blocking of thread occurs

Flow
1

When simultaneous refreshing occurs in Table data,
when synchronous scrolling of table and updating data from server , threads are block and CPU usage increase to 100 % and server hangs.

2

Hi! Cannot say much based on this, but afaik the HTTP request-response cycle locks the application instance to render the changes, but that should not cause any dramatic side affects. Make sure you read this one:
vaadin.com/forum/-/message_boards/view_message/231271

3

To really highlight the usual cause for such problems: if you’re updating the contents from outside the request/response cycle (i.e from a separate thread), you must synchronize on the application instance while updating.

 synchronized (application) { ... }

Best Regards,
Marc