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path: root/src/backend/storage/ipc/sinvaladt.c
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* Pre-beta mechanical code beautification.Tom Lane2022-05-12
| | | | | Run pgindent, pgperltidy, and reformat-dat-files. I manually fixed a couple of comments that pgindent uglified.
* Revert the addition of GetMaxBackends() and related stuff.Robert Haas2022-04-12
| | | | | | | | | | | | This reverts commits 0147fc7, 4567596, aa64f23, and 5ecd018. There is no longer agreement that introducing this function was the right way to address the problem. The consensus now seems to favor trying to make a correct value for MaxBackends available to mdules executing their _PG_init() functions. Nathan Bossart Discussion: http://postgr.es/m/20220323045229.i23skfscdbvrsuxa@jrouhaud
* Explain why the startup process can't cause a shortage of sinval slots.Robert Haas2022-03-29
| | | | | | | Bharath Rupireddy, reviewed by Fujii Masao and Yura Sokolov. Lightly edited by me. Discussion: http://postgr.es/m/CALj2ACU=3_frMkDp9UUeuZoAMjaK1y0Z_q5RFNbGvwi8NM==AA@mail.gmail.com
* Remove MaxBackends variable in favor of GetMaxBackends() function.Robert Haas2022-02-08
| | | | | | | | | | | | | | Previously, it was really easy to write code that accessed MaxBackends before we'd actually initialized it, especially when coding up an extension. To make this less error-prune, introduce a new function GetMaxBackends() which should be used to obtain the correct value. This will ERROR if called too early. Demote the global variable to a file-level static, so that nobody can peak at it directly. Nathan Bossart. Idea by Andres Freund. Review by Greg Sabino Mullane, by Michael Paquier (who had doubts about the approach), and by me. Discussion: http://postgr.es/m/20210802224204.bckcikl45uezv5e4@alap3.anarazel.de
* Update copyright for 2022Bruce Momjian2022-01-07
| | | | Backpatch-through: 10
* Update copyright for 2021Bruce Momjian2021-01-02
| | | | Backpatch-through: 9.5
* snapshot scalability: Introduce dense array of in-progress xids.Andres Freund2020-08-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The new array contains the xids for all connected backends / in-use PGPROC entries in a dense manner (in contrast to the PGPROC/PGXACT arrays which can have unused entries interspersed). This improves performance because GetSnapshotData() always needs to scan the xids of all live procarray entries and now there's no need to go through the procArray->pgprocnos indirection anymore. As the set of running top-level xids changes rarely, compared to the number of snapshots taken, this substantially increases the likelihood of most data required for a snapshot being in l2 cache. In read-mostly workloads scanning the xids[] array will sufficient to build a snapshot, as most backends will not have an xid assigned. To keep the xid array dense ProcArrayRemove() needs to move entries behind the to-be-removed proc's one further up in the array. Obviously moving array entries cannot happen while a backend sets it xid. I.e. locking needs to prevent that array entries are moved while a backend modifies its xid. To avoid locking ProcArrayLock in GetNewTransactionId() - a fairly hot spot already - ProcArrayAdd() / ProcArrayRemove() now needs to hold XidGenLock in addition to ProcArrayLock. Adding / Removing a procarray entry is not a very frequent operation, even taking 2PC into account. Due to the above, the dense array entries can only be read or modified while holding ProcArrayLock and/or XidGenLock. This prevents a concurrent ProcArrayRemove() from shifting the dense array while it is accessed concurrently. While the new dense array is very good when needing to look at all xids it is less suitable when accessing a single backend's xid. In particular it would be problematic to have to acquire a lock to access a backend's own xid. Therefore a backend's xid is not just stored in the dense array, but also in PGPROC. This also allows a backend to only access the shared xid value when the backend had acquired an xid. The infrastructure added in this commit will be used for the remaining PGXACT fields in subsequent commits. They are kept separate to make review easier. Author: Andres Freund <andres@anarazel.de> Reviewed-By: Robert Haas <robertmhaas@gmail.com> Reviewed-By: Thomas Munro <thomas.munro@gmail.com> Reviewed-By: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/20200301083601.ews6hz5dduc3w2se@alap3.anarazel.de
* snapshot scalability: Move PGXACT->xmin back to PGPROC.Andres Freund2020-08-13
| | | | | | | | | | | | | | | | | | | | | | Now that xmin isn't needed for GetSnapshotData() anymore, it leads to unnecessary cacheline ping-pong to have it in PGXACT, as it is updated considerably more frequently than the other PGXACT members. After the changes in dc7420c2c92, this is a very straight-forward change. For highly concurrent, snapshot acquisition heavy, workloads this change alone can significantly increase scalability. E.g. plain pgbench on a smaller 2 socket machine gains 1.07x for read-only pgbench, 1.22x for read-only pgbench when submitting queries in batches of 100, and 2.85x for batches of 100 'SELECT';. The latter numbers are obviously not to be expected in the real-world, but micro-benchmark the snapshot computation scalability (previously spending ~80% of the time in GetSnapshotData()). Author: Andres Freund <andres@anarazel.de> Reviewed-By: Robert Haas <robertmhaas@gmail.com> Reviewed-By: Thomas Munro <thomas.munro@gmail.com> Reviewed-By: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/20200301083601.ews6hz5dduc3w2se@alap3.anarazel.de
* Update copyrights for 2020Bruce Momjian2020-01-01
| | | | Backpatch-through: update all files in master, backpatch legal files through 9.4
* Make the order of the header file includes consistent in backend modules.Amit Kapila2019-11-12
| | | | | | | | | | | Similar to commits 7e735035f2 and dddf4cdc33, this commit makes the order of header file inclusion consistent for backend modules. In the passing, removed a couple of duplicate inclusions. Author: Vignesh C Reviewed-by: Kuntal Ghosh and Amit Kapila Discussion: https://postgr.es/m/CALDaNm2Sznv8RR6Ex-iJO6xAdsxgWhCoETkaYX=+9DW3q0QCfA@mail.gmail.com
* Update copyright for 2019Bruce Momjian2019-01-02
| | | | Backpatch-through: certain files through 9.4
* Update copyright for 2018Bruce Momjian2018-01-02
| | | | Backpatch-through: certain files through 9.3
* Change TRUE/FALSE to true/falsePeter Eisentraut2017-11-08
| | | | | | | | | | | | | | The lower case spellings are C and C++ standard and are used in most parts of the PostgreSQL sources. The upper case spellings are only used in some files/modules. So standardize on the standard spellings. The APIs for ICU, Perl, and Windows define their own TRUE and FALSE, so those are left as is when using those APIs. In code comments, we use the lower-case spelling for the C concepts and keep the upper-case spelling for the SQL concepts. Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
* Phase 2 of pgindent updates.Tom Lane2017-06-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
* Update copyright via script for 2017Bruce Momjian2017-01-03
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* Update copyright for 2016Bruce Momjian2016-01-02
| | | | Backpatch certain files through 9.1
* Remove volatile qualifiers from dynahash.c, shmem.c, and sinvaladt.cRobert Haas2015-10-16
| | | | | | | | Prior to commit 0709b7ee72e4bc71ad07b7120acd117265ab51d0, access to variables within a spinlock-protected critical section had to be done through a volatile pointer, but that should no longer be necessary. Thomas Munro
* Fix rare core dump in BackendIdGetTransactionIds().Tom Lane2015-03-30
| | | | | | | | | | BackendIdGetTransactionIds() neglected the possibility that the PROC pointer in a ProcState array entry is null. In current usage, this could only crash if the other backend had exited since pgstat_read_current_status saw it as active, which is a pretty narrow window. But it's reachable in the field, per bug #12918 from Vladimir Borodin. Back-patch to 9.4 where the faulty code was introduced.
* Use FLEXIBLE_ARRAY_MEMBER in a number of other places.Tom Lane2015-02-21
| | | | I think we're about done with this...
* Update copyright for 2015Bruce Momjian2015-01-06
| | | | Backpatch certain files through 9.0
* pgindent run for 9.4Bruce Momjian2014-05-06
| | | | | This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
* Show xid and xmin in pg_stat_activity and pg_stat_replication.Robert Haas2014-02-25
| | | | | Christian Kruse, reviewed by Andres Freund and myself, with further minor adjustments by me.
* Update copyright for 2014Bruce Momjian2014-01-07
| | | | | Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.
* Fix typo in comment.Fujii Masao2013-07-31
| | | | Hitoshi Harada
* Update copyrights for 2013Bruce Momjian2013-01-01
| | | | | Fully update git head, and update back branches in ./COPYRIGHT and legal.sgml files.
* Run pgindent on 9.2 source tree in preparation for first 9.3Bruce Momjian2012-06-10
| | | | commit-fest.
* Update copyright notices for year 2012.Bruce Momjian2012-01-01
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* Create VXID locks "lazily" in the main lock table.Robert Haas2011-08-04
| | | | | | | | | | | | | Instead of entering them on transaction startup, we materialize them only when someone wants to wait, which will occur only during CREATE INDEX CONCURRENTLY. In Hot Standby mode, the startup process must also be able to probe for conflicting VXID locks, but the lock need never be fully materialized, because the startup process does not use the normal lock wait mechanism. Since most VXID locks never need to touch the lock manager partition locks, this can significantly reduce blocking contention on read-heavy workloads. Patch by me. Review by Jeff Davis.
* Minor stylistic corrections.Robert Haas2011-08-01
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* Reduce sinval synchronization overhead.Robert Haas2011-07-29
| | | | | | | | | | | Testing shows that the overhead of acquiring and releasing SInvalReadLock and msgNumLock on high-core count boxes can waste a lot of CPU time and hurt performance. This patch adds a per-backend flag that allows us to skip all that locking in most cases. Further testing shows that this improves performance even when sinval traffic is very high. Patch by me. Review and testing by Noah Misch.
* Capitalization fixesPeter Eisentraut2011-06-19
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* Stamp copyrights for year 2011.Bruce Momjian2011-01-01
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* Remove cvs keywords from all files.Magnus Hagander2010-09-20
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* pgindent run for 9.0Bruce Momjian2010-02-26
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* Update copyright for the year 2010.Bruce Momjian2010-01-02
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* Allow read only connections during recovery, known as Hot Standby.Simon Riggs2009-12-19
| | | | | | | | | | | | Enabled by recovery_connections = on (default) and forcing archive recovery using a recovery.conf. Recovery processing now emulates the original transactions as they are replayed, providing full locking and MVCC behaviour for read only queries. Recovery must enter consistent state before connections are allowed, so there is a delay, typically short, before connections succeed. Replay of recovering transactions can conflict and in some cases deadlock with queries during recovery; these result in query cancellation after max_standby_delay seconds have expired. Infrastructure changes have minor effects on normal running, though introduce four new types of WAL record. New test mode "make standbycheck" allows regression tests of static command behaviour on a standby server while in recovery. Typical and extreme dynamic behaviours have been checked via code inspection and manual testing. Few port specific behaviours have been utilised, though primary testing has been on Linux only so far. This commit is the basic patch. Additional changes will follow in this release to enhance some aspects of behaviour, notably improved handling of conflicts, deadlock detection and query cancellation. Changes to VACUUM FULL are also required. Simon Riggs, with significant and lengthy review by Heikki Linnakangas, including streamlined redesign of snapshot creation and two-phase commit. Important contributions from Florian Pflug, Mark Kirkwood, Merlin Moncure, Greg Stark, Gianni Ciolli, Gabriele Bartolini, Hannu Krosing, Robert Haas, Tatsuo Ishii, Hiroyuki Yamada plus support and feedback from many other community members.
* Create a multiplexing structure for signals to Postgres child processes.Tom Lane2009-07-31
| | | | | | | | | | | | | | | This patch gets us out from under the Unix limitation of two user-defined signal types. We already had done something similar for signals directed to the postmaster process; this adds multiplexing for signals directed to backends and auxiliary processes (so long as they're connected to shared memory). As proof of concept, replace the former usage of SIGUSR1 and SIGUSR2 for backends with use of the multiplexing mechanism. There are still some hard-wired definitions of SIGUSR1 and SIGUSR2 for other process types, but getting rid of those doesn't seem interesting at the moment. Fujii Masao
* 8.4 pgindent run, with new combined Linux/FreeBSD/MinGW typedef listBruce Momjian2009-06-11
| | | | provided by Andrew.
* Update copyright for 2009.Bruce Momjian2009-01-01
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* Revert SIGUSR1 multiplexing patch, per Tom's objection.Heikki Linnakangas2008-12-09
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* Provide support for multiplexing SIGUSR1 signal. The upcoming synchronousHeikki Linnakangas2008-12-09
| | | | | | replication patch needs a signal, but we've already used SIGUSR1 and SIGUSR2 in normal backends. This patch allows reusing SIGUSR1 for that, and for other purposes too if the need arises.
* Fix a race condition that I introduced into sinvaladt.c during the recentTom Lane2008-07-18
| | | | | | | | | rewrite. When called from SIInsertDataEntries, SICleanupQueue releases the write lock if it has to issue a kill() to signal some laggard backend. That still seems like a good idea --- but it's possible that by the time we get the lock back, there are no longer enough free message slots to satisfy SIInsertDataEntries' requirement. Must recheck, and repeat the whole SICleanupQueue process if not. Noted while reading code.
* Teach autovacuum how to determine whether a temp table belongs to a crashedTom Lane2008-07-01
| | | | | | | backend. If so, send a LOG message to the postmaster log, and if the table is beyond the vacuum-for-wraparound horizon, forcibly drop it. Per recent discussions. Perhaps we ought to back-patch this, but it probably needs to age a bit in HEAD first.
* Seems I was too optimistic in supposing that sinval's maxMsgNum could beTom Lane2008-06-20
| | | | | | | | | | | read and written without a lock. The value itself is atomic, sure, but on processors with weak memory ordering it's possible for a reader to see the value change before it sees the associated message written into the buffer array. Fix by introducing a spinlock that's used just to read and write maxMsgNum. (We could do this with less overhead if we recognized a concept of "memory access barrier"; is it worth introducing such a thing? At the moment probably not --- I can't measure any clear slowdown from adding the spinlock, so this solution is probably fine.) Per buildfarm results.
* Rewrite the sinval messaging mechanism to reduce contention and avoidTom Lane2008-06-19
| | | | | | | | | | | | | | | | | | | | | | | | | | unnecessary cache resets. The major changes are: * When the queue overflows, we only issue a cache reset to the specific backend or backends that still haven't read the oldest message, rather than resetting everyone as in the original coding. * When we observe backend(s) falling well behind, we signal SIGUSR1 to only one backend, the one that is furthest behind and doesn't already have a signal outstanding for it. When it finishes catching up, it will in turn signal SIGUSR1 to the next-furthest-back guy, if there is one that is far enough behind to justify a signal. The PMSIGNAL_WAKEN_CHILDREN mechanism is removed. * We don't attempt to clean out dead messages after every message-receipt operation; rather, we do it on the insertion side, and only when the queue fullness passes certain thresholds. * Split SInvalLock into SInvalReadLock and SInvalWriteLock so that readers don't block writers nor vice versa (except during the infrequent queue cleanout operations). * Transfer multiple sinval messages for each acquisition of a read or write lock.
* Remove freeBackends counter from the sinval shared memory area. We used toTom Lane2008-06-17
| | | | | use it to help enforce superuser_reserved_backends, but since 8.1 it's just been dead weight.
* Move elog(DEBUG4) call outside the locked area, per suggestion from Tom Lane.Alvaro Herrera2008-03-18
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* Move ProcState definition into sinvaladt.c from sinvaladt.h, since it's notAlvaro Herrera2008-03-17
| | | | | | needed anywhere after my previous patch. Noticed by Tom Lane. Also, remove #include <signal.h> from sinval.c.
* Modify interactions between sinval.c and sinvaladt.c. The code that actuallyAlvaro Herrera2008-03-16
| | | | | | | | deals with the queue, including locking etc, is all in sinvaladt.c. This means that the struct definition of the queue, and the queue pointer, are now internal "implementation details" inside sinvaladt.c. Per my proposal dated 25-Jun-2007 and followup discussion.
* Update copyrights in source tree to 2008.Bruce Momjian2008-01-01
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