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, 6 deletions

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