diff options
Diffstat (limited to 'src/backend/postmaster')
| -rw-r--r-- | src/backend/postmaster/postmaster.c | 46 |
1 files changed, 33 insertions, 13 deletions
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index 688ad439ed..7a4b6cb7f8 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -409,7 +409,7 @@ static void SendNegotiateProtocolVersion(List *unrecognized_protocol_options); static void processCancelRequest(Port *port, void *pkt); static int initMasks(fd_set *rmask); static void report_fork_failure_to_client(Port *port, int errnum); -static CAC_state canAcceptConnections(void); +static CAC_state canAcceptConnections(int backend_type); static bool RandomCancelKey(int32 *cancel_key); static void signal_child(pid_t pid, int signal); static bool SignalSomeChildren(int signal, int targets); @@ -2384,16 +2384,21 @@ processCancelRequest(Port *port, void *pkt) } /* - * canAcceptConnections --- check to see if database state allows connections. + * canAcceptConnections --- check to see if database state allows connections + * of the specified type. backend_type can be BACKEND_TYPE_NORMAL, + * BACKEND_TYPE_AUTOVAC, or BACKEND_TYPE_BGWORKER. (Note that we don't yet + * know whether a NORMAL connection might turn into a walsender.) */ static CAC_state -canAcceptConnections(void) +canAcceptConnections(int backend_type) { CAC_state result = CAC_OK; /* * Can't start backends when in startup/shutdown/inconsistent recovery - * state. + * state. We treat autovac workers the same as user backends for this + * purpose. However, bgworkers are excluded from this test; we expect + * bgworker_should_start_now() decided whether the DB state allows them. * * In state PM_WAIT_BACKUP only superusers can connect (this must be * allowed so that a superuser can end online backup mode); we return @@ -2401,7 +2406,8 @@ canAcceptConnections(void) * that neither CAC_OK nor CAC_WAITBACKUP can safely be returned until we * have checked for too many children. */ - if (pmState != PM_RUN) + if (pmState != PM_RUN && + backend_type != BACKEND_TYPE_BGWORKER) { if (pmState == PM_WAIT_BACKUP) result = CAC_WAITBACKUP; /* allow superusers only */ @@ -2421,9 +2427,9 @@ canAcceptConnections(void) /* * Don't start too many children. * - * We allow more connections than we can have backends here because some + * We allow more connections here than we can have backends because some * might still be authenticating; they might fail auth, or some existing - * backend might exit before the auth cycle is completed. The exact + * backend might exit before the auth cycle is completed. The exact * MaxBackends limit is enforced when a new backend tries to join the * shared-inval backend array. * @@ -4086,7 +4092,7 @@ BackendStartup(Port *port) bn->cancel_key = MyCancelKey; /* Pass down canAcceptConnections state */ - port->canAcceptConnections = canAcceptConnections(); + port->canAcceptConnections = canAcceptConnections(BACKEND_TYPE_NORMAL); bn->dead_end = (port->canAcceptConnections != CAC_OK && port->canAcceptConnections != CAC_WAITBACKUP); @@ -5458,7 +5464,7 @@ StartAutovacuumWorker(void) * we have to check to avoid race-condition problems during DB state * changes. */ - if (canAcceptConnections() == CAC_OK) + if (canAcceptConnections(BACKEND_TYPE_AUTOVAC) == CAC_OK) { /* * Compute the cancel key that will be assigned to this session. We @@ -5703,12 +5709,13 @@ do_start_bgworker(RegisteredBgWorker *rw) /* * Allocate and assign the Backend element. Note we must do this before - * forking, so that we can handle out of memory properly. + * forking, so that we can handle failures (out of memory or child-process + * slots) cleanly. * * Treat failure as though the worker had crashed. That way, the - * postmaster will wait a bit before attempting to start it again; if it - * tried again right away, most likely it'd find itself repeating the - * out-of-memory or fork failure condition. + * postmaster will wait a bit before attempting to start it again; if we + * tried again right away, most likely we'd find ourselves hitting the + * same resource-exhaustion condition. */ if (!assign_backendlist_entry(rw)) { @@ -5835,6 +5842,19 @@ assign_backendlist_entry(RegisteredBgWorker *rw) Backend *bn; /* + * Check that database state allows another connection. Currently the + * only possible failure is CAC_TOOMANY, so we just log an error message + * based on that rather than checking the error code precisely. + */ + if (canAcceptConnections(BACKEND_TYPE_BGWORKER) != CAC_OK) + { + ereport(LOG, + (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED), + errmsg("no slot available for new worker process"))); + return false; + } + + /* * Compute the cancel key that will be assigned to this session. We * probably don't need cancel keys for background workers, but we'd better * have something random in the field to prevent unfriendly people from |