(WorkerSession *session)
break;
}
StartPlacementExecutionOnSession(placementExecution, session);
placementExecutionStarted =
StartPlacementExecutionOnSession(placementExecution, session);
if (!placementExecutionStarted)
{
/* no need to continue, connection is lost */
Assert(session->connection->connectionState ==
MULTI_CONNECTION_LOST);
return;
}
transaction->transactionState = REMOTE_TRANS_SENT_COMMAND;
}
@ -2494,6 +2505,7 @@ TransactionStateMachine(WorkerSession *session)
case REMOTE_TRANS_STARTED:
{
TaskPlacementExecution *placementExecution = NULL;
bool placementExecutionStarted = false;
placementExecution = PopPlacementExecution(session);
if (placementExecution == NULL)
@ -2503,7 +2515,16 @@ TransactionStateMachine(WorkerSession *session)
break;
}
StartPlacementExecutionOnSession(placementExecution, session);
placementExecutionStarted =
StartPlacementExecutionOnSession(placementExecution, session);
if (!placementExecutionStarted)
{
/* no need to continue, connection is lost */
Assert(session->connection->connectionState == MULTI_CONNECTION_LOST);
return;
}
transaction->transactionState = REMOTE_TRANS_SENT_COMMAND;
break;
}
@ -2539,7 +2560,6 @@ TransactionStateMachine(WorkerSession *session)
}
}
}
/* iterate in case we can perform multiple transitions at once */
while (transaction->transactionState != currentState);
}
@ -2748,6 +2768,8 @@ StartPlacementExecutionOnSession(TaskPlacementExecution *placementExecution,
/* connection is going to be in use */
workerPool->idleConnectionCount--;
session->currentTask = placementExecution;
placementExecution->executionState = PLACEMENT_EXECUTION_RUNNING;
if (paramListInfo != NULL)
{
@ -2781,9 +2803,6 @@ StartPlacementExecutionOnSession(TaskPlacementExecution *placementExecution,
return false;
}
session->currentTask = placementExecution;
placementExecution->executionState = PLACEMENT_EXECUTION_RUNNING;
return true;
}