The problem happens when one of the processes (parent or child) tries to modify a page. Modifying the page triggers the copy-on-write mechanism and blocks the process making the modifications - it doesn't matter if it's parent or child. In Redis' case, the BGSAVE process doesn't do any writes - so it's good. It's always the server process that does the writes.
Comments
The problem happens when one of the processes (parent or child) tries to modify a page. Modifying the page triggers the copy-on-write mechanism and blocks the process making the modifications - it doesn't matter if it's parent or child. In Redis' case, the BGSAVE process doesn't do any writes - so it's good. It's always the server process that does the writes.