Changeset 60925

Timestamp:

10/12/2025 09:40:08 PM (7 months ago)

Author:

peterwilsoncc

Message:

Cron API: Spawn cron jobs on shutdown hook.

Modifies wp_cron() to register the spawning of cron jobs on the shutdown hook rather than the wp_loaded hook.

The loopback request made while spawning cron jobs is intended to be non-blocking, however in some circumstances that isn't the case and the spawning will increase the time to first byte.

Props westonruter, pmbaldha, mukesh27.
Fixes #63858.

Location:

trunk

Files:

• src/wp-includes/cron.php (modified) (1 diff)
• tests/phpunit/tests/cron.php (modified) (1 diff)

trunk/src/wp-includes/cron.php

@@ -973 +973 @@
 
 /**
- * Registers _wp_cron() to run on the {@see 'wp_loaded'} action.
- *
- * If the {@see 'wp_loaded'} action has already fired, this function calls
- * _wp_cron() directly.
- *
- * Warning: This function may return Boolean FALSE, but may also return a non-Boolean
- * value which evaluates to FALSE. For information about casting to booleans see the
- * {@link https://www.php.net/manual/en/language.types.boolean.php PHP documentation}. Use
- * the `===` operator for testing the return value of this function.
+ * Registers _wp_cron() to run on the {@see 'shutdown'} action.
+ *
+ * The spawn_cron() function attempts to make a non-blocking loopback request to `wp-cron.php` (when alternative
+ * cron is not being used). However, the wp_remote_post() function does not always respect the `timeout` and
+ * `blocking` parameters. A timeout of `0.01` may end up taking 1 second. When this runs at the {@see 'wp_loaded'}
+ * action, it increases the Time To First Byte (TTFB) since the HTML cannot be sent while waiting for the cron request
+ * to initiate. Moving the spawning of cron to the {@see 'shutdown'} hook allows for the server to flush the HTML document to
+ * the browser while waiting for the request.
  *
  * @since 2.1.0
  * @since 5.1.0 Return value added to indicate success or failure.
  * @since 5.7.0 Functionality moved to _wp_cron() to which this becomes a wrapper.
- *
- * @return false|int|void On success an integer indicating number of events spawned (0 indicates no
- *                        events needed to be spawned), false if spawning fails for one or more events or
- *                        void if the function registered _wp_cron() to run on the action.
- */
-function wp_cron() {
-    if ( did_action( 'wp_loaded' ) ) {
-        return _wp_cron();
-    }
-
-    add_action( 'wp_loaded', '_wp_cron', 20 );
+ * @since 6.9.0 The _wp_cron() callback is moved from {@see 'wp_loaded'} to the {@see 'shutdown'} action; the function always returns void.
+ */
+function wp_cron(): void {
+    if ( doing_action( 'shutdown' ) ) {
+        _wp_cron();
+    } else {
+        add_action( 'shutdown', '_wp_cron' );
+    }
 }
 

trunk/tests/phpunit/tests/cron.php

@@ -1331 +1331 @@
         $this->assertSame( 'could_not_set', $unscheduled->get_error_code() );
     }
+
+    /**
+     * @ticket 63858
+     *
+     * @covers ::wp_cron
+     */
+    public function test_wp_cron_before_shutdown() {
+        remove_all_actions( 'shutdown' );
+        wp_cron();
+        $this->assertSame( 10, has_action( 'shutdown', '_wp_cron' ), 'Expected _wp_cron() to be scheduled for shutdown.' );
+    }
+
+    /**
+     * @ticket 63858
+     *
+     * @covers ::wp_cron
+     */
+    public function test_wp_cron_already_at_shutdown() {
+        remove_all_actions( 'shutdown' );
+        add_action( 'shutdown', 'wp_cron' );
+        do_action( 'shutdown' );
+        $this->assertFalse( has_action( 'shutdown', '_wp_cron' ), 'Expected wp_cron() to not add _wp_cron() to run at shutdown.' );
+    }
 }