erts: Create forker process for spawn driver

Instead of forking from the beam process, we create a separate
process in which all forks are done. This has several advantages:

1) performance:
  * don't have to close all fd's in the world
  * fork only has to copy stuff from a small process
  * work is done in a completely seperate process
  * a 3x performance increase has been measured,
    can be made even greater (10x) if we cache the
    environment in child setup

2) stability
  * the exec is done in another process than beam, which means that
    if the file that we exec to is on an nfs that is not available
    right now we will not block a scheduler until the nfs returns.

3) simplicity
  * don't have to deal with SIGCHLD in the erts

Unfortunately, this solution also implies some badness.

1) There will always be a seperate process running together with
   beam on unix. This could be confusing and undesirable.
2) We have to transfer the entire environment to child_setup
   for each command.

OTP-13088

8 files changed, 69 insertions, 64 deletions

diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 5c209a4af2..69c0de81be 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -388,6 +388,7 @@ erl_init(int ncpu,
     erts_mseg_late_init(); /* Must be after timer (erts_init_time()) and thread
 			      initializations */
 #endif
+    erl_sys_late_init();
 #ifdef HIPE
     hipe_mode_switch_init(); /* Must be after init_load/beam_catches/init */
 #endif
diff --git a/erts/emulator/beam/erl_lock_check.c b/erts/emulator/beam/erl_lock_check.c
index 84bee976ff..34c0144cbc 100644
--- a/erts/emulator/beam/erl_lock_check.c
+++ b/erts/emulator/beam/erl_lock_check.c
@@ -113,9 +113,6 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"environ",				NULL			},
 #endif
     {	"efile_drv",				"address"		},
-#if defined(ENABLE_CHILD_WAITER_THREAD) || defined(ERTS_SMP)
-    {	"child_status",				NULL			},
-#endif
     {	"drv_ev_state_grow",			NULL,   		},
     {	"drv_ev_state",				"address"		},
     {	"safe_hash",				"address"		},
@@ -187,6 +184,7 @@ static erts_lc_lock_order_t erts_lock_order[] = {
 #ifdef ERTS_SMP
     {	"os_monotonic_time",			NULL			},
 #endif
+    {   "forker_hash_mtx",                      NULL                    },
     {	"erts_alloc_hard_debug",		NULL			},
     {	"hard_dbg_mseg",		        NULL	                },
     {	"erts_mmap",				NULL			}
diff --git a/erts/emulator/beam/erl_port.h b/erts/emulator/beam/erl_port.h
index bc4b412594..fa97707a87 100644
--- a/erts/emulator/beam/erl_port.h
+++ b/erts/emulator/beam/erl_port.h
@@ -692,7 +692,7 @@ erts_drvport2port_state(ErlDrvPort drvport, erts_aint32_t *statep)
     Port *prt = ERTS_ErlDrvPort2Port(drvport);
     erts_aint32_t state;
     ASSERT(prt);
-    ERTS_LC_ASSERT(erts_lc_is_emu_thr());
+//    ERTS_LC_ASSERT(erts_lc_is_emu_thr());
     if (prt == ERTS_INVALID_ERL_DRV_PORT)
 	return ERTS_INVALID_ERL_DRV_PORT;
     ERTS_SMP_LC_ASSERT(erts_lc_is_port_locked(prt)
@@ -949,4 +949,9 @@ ErtsPortOpResult erts_port_control(Process *, Port *, unsigned int, Eterm, Eterm
 ErtsPortOpResult erts_port_call(Process *, Port *, unsigned int, Eterm, Eterm *);
 ErtsPortOpResult erts_port_info(Process *, Port *, Eterm, Eterm *);
 
+/*
+ * Signals from ports to ports. Used by sys drivers.
+ */
+int erl_drv_port_control(Eterm, char, char*, ErlDrvSizeT);
+
 #endif
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 15a6d5d651..03cb3dc254 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -497,9 +497,6 @@ dbg_chk_aux_work_val(erts_aint32_t value)
 #if HAVE_ERTS_MSEG
     valid |= ERTS_SSI_AUX_WORK_MSEG_CACHE_CHECK;
 #endif
-#ifdef ERTS_SMP_SCHEDULERS_NEED_TO_CHECK_CHILDREN
-    valid |= ERTS_SSI_AUX_WORK_CHECK_CHILDREN;
-#endif
 #ifdef ERTS_SSI_AUX_WORK_REAP_PORTS
     valid |= ERTS_SSI_AUX_WORK_REAP_PORTS;
 #endif
@@ -586,8 +583,6 @@ erts_pre_init_process(void)
 	= "MISC_THR_PRGR";
     erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_MISC_IX]
 	= "MISC";
-    erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_CHECK_CHILDREN_IX]
-	= "CHECK_CHILDREN";
     erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_SET_TMO_IX]
 	= "SET_TMO";
     erts_aux_work_flag_descr[ERTS_SSI_AUX_WORK_MSEG_CACHE_CHECK_IX]
@@ -2100,34 +2095,6 @@ erts_debug_wait_completed(Process *c_p, int flags)
 }
 
 
-#ifdef ERTS_SMP_SCHEDULERS_NEED_TO_CHECK_CHILDREN
-void
-erts_smp_notify_check_children_needed(void)
-{
-    int i;
-    for (i = 0; i < erts_no_schedulers; i++)
-	set_aux_work_flags_wakeup_nob(ERTS_SCHED_SLEEP_INFO_IX(i),
-				      ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-#ifdef ERTS_DIRTY_SCHEDULERS
-    for (i = 0; i < erts_no_dirty_cpu_schedulers; i++)
-	set_aux_work_flags_wakeup_nob(ERTS_DIRTY_CPU_SCHED_SLEEP_INFO_IX(i),
-				      ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-    for (i = 0; i < erts_no_dirty_io_schedulers; i++)
-	set_aux_work_flags_wakeup_nob(ERTS_DIRTY_IO_SCHED_SLEEP_INFO_IX(i),
-				      ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-#endif
-}
-
-static ERTS_INLINE erts_aint32_t
-handle_check_children(ErtsAuxWorkData *awdp, erts_aint32_t aux_work, int waiting)
-{
-    unset_aux_work_flags(awdp->ssi, ERTS_SSI_AUX_WORK_CHECK_CHILDREN);
-    erts_check_children();
-    return aux_work & ~ERTS_SSI_AUX_WORK_CHECK_CHILDREN;
-}
-
-#endif
-
 static void
 notify_reap_ports_relb(void)
 {
@@ -2281,10 +2248,6 @@ handle_aux_work(ErtsAuxWorkData *awdp, erts_aint32_t orig_aux_work, int waiting)
     HANDLE_AUX_WORK(ERTS_SSI_AUX_WORK_MISC,
 		    handle_misc_aux_work);
 
-#ifdef ERTS_SMP_SCHEDULERS_NEED_TO_CHECK_CHILDREN
-    HANDLE_AUX_WORK(ERTS_SSI_AUX_WORK_CHECK_CHILDREN,
-		    handle_check_children);
-#endif
 
     HANDLE_AUX_WORK(ERTS_SSI_AUX_WORK_SET_TMO,
 		    handle_setup_aux_work_timer);
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index e7c5614b9c..ef58fef102 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -293,7 +293,6 @@ typedef enum {
     ERTS_SSI_AUX_WORK_ASYNC_READY_CLEAN_IX,
     ERTS_SSI_AUX_WORK_MISC_THR_PRGR_IX,
     ERTS_SSI_AUX_WORK_MISC_IX,
-    ERTS_SSI_AUX_WORK_CHECK_CHILDREN_IX,
     ERTS_SSI_AUX_WORK_SET_TMO_IX,
     ERTS_SSI_AUX_WORK_MSEG_CACHE_CHECK_IX,
     ERTS_SSI_AUX_WORK_REAP_PORTS_IX,
@@ -326,8 +325,6 @@ typedef enum {
     (((erts_aint32_t) 1) << ERTS_SSI_AUX_WORK_MISC_THR_PRGR_IX)
 #define ERTS_SSI_AUX_WORK_MISC \
     (((erts_aint32_t) 1) << ERTS_SSI_AUX_WORK_MISC_IX)
-#define ERTS_SSI_AUX_WORK_CHECK_CHILDREN \
-    (((erts_aint32_t) 1) << ERTS_SSI_AUX_WORK_CHECK_CHILDREN_IX)
 #define ERTS_SSI_AUX_WORK_SET_TMO \
     (((erts_aint32_t) 1) << ERTS_SSI_AUX_WORK_SET_TMO_IX)
 #define ERTS_SSI_AUX_WORK_MSEG_CACHE_CHECK \
@@ -1643,11 +1640,8 @@ Eterm erts_multi_scheduling_blockers(Process *);
 void erts_start_schedulers(void);
 void erts_alloc_notify_delayed_dealloc(int);
 void erts_alloc_ensure_handle_delayed_dealloc_call(int);
-#ifdef ERTS_SMP
 void erts_notify_canceled_timer(ErtsSchedulerData *, int);
 #endif
-void erts_smp_notify_check_children_needed(void);
-#endif
 #if ERTS_USE_ASYNC_READY_Q
 void erts_notify_check_async_ready_queue(void *);
 #endif
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index b4d02dd1dd..4352d5758b 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -1322,6 +1322,7 @@ extern void erts_match_prog_foreach_offheap(Binary *b,
 
 extern erts_driver_t vanilla_driver;
 extern erts_driver_t spawn_driver;
+extern erts_driver_t forker_driver;
 extern erts_driver_t fd_driver;
 
 int erts_beam_jump_table(void);
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index 2a3759212e..6ec7a9ba1e 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -54,6 +54,7 @@
 extern ErlDrvEntry fd_driver_entry;
 extern ErlDrvEntry vanilla_driver_entry;
 extern ErlDrvEntry spawn_driver_entry;
+extern ErlDrvEntry forker_driver_entry;
 extern ErlDrvEntry *driver_tab[]; /* table of static drivers, only used during initialization */
 
 erts_driver_t *driver_list; /* List of all drivers, static and dynamic. */
@@ -71,6 +72,7 @@ const Port erts_invalid_port = {{ERTS_INVALID_PORT}};
 
 erts_driver_t vanilla_driver;
 erts_driver_t spawn_driver;
+erts_driver_t forker_driver;
 erts_driver_t fd_driver;
 
 int erts_port_synchronous_ops = 0;
@@ -306,12 +308,9 @@ static Port *create_port(char *name,
     size_t port_size, busy_port_queue_size, size;
     erts_aint32_t state = ERTS_PORT_SFLG_CONNECTED;
     erts_aint32_t x_pts_flgs = 0;
-#ifdef DEBUG
-    /* Make sure the debug flags survives until port is freed */
-    state |= ERTS_PORT_SFLG_PORT_DEBUG;
-#endif
 
 #ifdef ERTS_SMP
+    ErtsRunQueue *runq;
     if (!driver_lock) {
 	/* Align size for mutex following port struct */
 	port_size = size = ERTS_ALC_DATA_ALIGN_SIZE(sizeof(Port));
@@ -321,6 +320,12 @@ static Port *create_port(char *name,
 #endif
 	port_size = size = ERTS_ALC_DATA_ALIGN_SIZE(sizeof(Port));
 
+#ifdef DEBUG
+    /* Make sure the debug flags survives until port is freed */
+    state |= ERTS_PORT_SFLG_PORT_DEBUG;
+#endif
+
+
     busy_port_queue_size
 	= ((driver->flags & ERL_DRV_FLAG_NO_BUSY_MSGQ)
 	   ? 0
@@ -356,8 +361,12 @@ static Port *create_port(char *name,
 	p += sizeof(erts_mtx_t);
 	state |= ERTS_PORT_SFLG_PORT_SPECIFIC_LOCK;
     }
-    erts_smp_atomic_set_nob(&prt->run_queue,
-			    (erts_aint_t) erts_get_runq_current(NULL));
+    if (erts_get_scheduler_data())
+        runq = erts_get_runq_current(NULL);
+    else
+        runq = ERTS_RUNQ_IX(0);
+    erts_smp_atomic_set_nob(&prt->run_queue, (erts_aint_t) runq);
+
     prt->xports = NULL;
 #else
     erts_atomic32_init_nob(&prt->refc, 1);
@@ -1535,6 +1544,26 @@ erts_schedule_proc2port_signal(Process *c_p,
     return ERTS_PORT_OP_SCHEDULED;
 }
 
+static int
+erts_schedule_port2port_signal(Eterm port_num, ErtsProc2PortSigData *sigdp,
+                               int task_flags,
+                               ErtsProc2PortSigCallback callback)
+{
+    Port *prt = erts_port_lookup_raw(port_num);
+
+    if (!prt)
+        return -1;
+
+    sigdp->caller = ERTS_INVALID_PID;
+
+    return erts_port_task_schedule(prt->common.id,
+                                   NULL,
+                                   ERTS_PORT_TASK_PROC_SIG,
+                                   sigdp,
+                                   callback,
+                                   task_flags);
+}
+
 static ERTS_INLINE void
 send_badsig(Port *prt) {
     ErtsProcLocks rp_locks = ERTS_PROC_LOCKS_XSIG_SEND;
@@ -2862,6 +2891,7 @@ void erts_init_io(int port_tab_size,
     init_driver(&fd_driver, &fd_driver_entry, NULL);
     init_driver(&vanilla_driver, &vanilla_driver_entry, NULL);
     init_driver(&spawn_driver, &spawn_driver_entry, NULL);
+    init_driver(&forker_driver, &forker_driver_entry, NULL);
     erts_init_static_drivers();
     for (dp = driver_tab; *dp != NULL; dp++)
 	erts_add_driver_entry(*dp, NULL, 1);
@@ -2923,6 +2953,7 @@ void erts_lcnt_enable_io_lock_count(int enable) {
 
     lcnt_enable_drv_lock_count(&vanilla_driver, enable);
     lcnt_enable_drv_lock_count(&spawn_driver, enable);
+    lcnt_enable_drv_lock_count(&forker_driver, enable);
     lcnt_enable_drv_lock_count(&fd_driver, enable);
     /* enable lock counting in all drivers */
     for (dp = driver_list; dp; dp = dp->next) {
@@ -3964,7 +3995,7 @@ port_sig_control(Port *prt,
 	    Uint hsz, rsz;
 	    int control_flags;
 
-	    rp = erts_proc_lookup_raw(sigdp->caller);
+	    rp = sigdp->caller == ERTS_INVALID_PID ? NULL : erts_proc_lookup_raw(sigdp->caller);
 	    if (!rp)
 		goto done;
 
@@ -4007,7 +4038,8 @@ port_sig_control(Port *prt,
 
     /* failure */
 
-    port_sched_op_reply(sigdp->caller, sigdp->ref, am_badarg);
+    if (sigdp->caller != ERTS_INVALID_PID)
+        port_sched_op_reply(sigdp->caller, sigdp->ref, am_badarg);
 
 done:
 
@@ -4017,6 +4049,23 @@ done:
     return ERTS_PORT_REDS_CONTROL;
 }
 
+/*
+ * This is an asynchronous control call. I.e. it will not return anything
+ * to the caller.
+ */
+int
+erl_drv_port_control(Eterm port_num, char cmd, char* buff, ErlDrvSizeT size)
+{
+    ErtsProc2PortSigData *sigdp = erts_port_task_alloc_p2p_sig_data();
+
+    sigdp->flags = ERTS_P2P_SIG_TYPE_CONTROL | ERTS_P2P_SIG_DATA_FLG_REPLY;
+    sigdp->u.control.binp = NULL;
+    sigdp->u.control.command = cmd;
+    sigdp->u.control.bufp = buff;
+    sigdp->u.control.size = size;
+
+    return erts_schedule_port2port_signal(port_num, sigdp, 0, port_sig_control);
+}
 
 ErtsPortOpResult
 erts_port_control(Process* c_p,
@@ -4794,6 +4843,8 @@ print_port_info(Port *p, int to, void *arg)
 	erts_print(to, arg, "Port is a file: %s\n",p->name);
     } else if (p->drv_ptr == &spawn_driver) {
 	erts_print(to, arg, "Port controls external process: %s\n",p->name);
+    } else if (p->drv_ptr == &forker_driver) {
+	erts_print(to, arg, "Port controls forker process: %s\n",p->name);
     } else {
 	erts_print(to, arg, "Port controls linked-in driver: %s\n",p->name);
     }
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index 34011147d9..522d899c94 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -61,15 +61,6 @@
 #  define NO_FPE_SIGNALS
 #endif
 
-#ifdef DISABLE_CHILD_WAITER_THREAD
-#undef ENABLE_CHILD_WAITER_THREAD
-#endif
-
-#if defined(ERTS_SMP) && !defined(DISABLE_CHILD_WAITER_THREAD)
-#undef ENABLE_CHILD_WAITER_THREAD
-#define ENABLE_CHILD_WAITER_THREAD 1
-#endif
-
 #define ERTS_I64_LITERAL(X) X##LL
 
 #if defined (__WIN32__)
@@ -731,6 +722,7 @@ void erts_sys_main_thread(void);
 extern int erts_sys_prepare_crash_dump(int secs);
 extern void erts_sys_pre_init(void);
 extern void erl_sys_init(void);
+extern void erl_sys_late_init(void);
 extern void erl_sys_args(int *argc, char **argv);
 extern void erl_sys_schedule(int);
 void sys_tty_reset(int);