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

1 files changed, 0 insertions, 37 deletions

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);