yuanboliu commented on PR #4198: URL: https://github.com/apache/hadoop/pull/4198#issuecomment-1103914165
@steveloughran Thanks for your comment. Let's say a user submit an app, 1. submit by client (2022-04-20:20:00) 2. generate delegation token(2022-04-20:20:01) 3. then the delegation token expired time is (2022-04-27:20:00) 4. RM get the submitting event, process it asynchronously. 5. RM may be busy or not, suppose that the app is handled after several minutes(2022-04-20:25:01) 6. without this patch, RM will renew the token when handling submitting event, then the expire time is (2022-04-27:25:01) 7. next time for renewing this token is 2022-04-27 08:13:00 = (2022-04-27:25:01) - (2022-04-27:25:01) / 10 The Step 6 is not very necesarry as the expire time does not vary a lot (only several minutes) . I'll go through the history to see why RM needs to renew token immediately. Renewing token will be a heavy opertion in a very busy cluster(in our case, there are nearly 40, 000 apps an hour), as it uses namesystem write lock. --> And we can't assume that every hosts clocks in perfect sync Renewing immediately is not very helpful in this case, so I think it's harmless to remove Step 6. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
