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Fix GH-13193: Significant performance degradation in 'foreach' starting from PHP 8.2.13 (caused by garbage collection) #13265

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Merged
merged 2 commits into from
Jan 30, 2024
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Fix GH-13193: Significant performance degradation in 'foreach' starting from PHP 8.2.13 (caused by garbage collection) #13265

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e0bdde0
Fix GH-13193: Significant performance degradation in 'foreach' starti…
dstogov Jan 29, 2024
a7559de
Don't run zend_gc_remove_root_tmpvars() if GC is not active or GC buf…
dstogov Jan 29, 2024
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41 changes: 38 additions & 3 deletions Zend/zend_gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1465,14 +1465,19 @@ static int gc_remove_nested_data_from_buffer(zend_refcounted *ref, gc_root_buffe
}

static void zend_get_gc_buffer_release(void);
static void zend_gc_root_tmpvars(void);
static void zend_gc_check_root_tmpvars(void);
static void zend_gc_remove_root_tmpvars(void);

ZEND_API int zend_gc_collect_cycles(void)
{
int total_count = 0;
bool should_rerun_gc = 0;
bool did_rerun_gc = 0;

if (GC_G(num_roots) && GC_G(gc_active)) {
zend_gc_remove_root_tmpvars();
}

rerun_gc:
if (GC_G(num_roots)) {
int count;
Expand Down Expand Up @@ -1669,7 +1674,7 @@ ZEND_API int zend_gc_collect_cycles(void)

finish:
zend_get_gc_buffer_release();
zend_gc_root_tmpvars();
zend_gc_check_root_tmpvars();
return total_count;
}

Expand Down Expand Up @@ -1707,7 +1712,7 @@ static void zend_get_gc_buffer_release(void) {
* cycles. However, there are some rare exceptions where this is possible, in which case we rely
* on the producing code to root the value. If a GC run occurs between the rooting and consumption
* of the value, we would end up leaking it. To avoid this, root all live TMPVAR values here. */
static void zend_gc_root_tmpvars(void) {
static void zend_gc_check_root_tmpvars(void) {
zend_execute_data *ex = EG(current_execute_data);
for (; ex; ex = ex->prev_execute_data) {
zend_function *func = ex->func;
Expand Down Expand Up @@ -1737,6 +1742,36 @@ static void zend_gc_root_tmpvars(void) {
}
}

static void zend_gc_remove_root_tmpvars(void) {
zend_execute_data *ex = EG(current_execute_data);
for (; ex; ex = ex->prev_execute_data) {
zend_function *func = ex->func;
if (!func || !ZEND_USER_CODE(func->type)) {
continue;
}

uint32_t op_num = ex->opline - ex->func->op_array.opcodes;
for (uint32_t i = 0; i < func->op_array.last_live_range; i++) {
const zend_live_range *range = &func->op_array.live_range[i];
if (range->start > op_num) {
break;
}
if (range->end <= op_num) {
continue;
}

uint32_t kind = range->var & ZEND_LIVE_MASK;
if (kind == ZEND_LIVE_TMPVAR || kind == ZEND_LIVE_LOOP) {
uint32_t var_num = range->var & ~ZEND_LIVE_MASK;
zval *var = ZEND_CALL_VAR(ex, var_num);
if (Z_REFCOUNTED_P(var)) {
GC_REMOVE_FROM_BUFFER(Z_COUNTED_P(var));
}
}
}
}
}

#ifdef ZTS
size_t zend_gc_globals_size(void)
{
Expand Down