Is the browser multi process or single process?

Browsers are multi-process , every last tab Page represents a process , If more than one is empty tab Pages join into a process （webkit））

There are many threads under each process , Let's introduce in detail ：

• GUI Rendering thread

The main work of the rendering engine is to HTML The structure is DOM Trees , take CSS The structure is CSSOM Trees ,DOM Trees and CSSOM The trees merge into render Trees , Render as layout , Finally, it is drawn as a browser page .

The interface needs to be redrawn （Repaint） Or cause reflux due to an operation ( Reflow ) when , The thread will execute .

• JS Engine threads

JS The engine thread is responsible for parsing and executing javascript Script

JS Engine threads and GUI Rendering thread They are mutually exclusive. If JS The engine takes too long , Will block the rendering engine , As a result, the page rendering speed is very slow

• Event trigger thread

JS The engine is executing javascript Code , The corresponding execution stack will be formed , Perform synchronization tasks , The event callback of asynchronous task is thrown to the task queue . Wait for the synchronization task to complete , Perform tasks in the task queue （ Macro task , Micro task ）

• Timer trigger thread

When the timer is turned on , Trigger timer thread , After the timer ends , The event callback function is added to the task queue , wait for JS Engine processing

• http Request thread

When http A request thread will be opened when requesting
When the request is completed , Add the requested callback function to the task queue , wait for JS Engine processing