rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
postgresql/src/include/postmaster/bgwriter.h

Ignoring revisions in .git-blame-ignore-revs. Click here to bypass and see the normal blame view.

46 lines
1.3 KiB
C
Raw Normal View History

Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
/*-------------------------------------------------------------------------
*
* bgwriter.h
Improve control logic for bgwriter hibernation mode. Commit 6d90eaaa89a007e0d365f49d6436f35d2392cfeb added a hibernation mode to the bgwriter to reduce the server's idle-power consumption. However, its interaction with the detailed behavior of BgBufferSync's feedback control loop wasn't very well thought out. That control loop depends primarily on the rate of buffer allocation, not the rate of buffer dirtying, so the hibernation mode has to be designed to operate only when no new buffer allocations are happening. Also, the check for whether the system is effectively idle was not quite right and would fail to detect a constant low level of activity, thus allowing the bgwriter to go into hibernation mode in a way that would let the cycle time vary quite a bit, possibly further confusing the feedback loop. To fix, move the wakeup support from MarkBufferDirty and SetBufferCommitInfoNeedsSave into StrategyGetBuffer, and prevent the bgwriter from entering hibernation mode unless no buffer allocations have happened recently. In addition, fix the delaying logic to remove the problem of possibly not responding to signals promptly, which was basically caused by trying to use the process latch's is_set flag for multiple purposes. I can't prove it but I'm suspicious that that hack was responsible for the intermittent "postmaster does not shut down" failures we've been seeing in the buildfarm lately. In any case it did nothing to improve the readability or robustness of the code. In passing, express the hibernation sleep time as a multiplier on BgWriterDelay, not a constant. I'm not sure whether there's any value in exposing the longer sleep time as an independently configurable setting, but we can at least make it act like this for little extra code.
2012-05-10 05:36:01 +02:00
* Exports from postmaster/bgwriter.c and postmaster/checkpointer.c.
*
* The bgwriter process used to handle checkpointing duties too. Now
* there is a separate process, but we did not bother to split this header.
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
*
Update copyright for 2022 Backpatch-through: 10
2022-01-08 01:04:57 +01:00
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
*
Remove cvs keywords from all files.
2010-09-20 22:08:53 +02:00
* src/include/postmaster/bgwriter.h
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
*
*-------------------------------------------------------------------------
*/
#ifndef _BGWRITER_H
#define _BGWRITER_H
Per previous discussions, get rid of use of sync(2) in favor of explicitly fsync'ing every (non-temp) file we have written since the last checkpoint. In the vast majority of cases, the burden of the fsyncs should fall on the bgwriter process not on backends. (To this end, we assume that an fsync issued by the bgwriter will force out blocks written to the same file by other processes using other file descriptors. Anyone have a problem with that?) This makes the world safe for WIN32, which ain't even got sync(2), and really makes the world safe for Unixen as well, because sync(2) never had the semantics we need: it offers no way to wait for the requested I/O to finish. Along the way, fix a bug I recently introduced in xlog recovery: file truncation replay failed to clear bufmgr buffers for the dropped blocks, which could result in 'PANIC: heap_delete_redo: no block' later on in xlog replay.
2004-05-31 05:48:10 +02:00
#include "storage/block.h"
Change internal RelFileNode references to RelFileNumber or RelFileLocator. We have been using the term RelFileNode to refer to either (1) the integer that is used to name the sequence of files for a certain relation within the directory set aside for that tablespace/database combination; or (2) that value plus the OIDs of the tablespace and database; or occasionally (3) the whole series of files created for a relation based on those values. Using the same name for more than one thing is confusing. Replace RelFileNode with RelFileNumber when we're talking about just the single number, i.e. (1) from above, and with RelFileLocator when we're talking about all the things that are needed to locate a relation's files on disk, i.e. (2) from above. In the places where we refer to (3) as a relfilenode, instead refer to "relation storage". Since there is a ton of SQL code in the world that knows about pg_class.relfilenode, don't change the name of that column, or of other SQL-facing things that derive their name from it. On the other hand, do adjust closely-related internal terminology. For example, the structure member names dbNode and spcNode appear to be derived from the fact that the structure itself was called RelFileNode, so change those to dbOid and spcOid. Likewise, various variables with names like rnode and relnode get renamed appropriately, according to how they're being used in context. Hopefully, this is clearer than before. It is also preparation for future patches that intend to widen the relfilenumber fields from its current width of 32 bits. Variables that store a relfilenumber are now declared as type RelFileNumber rather than type Oid; right now, these are the same, but that can now more easily be changed. Dilip Kumar, per an idea from me. Reviewed also by Andres Freund. I fixed some whitespace issues, changed a couple of words in a comment, and made one other minor correction. Discussion: http://postgr.es/m/CA+TgmoamOtXbVAQf9hWFzonUo6bhhjS6toZQd7HZ-pmojtAmag@mail.gmail.com Discussion: http://postgr.es/m/CA+Tgmobp7+7kmi4gkq7Y+4AM9fTvL+O1oQ4-5gFTT+6Ng-dQ=g@mail.gmail.com Discussion: http://postgr.es/m/CAFiTN-vTe79M8uDH1yprOU64MNFE+R3ODRuA+JWf27JbhY4hJw@mail.gmail.com
2022-07-06 17:39:09 +02:00
#include "storage/relfilelocator.h"
Refactor the fsync queue for wider use. Previously, md.c and checkpointer.c were tightly integrated so that fsync calls could be handed off and processed in the background. Introduce a system of callbacks and file tags, so that other modules can hand off fsync work in the same way. For now only md.c uses the new interface, but other users are being proposed. Since there may be use cases that are not strictly SMGR implementations, use a new function table for sync handlers rather than extending the traditional SMGR one. Instead of using a bitmapset of segment numbers for each RelFileNode in the checkpointer's hash table, make the segment number part of the key. This requires sending explicit "forget" requests for every segment individually when relations are dropped, but suits the file layout schemes of proposed future users better (ie sparse or high segment numbers). Author: Shawn Debnath and Thomas Munro Reviewed-by: Thomas Munro, Andres Freund Discussion: https://postgr.es/m/CAEepm=2gTANm=e3ARnJT=n0h8hf88wqmaZxk0JYkxw+b21fNrw@mail.gmail.com
2019-04-04 10:56:03 +02:00
#include "storage/smgr.h"
#include "storage/sync.h"
Per previous discussions, get rid of use of sync(2) in favor of explicitly fsync'ing every (non-temp) file we have written since the last checkpoint. In the vast majority of cases, the burden of the fsyncs should fall on the bgwriter process not on backends. (To this end, we assume that an fsync issued by the bgwriter will force out blocks written to the same file by other processes using other file descriptors. Anyone have a problem with that?) This makes the world safe for WIN32, which ain't even got sync(2), and really makes the world safe for Unixen as well, because sync(2) never had the semantics we need: it offers no way to wait for the requested I/O to finish. Along the way, fix a bug I recently introduced in xlog recovery: file truncation replay failed to clear bufmgr buffers for the dropped blocks, which could result in 'PANIC: heap_delete_redo: no block' later on in xlog replay.
2004-05-31 05:48:10 +02:00
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
/* GUC options */
Apply PGDLLIMPORT markings broadly. Up until now, we've had a policy of only marking certain variables in the PostgreSQL header files with PGDLLIMPORT, but now we've decided to mark them all. This means that extensions running on Windows should no longer operate at a disadvantage as compared to extensions running on Linux: if the variable is present in a header file, it should be accessible. Discussion: http://postgr.es/m/CA+TgmoYanc1_FSfimhgiWSqVyP5KKmh5NP2BWNwDhO8Pg2vGYQ@mail.gmail.com
2022-04-08 14:16:38 +02:00
extern PGDLLIMPORT int BgWriterDelay;
extern PGDLLIMPORT int CheckPointTimeout;
extern PGDLLIMPORT int CheckPointWarning;
extern PGDLLIMPORT double CheckPointCompletionTarget;
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
Add macros wrapping all usage of gcc's __attribute__. Until now __attribute__() was defined to be empty for all compilers but gcc. That's problematic because it prevents using it in other compilers; which is necessary e.g. for atomics portability. It's also just generally dubious to do so in a header as widely included as c.h. Instead add pg_attribute_format_arg, pg_attribute_printf, pg_attribute_noreturn macros which are implemented in the compilers that understand them. Also add pg_attribute_noreturn and pg_attribute_packed, but don't provide fallbacks, since they can affect functionality. This means that external code that, possibly unwittingly, relied on __attribute__ defined to be empty on !gcc compilers may now run into warnings or errors on those compilers. But there shouldn't be many occurances of that and it's hard to work around... Discussion: 54B58BA3.8040302@ohmu.fi Author: Oskari Saarenmaa, with some minor changes by me.
2015-03-11 14:19:54 +01:00
extern void BackgroundWriterMain(void) pg_attribute_noreturn();
extern void CheckpointerMain(void) pg_attribute_noreturn();
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
Implement "distributed" checkpoints in which the checkpoint I/O is spread over a fairly long period of time, rather than being spat out in a burst. This happens only for background checkpoints carried out by the bgwriter; other cases, such as a shutdown checkpoint, are still done at full speed. Remove the "all buffers" scan in the bgwriter, and associated stats infrastructure, since this seems no longer very useful when the checkpoint itself is properly throttled. Original patch by Itagaki Takahiro, reworked by Heikki Linnakangas, and some minor API editorialization by me.
2007-06-28 02:02:40 +02:00
extern void RequestCheckpoint(int flags);
extern void CheckpointWriteDelay(int flags, double progress);
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
Refactor the fsync queue for wider use. Previously, md.c and checkpointer.c were tightly integrated so that fsync calls could be handed off and processed in the background. Introduce a system of callbacks and file tags, so that other modules can hand off fsync work in the same way. For now only md.c uses the new interface, but other users are being proposed. Since there may be use cases that are not strictly SMGR implementations, use a new function table for sync handlers rather than extending the traditional SMGR one. Instead of using a bitmapset of segment numbers for each RelFileNode in the checkpointer's hash table, make the segment number part of the key. This requires sending explicit "forget" requests for every segment individually when relations are dropped, but suits the file layout schemes of proposed future users better (ie sparse or high segment numbers). Author: Shawn Debnath and Thomas Munro Reviewed-by: Thomas Munro, Andres Freund Discussion: https://postgr.es/m/CAEepm=2gTANm=e3ARnJT=n0h8hf88wqmaZxk0JYkxw+b21fNrw@mail.gmail.com
2019-04-04 10:56:03 +02:00
extern bool ForwardSyncRequest(const FileTag *ftag, SyncRequestType type);
extern void AbsorbSyncRequests(void);
Per previous discussions, get rid of use of sync(2) in favor of explicitly fsync'ing every (non-temp) file we have written since the last checkpoint. In the vast majority of cases, the burden of the fsyncs should fall on the bgwriter process not on backends. (To this end, we assume that an fsync issued by the bgwriter will force out blocks written to the same file by other processes using other file descriptors. Anyone have a problem with that?) This makes the world safe for WIN32, which ain't even got sync(2), and really makes the world safe for Unixen as well, because sync(2) never had the semantics we need: it offers no way to wait for the requested I/O to finish. Along the way, fix a bug I recently introduced in xlog recovery: file truncation replay failed to clear bufmgr buffers for the dropped blocks, which could result in 'PANIC: heap_delete_redo: no block' later on in xlog replay.
2004-05-31 05:48:10 +02:00
Rename BgWriterShmem/Request to CheckpointerShmem/Request
2012-05-09 15:23:45 +02:00
extern Size CheckpointerShmemSize(void);
extern void CheckpointerShmemInit(void);
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
After any checkpoint, close all smgr files handles in bgwriter
2012-06-01 10:24:53 +02:00
extern bool FirstCallSinceLastCheckpoint(void);
Separate out bgwriter code into a logically separate module, rather than being random pieces of other files. Give bgwriter responsibility for all checkpoint activity (other than a post-recovery checkpoint); so this child process absorbs the functionality of the former transient checkpoint and shutdown subprocesses. While at it, create an actual include file for postmaster.c, which for some reason never had its own file before.
2004-05-30 00:48:23 +02:00
#endif /* _BGWRITER_H */