From 10238fad0389175f71739bc9b4d00bb24d9b8c44 Mon Sep 17 00:00:00 2001 From: Magnus Hagander Date: Mon, 19 Dec 2016 10:11:04 +0100 Subject: [PATCH] Fix base backup rate limiting in presence of slow i/o When source i/o on disk was too slow compared to the rate limiting specified, the system could end up with a negative value for sleep that it never got out of, which caused rate limiting to effectively be turned off. Discussion: https://postgr.es/m/CABUevEy_-e0YvL4ayoX8bH_Ja9w%2BBHoP6jUgdxZuG2nEj3uAfQ%40mail.gmail.com Analysis by me, patch by Antonin Houska --- src/backend/replication/basebackup.c | 24 +++++++----------------- 1 file changed, 7 insertions(+), 17 deletions(-) diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c index ffc7e586db..40b3c117e8 100644 --- a/src/backend/replication/basebackup.c +++ b/src/backend/replication/basebackup.c @@ -1370,26 +1370,16 @@ throttle(size_t increment) if (wait_result & WL_LATCH_SET) CHECK_FOR_INTERRUPTS(); } - else - { - /* - * The actual transfer rate is below the limit. A negative value - * would distort the adjustment of throttled_last. - */ - wait_result = 0; - sleep = 0; - } /* - * Only a whole multiple of throttling_sample was processed. The rest will - * be done during the next call of this function. + * As we work with integers, only whole multiple of throttling_sample was + * processed. The rest will be done during the next call of this function. */ throttling_counter %= throttling_sample; - /* Once the (possible) sleep has ended, new period starts. */ - if (wait_result & WL_TIMEOUT) - throttled_last += elapsed + sleep; - else if (sleep > 0) - /* Sleep was necessary but might have been interrupted. */ - throttled_last = GetCurrentIntegerTimestamp(); + /* + * Time interval for the remaining amount and possible next increments + * starts now. + */ + throttled_last = GetCurrentIntegerTimestamp(); } -- 2.40.0