From caad36a5e2fc09d6a416fe31a7053bdfdb35c62d Mon Sep 17 00:00:00 2001 From: Richard Carlsson Date: Sat, 13 Aug 2011 21:28:16 +0200 Subject: fix 64-bit issues in the garbage collection We discovered that if a single Erlang process tried to grow above 32 GB (i.e., more 64-bit words than can be counted by a 32-bit number), the VM failed to find the next larger heap size, even though there were plenty more heap sizes left to pick from and even though we had a lot more memory available on the machine. (Obviously, this is only applicable on 64-bit Erlang.) It turned out to be due to some 'int' variables in the heap resizing parts of erl_gc.c not being properly updated to 'Uint' or 'Sint'. Once that was fixed, I got segfaults instead as soon as the heap got larger than 2^32 words, due to even more 'int' declarations in the same file, but now in the GC code. After fixing this as well, I successfully ran an Erlang node in which a single Erlang process had a heap so large that I'm not at liberty to divulge the exact size, but I think the scientific term is "humongous", and I'm confident that there are no further immediate problems with very very large individual process heaps. --- erts/emulator/beam/erl_gc.c | 40 ++++++++++++++++++++++++---------------- 1 file changed, 24 insertions(+), 16 deletions(-) (limited to 'erts/emulator/beam/erl_gc.c') diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c index 5edcd667e7..e3445bcdc5 100644 --- a/erts/emulator/beam/erl_gc.c +++ b/erts/emulator/beam/erl_gc.c @@ -100,14 +100,14 @@ static Uint combined_message_size(Process* p); static void remove_message_buffers(Process* p); static int major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl); static int minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl); -static void do_minor(Process *p, int new_sz, Eterm* objv, int nobj); +static void do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj); static Eterm* sweep_rootset(Rootset *rootset, Eterm* htop, char* src, Uint src_size); static Eterm* sweep_one_area(Eterm* n_hp, Eterm* n_htop, char* src, Uint src_size); static Eterm* sweep_one_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop, char* src, Uint src_size); static Eterm* collect_heap_frags(Process* p, Eterm* heap, Eterm* htop, Eterm* objv, int nobj); -static Uint adjust_after_fullsweep(Process *p, int size_before, +static Uint adjust_after_fullsweep(Process *p, Uint size_before, int need, Eterm *objv, int nobj); static void shrink_new_heap(Process *p, Uint new_sz, Eterm *objv, int nobj); static void grow_new_heap(Process *p, Uint new_sz, Eterm* objv, int nobj); @@ -441,7 +441,15 @@ erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj) p->last_old_htop = p->old_htop; #endif - return ((int) (HEAP_TOP(p) - HEAP_START(p)) / 10); + /* FIXME: This function should really return an Sint, i.e., a possibly + 64 bit wide signed integer, but that requires updating all the code + that calls it. For now, we just return INT_MAX if the result is too + large for an int. */ + { + Sint result = (HEAP_TOP(p) - HEAP_START(p)) / 10; + if (result >= INT_MAX) return INT_MAX; + else return (int) result; + } } /* @@ -599,7 +607,7 @@ erts_garbage_collect_literals(Process* p, Eterm* literals, Uint lit_size) char* area; Uint area_size; Eterm* old_htop; - int n; + Uint n; /* * Set GC state. @@ -731,7 +739,7 @@ minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl) * This improved Estone by more than 1200 estones on my computer * (Ultra Sparc 10). */ - size_t new_sz = erts_next_heap_size(HEAP_TOP(p) - HEAP_START(p), 1); + Uint new_sz = erts_next_heap_size(HEAP_TOP(p) - HEAP_START(p), 1); /* Create new, empty old_heap */ n_old = (Eterm *) ERTS_HEAP_ALLOC(ERTS_ALC_T_OLD_HEAP, @@ -871,12 +879,12 @@ minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl) #endif /* HIPE */ static void -do_minor(Process *p, int new_sz, Eterm* objv, int nobj) +do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj) { Rootset rootset; /* Rootset for GC (stack, dictionary, etc). */ Roots* roots; Eterm* n_htop; - int n; + Uint n; Eterm* ptr; Eterm val; Eterm gval; @@ -1079,14 +1087,14 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl) { Rootset rootset; Roots* roots; - int size_before; + Uint size_before; Eterm* n_heap; Eterm* n_htop; char* src = (char *) HEAP_START(p); Uint src_size = (char *) HEAP_TOP(p) - src; char* oh = (char *) OLD_HEAP(p); Uint oh_size = (char *) OLD_HTOP(p) - oh; - int n; + Uint n; Uint new_sz; Uint fragments = MBUF_SIZE(p) + combined_message_size(p); ErlMessage *msgp; @@ -1312,10 +1320,10 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl) } static Uint -adjust_after_fullsweep(Process *p, int size_before, int need, Eterm *objv, int nobj) +adjust_after_fullsweep(Process *p, Uint size_before, int need, Eterm *objv, int nobj) { - int wanted, sz, size_after, need_after; - int stack_size = STACK_SZ_ON_HEAP(p); + Uint wanted, sz, size_after, need_after; + Uint stack_size = STACK_SZ_ON_HEAP(p); Uint reclaimed_now; size_after = (HEAP_TOP(p) - HEAP_START(p)); @@ -1915,8 +1923,8 @@ static void grow_new_heap(Process *p, Uint new_sz, Eterm* objv, int nobj) { Eterm* new_heap; - int heap_size = HEAP_TOP(p) - HEAP_START(p); - int stack_size = p->hend - p->stop; + Uint heap_size = HEAP_TOP(p) - HEAP_START(p); + Uint stack_size = p->hend - p->stop; Sint offs; ASSERT(HEAP_SIZE(p) < new_sz); @@ -1954,10 +1962,10 @@ static void shrink_new_heap(Process *p, Uint new_sz, Eterm *objv, int nobj) { Eterm* new_heap; - int heap_size = HEAP_TOP(p) - HEAP_START(p); + Uint heap_size = HEAP_TOP(p) - HEAP_START(p); Sint offs; - int stack_size = p->hend - p->stop; + Uint stack_size = p->hend - p->stop; ASSERT(new_sz < p->heap_sz); sys_memmove(p->heap + new_sz - stack_size, p->stop, stack_size * -- cgit v1.2.3