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Add v8js.thread_pool_size INI directive to control V8 thread pool size #548

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Add v8js.thread_pool_size INI directive to control V8 thread pool size #548

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826660e
Add `v8js.thread_pool_size` INI directive to control V8 thread pool size
Appla Sep 15, 2026
ef89fae
test: add PHPT test coverage for v8js.thread_pool_size directive
Appla Sep 16, 2026
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3 changes: 3 additions & 0 deletions php_v8js_macros.h
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,9 @@ struct _v8js_process_globals {
/* Path to icudtl.dat file */
char *icudtl_dat_path;

/* Number of V8 platform background worker threads */
int thread_pool_size;

std::unique_ptr<v8::Platform> v8_platform;
};

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76 changes: 76 additions & 0 deletions tests/thread_pool_size.phpt
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@@ -0,0 +1,76 @@
--TEST--
v8js.thread_pool_size INI directive validation and lifecycle
--SKIPIF--
<?php require_once(dirname(__FILE__) . '/skipif.inc'); ?>
--INI--
v8js.thread_pool_size=0
--FILE--
<?php
// 1. Initial value
var_dump(ini_get('v8js.thread_pool_size'));

// 2. Valid values before initialization (including boundaries 0 and 64)
var_dump(ini_set('v8js.thread_pool_size', '1'));
var_dump(ini_get('v8js.thread_pool_size'));

var_dump(ini_set('v8js.thread_pool_size', '64'));
var_dump(ini_get('v8js.thread_pool_size'));

var_dump(ini_set('v8js.thread_pool_size', '0'));
var_dump(ini_get('v8js.thread_pool_size'));

var_dump(ini_set('v8js.thread_pool_size', '4'));
var_dump(ini_get('v8js.thread_pool_size'));

// 3. Out-of-range and malformed values (must return false, value remains unchanged)
var_dump(ini_set('v8js.thread_pool_size', '-1'));
var_dump(ini_set('v8js.thread_pool_size', '-42'));
var_dump(ini_set('v8js.thread_pool_size', '65'));
var_dump(ini_set('v8js.thread_pool_size', '100'));
var_dump(@ini_set('v8js.thread_pool_size', '-1foo'));
var_dump(@ini_set('v8js.thread_pool_size', '100M'));
var_dump(ini_get('v8js.thread_pool_size'));

// 4. Initialize V8 platform by creating an instance
$v8 = new V8Js();
var_dump($v8->executeString('1 + 2'));

// 5. Attempts to change setting after initialization must fail
var_dump(ini_set('v8js.thread_pool_size', '2'));
var_dump(ini_set('v8js.thread_pool_size', '0'));
var_dump(ini_set('v8js.thread_pool_size', '64'));
var_dump(ini_get('v8js.thread_pool_size'));

// 6. Attempts to change setting after destroying instance must still fail
unset($v8);
var_dump(ini_set('v8js.thread_pool_size', '8'));
var_dump(ini_set('v8js.thread_pool_size', '0'));
var_dump(ini_get('v8js.thread_pool_size'));
?>
===EOF===
--EXPECT--
string(1) "0"
string(1) "0"
string(1) "1"
string(1) "1"
string(2) "64"
string(2) "64"
string(1) "0"
string(1) "0"
string(1) "4"
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
string(1) "4"
int(3)
bool(false)
bool(false)
bool(false)
string(1) "4"
bool(false)
bool(false)
string(1) "4"
===EOF===
30 changes: 30 additions & 0 deletions v8js_main.cc
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Expand Up @@ -112,11 +112,41 @@ static ZEND_INI_MH(v8js_OnUpdateUseArrayAccess) /* {{{ */
}
/* }}} */

static ZEND_INI_MH(v8js_OnUpdateThreadPoolSize) /* {{{ */
{
#if PHP_VERSION_ID < 80200
zend_long tmp = zend_atol(ZSTR_VAL(new_value), ZSTR_LEN(new_value));
#else
zend_long tmp = zend_ini_parse_quantity_warn(new_value, entry->name);
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#endif
/* V8 has hard limit of 16 threads for now, we allow up to 64 */
if (tmp < 0 || tmp > 64) {
return FAILURE;
}

#ifdef ZTS
std::lock_guard<std::mutex> lock(v8js_process_globals.lock);
if (v8js_process_globals.v8_initialized) {
return FAILURE;
}
#else
/* V8 already has been initialized -> cannot be changed anymore */
if (V8JSG(v8_initialized)) {
return FAILURE;
}
#endif

v8js_process_globals.thread_pool_size = static_cast<int>(tmp);
return SUCCESS;
}
/* }}} */

ZEND_INI_BEGIN() /* {{{ */
ZEND_INI_ENTRY("v8js.flags", NULL, ZEND_INI_ALL, v8js_OnUpdateV8Flags)
ZEND_INI_ENTRY("v8js.icudtl_dat_path", NULL, ZEND_INI_ALL, v8js_OnUpdateIcudatPath)
ZEND_INI_ENTRY("v8js.use_date", "0", ZEND_INI_ALL, v8js_OnUpdateUseDate)
ZEND_INI_ENTRY("v8js.use_array_access", "0", ZEND_INI_ALL, v8js_OnUpdateUseArrayAccess)
ZEND_INI_ENTRY("v8js.thread_pool_size", "0", ZEND_INI_ALL, v8js_OnUpdateThreadPoolSize)
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ZEND_INI_END()
/* }}} */

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6 changes: 5 additions & 1 deletion v8js_v8.cc
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Expand Up @@ -68,7 +68,11 @@ void v8js_v8_init() /* {{{ */
#endif
#endif

v8js_process_globals.v8_platform = v8::platform::NewDefaultPlatform();
if (v8js_process_globals.thread_pool_size > 0) {
v8js_process_globals.v8_platform = v8::platform::NewDefaultPlatform(v8js_process_globals.thread_pool_size);
} else {
v8js_process_globals.v8_platform = v8::platform::NewDefaultPlatform();
}
v8::V8::InitializePlatform(v8js_process_globals.v8_platform.get());

#ifdef V8_HAS_INITIALIZE_SANDBOX
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