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backport memory pressure callback to 1.9 (#114)
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d-netto authored and Drvi committed Feb 28, 2024
1 parent 4aa96c0 commit bb92c7e
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Showing 2 changed files with 17 additions and 10 deletions.
23 changes: 13 additions & 10 deletions src/gc.c
Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,6 @@ static jl_gc_callback_list_t *gc_cblist_post_gc;
static jl_gc_callback_list_t *gc_cblist_notify_external_alloc;
static jl_gc_callback_list_t *gc_cblist_notify_external_free;
static jl_gc_callback_list_t *gc_cblist_notify_gc_pressure;
typedef void (*jl_gc_cb_notify_gc_pressure_t)(void);

#define gc_invoke_callbacks(ty, list, args) \
do { \
Expand Down Expand Up @@ -138,12 +137,12 @@ JL_DLLEXPORT void jl_gc_set_cb_notify_external_free(jl_gc_cb_notify_external_fre
}

JL_DLLEXPORT void jl_gc_set_cb_notify_gc_pressure(jl_gc_cb_notify_gc_pressure_t cb, int enable)
{
if (enable)
jl_gc_register_callback(&gc_cblist_notify_gc_pressure, (jl_gc_cb_func_t)cb);
else
jl_gc_deregister_callback(&gc_cblist_notify_gc_pressure, (jl_gc_cb_func_t)cb);
}
{
if (enable)
jl_gc_register_callback(&gc_cblist_notify_gc_pressure, (jl_gc_cb_func_t)cb);
else
jl_gc_deregister_callback(&gc_cblist_notify_gc_pressure, (jl_gc_cb_func_t)cb);
}

// Protect all access to `finalizer_list_marked` and `to_finalize`.
// For accessing `ptls->finalizers`, the lock is needed if a thread
Expand Down Expand Up @@ -676,6 +675,7 @@ static void gc_sweep_foreign_objs(void)
}

// GC knobs and self-measurement variables
static int under_memory_pressure;
static int64_t last_gc_total_bytes = 0;

// max_total_memory is a suggestion. We try very hard to stay
Expand Down Expand Up @@ -2958,7 +2958,7 @@ size_t gc_count_work_in_queue(jl_ptls_t ptls) JL_NOTSAFEPOINT
* have tried to steal from the queue which still has a work item left, but failed to do so,
* which violates the semantics of Chase-Lev's work-stealing queue.
*
* - Let E1 be the event "master thread writes -1 to gc_master_tid" and E2 be the even
* - Let E1 be the event "master thread writes -1 to gc_master_tid" and E2 be the event
* "master thread observes that `gc_n_threads_marking` is zero". Since we're using
* sequentially consistent atomics, E1 => E2. Now suppose one thread which is spinning in
* `gc_should_mark` tries to enter the mark-loop after E2. In order to do so, it must
Expand Down Expand Up @@ -3502,6 +3502,7 @@ static int _jl_gc_collect(jl_ptls_t ptls, jl_gc_collection_t collection)
// If the live data outgrows the suggested max_total_memory
// we keep going with full gcs until we either free some space or get an OOM error.
if (live_bytes > max_total_memory) {
under_memory_pressure = 1;
sweep_full = 1;
}
if (gc_sweep_always_full) {
Expand Down Expand Up @@ -3709,10 +3710,12 @@ JL_DLLEXPORT void jl_gc_collect(jl_gc_collection_t collection)

gc_invoke_callbacks(jl_gc_cb_post_gc_t,
gc_cblist_post_gc, (collection));
if (under_pressure)

if (under_memory_pressure) {
gc_invoke_callbacks(jl_gc_cb_notify_gc_pressure_t,
gc_cblist_notify_gc_pressure, ());
under_pressure = 0;
}
under_memory_pressure = 0;
#ifdef _OS_WINDOWS_
SetLastError(last_error);
#endif
Expand Down
4 changes: 4 additions & 0 deletions src/julia_gcext.h
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,10 @@ JL_DLLEXPORT void jl_gc_set_cb_notify_external_alloc(jl_gc_cb_notify_external_al
JL_DLLEXPORT void jl_gc_set_cb_notify_external_free(jl_gc_cb_notify_external_free_t cb,
int enable);

// Memory pressure callback
typedef void (*jl_gc_cb_notify_gc_pressure_t)(void);
JL_DLLEXPORT void jl_gc_set_cb_notify_gc_pressure(jl_gc_cb_notify_gc_pressure_t cb, int enable);

// Types for custom mark and sweep functions.
typedef uintptr_t (*jl_markfunc_t)(jl_ptls_t, jl_value_t *obj);
typedef void (*jl_sweepfunc_t)(jl_value_t *obj);
Expand Down

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