fix

Author: reshke

src/backend/postmaster/postmaster.c

@@ -239,6 +239,8 @@ int			ReservedBackends;
 #define MAXLISTEN	64
 static pgsocket ListenSocket[MAXLISTEN];
 
+unsigned char *ForkLock = NULL;
+
 /*
  * Set by the -o option
  */
@@ -4498,6 +4500,9 @@ BackendStartup(Port *port)
 #ifdef EXEC_BACKEND
 	pid = backend_forkexec(port);
 #else							/* !EXEC_BACKEND */
+
+	if (gp_enable_fork_lock)
+		SpinLockAcquire(ForkLock);
 	pid = fork_process();
 	if (pid == 0)				/* child */
 	{
@@ -4522,6 +4527,8 @@ BackendStartup(Port *port)
 
 		/* Perform additional initialization and collect startup packet */
 		BackendInitialize(port);
+		if (gp_enable_fork_lock)
+			SpinLockRelease(ForkLock);
 
 		/* And run the backend */
 		BackendRun(port);

src/backend/storage/ipc/ipci.c

@@ -372,6 +372,11 @@ CreateSharedMemoryAndSemaphores(int port)
 
 	if (gp_enable_resqueue_priority)
 		BackoffStateInit();
+	if (gp_enable_fork_lock) {
+			/* Create ProcStructLock spinlock, too */
+		ForkLock = (slock_t *) ShmemAlloc(sizeof(slock_t));
+		SpinLockInit(ForkLock);
+	}
 
 	/* Initialize dynamic shared memory facilities. */
 	if (!IsUnderPostmaster)

src/backend/utils/misc/guc_gp.c

@@ -215,6 +215,7 @@ static char *gp_resource_manager_str;
 
 /* Backoff-related GUCs */
 bool		gp_enable_resqueue_priority;
+bool		gp_enable_fork_lock;
 int			gp_resqueue_priority_local_interval;
 int			gp_resqueue_priority_sweeper_interval;
 int			gp_resqueue_priority_inactivity_timeout;
@@ -1744,6 +1745,16 @@ struct config_bool ConfigureNamesBool_gp[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"gp_enable_fork_lock", PGC_POSTMASTER, RESOURCES_MGM,
+			gettext_noop("Enables priority scheduling."),
+			NULL
+		},
+		&gp_enable_fork_lock,
+		true,
+		NULL, NULL, NULL
+	},
+
 	{
 		{"debug_resource_group", PGC_USERSET, DEVELOPER_OPTIONS,
 			gettext_noop("Prints resource groups debug logs."),

src/include/postmaster/backoff.h

@@ -12,6 +12,7 @@
 
 /* GUCs */
 extern bool gp_enable_resqueue_priority;
+extern bool gp_enable_fork_lock;
 extern int gp_resqueue_priority_local_interval;
 extern int gp_resqueue_priority_sweeper_interval;
 extern int gp_resqueue_priority_inactivity_timeout;

src/include/postmaster/postmaster.h

@@ -55,6 +55,8 @@ extern int	postmaster_alive_fds[2];
 extern const char *progname;
 extern PGDLLIMPORT const char *progname;
 
+extern unsigned char *ForkLock;
+
 extern void PostmasterMain(int argc, char *argv[]) __attribute__((noreturn));
 extern void ClosePostmasterPorts(bool am_syslogger);
 

src/include/utils/sync_guc_name.h

@@ -23,6 +23,7 @@
 		"gp_enable_mk_sort",
 		"gp_enable_motion_mk_sort",
 		"gp_enable_segment_copy_checking",
+		"gp_enable_fork_lock",
 		"gp_external_enable_filter_pushdown",
 		"gp_gpperfmon_send_interval",
 		"gp_hashagg_default_nbatches",