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Create an infrastructure for parallel computation in PostgreSQL.

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This does four basic things.  First, it provides convenience routines
to coordinate the startup and shutdown of parallel workers.  Second,
it synchronizes various pieces of state (e.g. GUCs, combo CID
mappings, transaction snapshot) from the parallel group leader to the
worker processes.  Third, it prohibits various operations that would
result in unsafe changes to that state while parallelism is active.
Finally, it propagates events that would result in an ErrorResponse,
NoticeResponse, or NotifyResponse message being sent to the client
from the parallel workers back to the master, from which they can then
be sent on to the client.

Robert Haas, Amit Kapila, Noah Misch, Rushabh Lathia, Jeevan Chalke.
Suggestions and review from Andres Freund, Heikki Linnakangas, Noah
Misch, Simon Riggs, Euler Taveira, and Jim Nasby.
This commit is contained in:
Robert Haas
2015-04-30 15:02:14 -04:00
parent 669c7d20e6
commit 924bcf4f16
37 changed files with 2499 additions and 47 deletions
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33
src/backend/libpq/pqmq.c
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@@ -16,12 +16,15 @@
#include "libpq/libpq.h"
#include "libpq/pqformat.h"
#include "libpq/pqmq.h"
#include "miscadmin.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
static shm_mq *pq_mq;
static shm_mq_handle *pq_mq_handle;
static bool pq_mq_busy = false;
static pid_t pq_mq_parallel_master_pid = 0;
static pid_t pq_mq_parallel_master_backend_id = InvalidBackendId;
static void mq_comm_reset(void);
static int mq_flush(void);
@@ -57,6 +60,18 @@ pq_redirect_to_shm_mq(shm_mq *mq, shm_mq_handle *mqh)
FrontendProtocol = PG_PROTOCOL_LATEST;
}
/*
* Arrange to SendProcSignal() to the parallel master each time we transmit
* message data via the shm_mq.
*/
void
pq_set_parallel_master(pid_t pid, BackendId backend_id)
{
Assert(PqCommMethods == &PqCommMqMethods);
pq_mq_parallel_master_pid = pid;
pq_mq_parallel_master_backend_id = backend_id;
}
static void
mq_comm_reset(void)
{
@@ -120,7 +135,23 @@ mq_putmessage(char msgtype, const char *s, size_t len)
iov[1].len = len;
Assert(pq_mq_handle != NULL);
result = shm_mq_sendv(pq_mq_handle, iov, 2, false);
for (;;)
{
result = shm_mq_sendv(pq_mq_handle, iov, 2, true);
if (pq_mq_parallel_master_pid != 0)
SendProcSignal(pq_mq_parallel_master_pid,
PROCSIG_PARALLEL_MESSAGE,
pq_mq_parallel_master_backend_id);
if (result != SHM_MQ_WOULD_BLOCK)
break;
WaitLatch(&MyProc->procLatch, WL_LATCH_SET, 0);
CHECK_FOR_INTERRUPTS();
ResetLatch(&MyProc->procLatch);
}
pq_mq_busy = false;