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Fix finalizer resuscitation causing excessive GC

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* libguile/finalizers.c (async_gc_finalizer):
  (scm_i_register_async_gc_callback): Replace "weak gc callback"
  mechanism with "async gc callback" mechanism.  Very similar but the
  new API is designed to be called a bounded number of times, to avoid
  running afoul of libgc heuristics.
* libguile/weak-list.h: New internal header.
* libguile/Makefile.am (noinst_HEADERS): Add weak-list.h.
* libguile/weak-set.c (vacuum_all_weak_sets):
  (scm_c_make_weak_set, scm_init_weak_set):
* libguile/weak-table.c (vacuum_all_weak_tables):
  (scm_c_make_weak_table, scm_init_weak_table): Arrange to vacuum all
  weak sets from a single async GC callback, and likewise for weak
  tables.

Thanks to Ludovic Courtès for tracking this bug down!
This commit is contained in:
Andy Wingo 2017-03-13 15:47:51 +01:00
parent e337432041
commit c9910c6042
6 changed files with 137 additions and 43 deletions
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18
libguile/weak-table.c
View file

@ -33,6 +33,7 @@
#include "libguile/ports.h"
#include "libguile/validate.h"
#include "libguile/weak-list.h"
#include "libguile/weak-table.h"
@ -832,6 +833,17 @@ do_vacuum_weak_table (SCM table)
return;
}
static scm_i_pthread_mutex_t all_weak_tables_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER;
static SCM all_weak_tables = SCM_EOL;
static void
vacuum_all_weak_tables (void)
{
scm_i_pthread_mutex_lock (&all_weak_tables_lock);
scm_i_visit_weak_list (&all_weak_tables, do_vacuum_weak_table);
scm_i_pthread_mutex_unlock (&all_weak_tables_lock);
}
SCM
scm_c_make_weak_table (unsigned long k, scm_t_weak_table_kind kind)
{
@ -839,7 +851,9 @@ scm_c_make_weak_table (unsigned long k, scm_t_weak_table_kind kind)
ret = make_weak_table (k, kind);
scm_i_register_weak_gc_callback (ret, do_vacuum_weak_table);
scm_i_pthread_mutex_lock (&all_weak_tables_lock);
all_weak_tables = scm_i_weak_cons (ret, all_weak_tables);
scm_i_pthread_mutex_unlock (&all_weak_tables_lock);
return ret;
}
@ -1155,6 +1169,8 @@ void
scm_init_weak_table ()
{
#include "libguile/weak-table.x"
scm_i_register_async_gc_callback (vacuum_all_weak_tables);
}
/*