From 676ab7c15ccb99e4e18cb1aceef60795223ab569 Mon Sep 17 00:00:00 2001 From: Kyotaro Horiguchi Date: Tue, 27 Sep 2016 16:21:54 +0900 Subject: [PATCH 2/3] hs-checkpoints-v12-2 Make XLOG_SWITCH NO_PROGRESS and manage log switching LSN to avoid excessive log switching and checkpoints. --- src/backend/access/transam/xlog.c | 2 ++ src/backend/postmaster/checkpointer.c | 40 +++++++++++++++++++++++++---------- 2 files changed, 31 insertions(+), 11 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 289d240..a582759 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -9191,6 +9191,8 @@ RequestXLogSwitch(void) /* XLOG SWITCH has no data */ XLogBeginInsert(); + + XLogSetFlags(XLOG_NO_PROGRESS); RecPtr = XLogInsert(RM_XLOG_ID, XLOG_SWITCH); return RecPtr; diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c index a729a3d..4b7ff4b 100644 --- a/src/backend/postmaster/checkpointer.c +++ b/src/backend/postmaster/checkpointer.c @@ -600,20 +600,38 @@ CheckArchiveTimeout(void) /* Now we can do the real check */ if ((int) (now - last_xlog_switch_time) >= XLogArchiveTimeout) { - XLogRecPtr switchpoint; - - /* OK, it's time to switch */ - elog(LOG, "Request XLog Switch"); - switchpoint = RequestXLogSwitch(); + static XLogRecPtr last_xlog_switch_lsn = InvalidXLogRecPtr; /* - * If the returned pointer points exactly to a segment boundary, - * assume nothing happened. + * switch segment only when any substantial progress have made from + * the last segment switching by timeout. Segment switching by other + * reasons will cause last_xlog_switch_lsn stay behind but it doesn't + * matter since it just causes possible one excessive segment switch. */ - if ((switchpoint % XLogSegSize) != 0) - ereport(DEBUG1, - (errmsg("transaction log switch forced (archive_timeout=%d)", - XLogArchiveTimeout))); + if (GetProgressRecPtr() > last_xlog_switch_lsn) + { + XLogRecPtr switchpoint; + + /* OK, it's time to switch */ + elog(LOG, "Request XLog Switch"); + switchpoint = RequestXLogSwitch(); + + /* + * If the returned pointer points exactly to a segment boundary, + * assume nothing happened. + */ + if ((switchpoint % XLogSegSize) != 0) + ereport(DEBUG1, + (errmsg("transaction log switch forced (archive_timeout=%d)", + XLogArchiveTimeout))); + + /* + * This switchpoint is not the LSN for the next XLOG record but + * just after this log switch record. But either will do for + * comparing with GetProgressRecPtr(). + */ + last_xlog_switch_lsn = switchpoint; + } /* * Update state in any case, so we don't retry constantly when the -- 2.9.2