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Support for fine-grained selection of the GC collection type. #33448

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Oct 4, 2019
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Support for fine-grained selection of the GC collection type. #33448

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d378da8
Support for fine-grained selection of the GC collection type.
maleadt Oct 2, 2019
c3d4a32
Add a Julia interface.
maleadt Oct 3, 2019
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20 changes: 17 additions & 3 deletions base/gcutils.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -49,15 +49,29 @@ Module with garbage collection utilities.
"""
module GC

# @enum-like structure
struct CollectionType
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@KristofferC KristofferC Oct 3, 2019

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Out of curiosity, what is the reason for not using an actual @enum?

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@maleadt maleadt Oct 3, 2019

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gcutils.jl is included very early in the system image, before Enums.jl and having @enum.

x::Int
end
Base.cconvert(::Type{Cint}, collection::CollectionType) = Cint(collection.x)

const Auto = CollectionType(0)
const Full = CollectionType(1)
const Incremental = CollectionType(2)

"""
GC.gc()
GC.gc(full::Bool=true)
GC.gc(collection::CollectionType)

Perform garbage collection.
Perform garbage collection. The argument `full` determines whether a full, but more costly
collection is performed. Otherwise, heuristics are used to determine which type of
collection is needed. For exact control, pass an argument of type `CollectionType`.

!!! warning
Excessive use will likely lead to poor performance.
"""
gc(full::Bool=true) = ccall(:jl_gc_collect, Cvoid, (Int32,), full)
gc(full::Bool=true) = ccall(:jl_gc_collect, Cvoid, (Cint,), full)
gc(collection::CollectionType) = ccall(:jl_gc_collect, Cvoid, (Cint,), collection)

"""
GC.enable(on::Bool)
Expand Down
25 changes: 14 additions & 11 deletions src/gc.c
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Expand Up @@ -778,7 +778,7 @@ void jl_gc_force_mark_old(jl_ptls_t ptls, jl_value_t *v) JL_NOTSAFEPOINT
static inline void maybe_collect(jl_ptls_t ptls)
{
if (ptls->gc_num.allocd >= 0 || gc_debug_check_other()) {
jl_gc_collect(0);
jl_gc_collect(JL_GC_AUTO);
}
else {
jl_gc_safepoint_(ptls);
Expand Down Expand Up @@ -2667,7 +2667,7 @@ static void jl_gc_queue_bt_buf(jl_gc_mark_cache_t *gc_cache, jl_gc_mark_sp_t *sp
size_t jl_maxrss(void);

// Only one thread should be running in this function
static int _jl_gc_collect(jl_ptls_t ptls, int full)
static int _jl_gc_collect(jl_ptls_t ptls, jl_gc_collection_t collection)
{
combine_thread_gc_counts(&gc_num);

Expand Down Expand Up @@ -2697,7 +2697,7 @@ static int _jl_gc_collect(jl_ptls_t ptls, int full)
if (gc_cblist_root_scanner) {
export_gc_state(ptls, &sp);
gc_invoke_callbacks(jl_gc_cb_root_scanner_t,
gc_cblist_root_scanner, (full));
gc_cblist_root_scanner, (collection));
import_gc_state(ptls, &sp);
}
gc_mark_loop(ptls, sp);
Expand Down Expand Up @@ -2775,12 +2775,14 @@ static int _jl_gc_collect(jl_ptls_t ptls, int full)
else if (live_bytes >= last_live_bytes) {
grown_heap_age++;
}
if ((full || large_frontier ||
if (collection == JL_GC_INCREMENTAL) {
sweep_full = 0;
} else if ((collection == JL_GC_FULL || large_frontier ||
((not_freed_enough || promoted_bytes >= gc_num.interval) &&
(promoted_bytes >= default_collect_interval || prev_sweep_full)) ||
grown_heap_age > 1) &&
gc_num.pause > 1) {
recollect = full;
recollect = (collection == JL_GC_FULL);
if (large_frontier)
gc_num.interval = last_long_collect_interval;
if (not_freed_enough || large_frontier) {
Expand Down Expand Up @@ -2869,7 +2871,7 @@ static int _jl_gc_collect(jl_ptls_t ptls, int full)
return recollect;
}

JL_DLLEXPORT void jl_gc_collect(int full)
JL_DLLEXPORT void jl_gc_collect(jl_gc_collection_t collection)
{
jl_ptls_t ptls = jl_get_ptls_states();
if (jl_gc_disable_counter) {
Expand All @@ -2896,12 +2898,13 @@ JL_DLLEXPORT void jl_gc_collect(int full)
// no-op for non-threading
jl_gc_wait_for_the_world();
gc_invoke_callbacks(jl_gc_cb_pre_gc_t,
gc_cblist_pre_gc, (full));
gc_cblist_pre_gc, (collection));

if (!jl_gc_disable_counter) {
JL_LOCK_NOGC(&finalizers_lock);
if (_jl_gc_collect(ptls, full)) {
int ret = _jl_gc_collect(ptls, 0);
if (_jl_gc_collect(ptls, collection)) {
// recollect
int ret = _jl_gc_collect(ptls, JL_GC_AUTO);
(void)ret;
assert(!ret);
}
Expand All @@ -2922,7 +2925,7 @@ JL_DLLEXPORT void jl_gc_collect(int full)
ptls->in_finalizer = was_in_finalizer;
}
gc_invoke_callbacks(jl_gc_cb_post_gc_t,
gc_cblist_post_gc, (full));
gc_cblist_post_gc, (collection));
}

void gc_mark_queue_all_roots(jl_ptls_t ptls, jl_gc_mark_sp_t *sp)
Expand Down Expand Up @@ -3332,7 +3335,7 @@ JL_DLLEXPORT int jl_gc_enable_conservative_gc_support(void)
// properly. We don't have to worry about race conditions
// for this part, as allocation itself is unproblematic and
// a collection will wait for safepoints.
jl_gc_collect(1);
jl_gc_collect(JL_GC_FULL);
}
return result;
} else {
Expand Down
8 changes: 7 additions & 1 deletion src/julia.h
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Expand Up @@ -746,7 +746,13 @@ JL_DLLEXPORT int64_t jl_gc_total_bytes(void);
JL_DLLEXPORT uint64_t jl_gc_total_hrtime(void);
JL_DLLEXPORT int64_t jl_gc_diff_total_bytes(void);

JL_DLLEXPORT void jl_gc_collect(int);
typedef enum {
JL_GC_AUTO = 0, // use heuristics to determine the collection type
JL_GC_FULL = 1, // force a full collection
JL_GC_INCREMENTAL = 2, // force an incremental collection
} jl_gc_collection_t;

JL_DLLEXPORT void jl_gc_collect(jl_gc_collection_t);

JL_DLLEXPORT void jl_gc_add_finalizer(jl_value_t *v, jl_function_t *f);
JL_DLLEXPORT void jl_finalize(jl_value_t *o);
Expand Down
4 changes: 2 additions & 2 deletions src/staticdata.c
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Expand Up @@ -1269,8 +1269,8 @@ static void jl_cleanup_serializer2(void);

static void jl_save_system_image_to_stream(ios_t *f)
{
jl_gc_collect(1); // full
jl_gc_collect(0); // incremental (sweep finalizers)
jl_gc_collect(JL_GC_FULL);
jl_gc_collect(JL_GC_INCREMENTAL); // sweep finalizers
JL_TIMING(SYSIMG_DUMP);
int en = jl_gc_enable(0);
jl_init_serializer2(1);
Expand Down
9 changes: 9 additions & 0 deletions test/misc.jl
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Expand Up @@ -758,3 +758,12 @@ end
# Finalizer with immutable should throw
@test_throws ErrorException finalizer(x->nothing, 1)
@test_throws ErrorException finalizer(C_NULL, 1)


@testset "GC utilities" begin
GC.gc()
GC.gc(true); GC.gc(false)
GC.gc(GC.Auto); GC.gc(GC.Full); GC.gc(GC.Incremental)

GC.safepoint()
end