I think attached v18 addresses all outstanding issues except a run
through the docs making sure all mentions of the balancing algorithm are
still correct.
On Wed, Apr 5, 2023 at 9:10 AM Daniel Gustafsson <dan...@yesql.se> wrote:
> > On 4 Apr 2023, at 22:04, Melanie Plageman <melanieplage...@gmail.com> wrote:
> >> +extern int VacuumCostLimit;
> >> +extern double VacuumCostDelay;
> >> ...
> >> -extern PGDLLIMPORT int VacuumCostLimit;
> >> -extern PGDLLIMPORT double VacuumCostDelay;
> >>
> >> Same with these, I don't think this is according to our default visibility.
> >> Moreover, I'm not sure it's a good idea to perform this rename. This will
> >> keep
> >> VacuumCostLimit and VacuumCostDelay exported, but change their meaning.
> >> Any
> >> external code referring to these thinking they are backing the GUCs will
> >> still
> >> compile, but may be broken in subtle ways. Is there a reason for not
> >> keeping
> >> the current GUC variables and instead add net new ones?
> >
> > When VacuumCostLimit was the same variable in the code and for the GUC
> > vacuum_cost_limit, everytime we reload the config file, VacuumCostLimit
> > is overwritten. Autovacuum workers have to overwrite this value with the
> > appropriate one for themselves given the balancing logic and the value
> > of autovacuum_vacuum_cost_limit. However, the problem is, because you
> > can specify -1 for autovacuum_vacuum_cost_limit to indicate it should
> > fall back to vacuum_cost_limit, we have to reference the value of
> > VacuumCostLimit when calculating the new autovacuum worker's cost limit
> > after a config reload.
> >
> > But, you have to be sure you *only* do this after a config reload when
> > the value of VacuumCostLimit is fresh and unmodified or you risk
> > dividing the value of VacuumCostLimit over and over. That means it is
> > unsafe to call functions updating the cost limit more than once.
> >
> > This orchestration wasn't as difficult when we only reloaded the config
> > file once every table. We were careful about it and also kept the
> > original "base" cost limit around from table_recheck_autovac(). However,
> > once we started reloading the config file more often, this no longer
> > works.
> >
> > By separating the variables modified when the gucs are set and the ones
> > used the code, we can make sure we always have the original value the
> > guc was set to in vacuum_cost_limit and autovacuum_vacuum_cost_limit,
> > whenever we need to reference it.
> >
> > That being said, perhaps we should document what extensions should do?
> > Do you think they will want to use the variables backing the gucs or to
> > be able to overwrite the variables being used in the code?
>
> I think I wasn't clear in my comment, sorry. I don't have a problem with
> introducing a new variable to split the balanced value from the GUC value.
> What I don't think we should do is repurpose an exported symbol into doing a
> new thing. In the case at hand I think VacuumCostLimit and VacuumCostDelay
> should remain the backing variables for the GUCs, with vacuum_cost_limit and
> vacuum_cost_delay carrying the balanced values. So the inverse of what is in
> the patch now.
>
> The risk of these symbols being used in extensions might be very low but on
> principle it seems unwise to alter a symbol and risk subtle breakage.
In attached v18, I have flipped them. Existing (in master) GUCs which
were exported for VacuumCostLimit and VacuumCostDelay retain their names
and new globals vacuum_cost_limit and vacuum_cost_delay have been
introduced for use in the code.
Flipping these kind of melted my mind, so I could definitely use another
set of eyes double checking that the correct ones are being used in the
correct places throughout 0002 and 0003.
On Thu, Apr 6, 2023 at 3:09 PM Melanie Plageman
<melanieplage...@gmail.com> wrote:
>
> v17 attached does not yet fix the logging problem or variable naming
> problem.
>
> I have not changed where AutoVacuumUpdateCostLimit() is called either.
>
> This is effectively just a round of cleanup. I hope I have managed to
> address all other code review feedback so far, though some may have
> slipped through the cracks.
>
> On Wed, Apr 5, 2023 at 2:56 PM Robert Haas <robertmh...@gmail.com> wrote:
> > On Wed, Apr 5, 2023 at 11:29 AM Melanie Plageman
> > <melanieplage...@gmail.com> wrote:
> > + /*
> > + * Balance and update limit values for autovacuum workers. We must
> > + * always do this in case the autovacuum launcher or another
> > + * autovacuum worker has recalculated the number of workers across
> > + * which we must balance the limit. This is done by the launcher when
> > + * launching a new worker and by workers before vacuuming each table.
> > + */
> >
> > I don't quite understand what's going on here. A big reason that I'm
> > worried about this whole issue in the first place is that sometimes
> > there's a vacuum going on a giant table and you can't get it to go
> > fast. You want it to absorb new settings, and to do so quickly. I
> > realize that this is about the number of workers, not the actual cost
> > limit, so that makes what I'm about to say less important. But ... is
> > this often enough? Like, the time before we move onto the next table
> > could be super long. The time before a new worker is launched should
> > be ~autovacuum_naptime/autovacuum_max_workers or ~20s with default
> > settings, so that's not horrible, but I'm kind of struggling to
> > understand the rationale for this particular choice. Maybe it's fine.
>
> I've at least updated this comment to be more correct/less misleading.
>
> >
> > + if (autovacuum_vac_cost_limit > 0)
> > + VacuumCostLimit = autovacuum_vac_cost_limit;
> > + else
> > + VacuumCostLimit = vacuum_cost_limit;
> > +
> > + /* Only balance limit if no cost-related storage
> > parameters specified */
> > + if
> > (pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance))
> > + return;
> > + Assert(VacuumCostLimit > 0);
> > +
> > + nworkers_for_balance = pg_atomic_read_u32(
> > +
> > &AutoVacuumShmem->av_nworkersForBalance);
> > +
> > + /* There is at least 1 autovac worker (this worker). */
> > + if (nworkers_for_balance <= 0)
> > + elog(ERROR, "nworkers_for_balance must be > 0");
> > +
> > + VacuumCostLimit = Max(VacuumCostLimit /
> > nworkers_for_balance, 1);
> >
> > I think it would be better stylistically to use a temporary variable
> > here and only assign the final value to VacuumCostLimit.
>
> I tried that and thought it adding confusing clutter. If it is a code
> cleanliness issue, I am willing to change it, though.
>
> On Wed, Apr 5, 2023 at 3:04 PM Daniel Gustafsson <dan...@yesql.se> wrote:
> >
> > > On 5 Apr 2023, at 20:55, Robert Haas <robertmh...@gmail.com> wrote:
> >
> > > Again, I don't think this is something we should try to
> > > address right now under time pressure, but in the future, I think we
> > > should consider ripping this behavior out.
> >
> > I would not be opposed to that, but I wholeheartedly agree that it's not the
> > job of this patch (or any patch at this point in the cycle).
> >
> > > + if (autovacuum_vac_cost_limit > 0)
> > > + VacuumCostLimit = autovacuum_vac_cost_limit;
> > > + else
> > > + VacuumCostLimit = vacuum_cost_limit;
> > > +
> > > + /* Only balance limit if no cost-related storage
> > > parameters specified */
> > > + if
> > > (pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance))
> > > + return;
> > > + Assert(VacuumCostLimit > 0);
> > > +
> > > + nworkers_for_balance = pg_atomic_read_u32(
> > > +
> > > &AutoVacuumShmem->av_nworkersForBalance);
> > > +
> > > + /* There is at least 1 autovac worker (this worker). */
> > > + if (nworkers_for_balance <= 0)
> > > + elog(ERROR, "nworkers_for_balance must be > 0");
> > > +
> > > + VacuumCostLimit = Max(VacuumCostLimit /
> > > nworkers_for_balance, 1);
> > >
> > > I think it would be better stylistically to use a temporary variable
> > > here and only assign the final value to VacuumCostLimit.
> >
> > I can agree with that. Another supertiny nitpick on the above is to not
> > end a
> > single-line comment with a period.
>
> I have fixed this.
>
> On Thu, Apr 6, 2023 at 2:40 AM Masahiko Sawada <sawada.m...@gmail.com> wrote:
> >
> > On Thu, Apr 6, 2023 at 12:29 AM Melanie Plageman
> > <melanieplage...@gmail.com> wrote:
> > >
> > > Thanks all for the reviews.
> > >
> > > v16 attached. I put it together rather quickly, so there might be a few
> > > spurious whitespaces or similar. There is one rather annoying pgindent
> > > outlier that I have to figure out what to do about as well.
> > >
> > > The remaining functional TODOs that I know of are:
> > >
> > > - Resolve what to do about names of GUC and vacuum variables for cost
> > > limit and cost delay (since it may affect extensions)
> > >
> > > - Figure out what to do about the logging message which accesses dboid
> > > and tableoid (lock/no lock, where to put it, etc)
> > >
> > > - I see several places in docs which reference the balancing algorithm
> > > for autovac workers. I did not read them in great detail, but we may
> > > want to review them to see if any require updates.
> > >
> > > - Consider whether or not the initial two commits should just be
> > > squashed with the third commit
> > >
> > > - Anything else reviewers are still unhappy with
> > >
> > >
> > > On Wed, Apr 5, 2023 at 1:56 AM Masahiko Sawada <sawada.m...@gmail.com>
> > > wrote:
> > > >
> > > > On Wed, Apr 5, 2023 at 5:05 AM Melanie Plageman
> > > > <melanieplage...@gmail.com> wrote:
> > > > >
> > > > > On Tue, Apr 4, 2023 at 4:27 AM Masahiko Sawada
> > > > > <sawada.m...@gmail.com> wrote:
> > > > > > ---
> > > > > > - if (worker->wi_proc != NULL)
> > > > > > - elog(DEBUG2, "autovac_balance_cost(pid=%d
> > > > > > db=%u, rel=%u, dobalance=%s cost_limit=%d, cost_limit_base=%d,
> > > > > > cost_delay=%g)",
> > > > > > - worker->wi_proc->pid,
> > > > > > worker->wi_dboid, worker->wi_tableoid,
> > > > > > - worker->wi_dobalance ? "yes" :
> > > > > > "no",
> > > > > > - worker->wi_cost_limit,
> > > > > > worker->wi_cost_limit_base,
> > > > > > - worker->wi_cost_delay);
> > > > > >
> > > > > > I think it's better to keep this kind of log in some form for
> > > > > > debugging. For example, we can show these values of autovacuum
> > > > > > workers
> > > > > > in VacuumUpdateCosts().
> > > > >
> > > > > I added a message to do_autovacuum() after calling VacuumUpdateCosts()
> > > > > in the loop vacuuming each table. That means it will happen once per
> > > > > table. It's not ideal that I had to move the call to
> > > > > VacuumUpdateCosts()
> > > > > behind the shared lock in that loop so that we could access the pid
> > > > > and
> > > > > such in the logging message after updating the cost and delay, but it
> > > > > is
> > > > > probably okay. Though noone is going to be changing those at this
> > > > > point, it still seemed better to access them under the lock.
> > > > >
> > > > > This does mean we won't log anything when we do change the values of
> > > > > VacuumCostDelay and VacuumCostLimit while vacuuming a table. Is it
> > > > > worth
> > > > > adding some code to do that in VacuumUpdateCosts() (only when the
> > > > > value
> > > > > has changed not on every call to VacuumUpdateCosts())? Or perhaps we
> > > > > could add it in the config reload branch that is already in
> > > > > vacuum_delay_point()?
> > > >
> > > > Previously, we used to show the pid in the log since a worker/launcher
> > > > set other workers' delay costs. But now that the worker sets its delay
> > > > costs, we don't need to show the pid in the log. Also, I think it's
> > > > useful for debugging and investigating the system if we log it when
> > > > changing the values. The log I imagined to add was like:
> > > >
> > > > @@ -1801,6 +1801,13 @@ VacuumUpdateCosts(void)
> > > > VacuumCostDelay = vacuum_cost_delay;
> > > >
> > > > AutoVacuumUpdateLimit();
> > > > +
> > > > + elog(DEBUG2, "autovacuum update costs (db=%u, rel=%u,
> > > > dobalance=%s, cost_limit=%d, cost_delay=%g active=%s failsafe=%s)",
> > > > + MyWorkerInfo->wi_dboid, MyWorkerInfo->wi_tableoid,
> > > > + pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance)
> > > > ? "no" : "yes",
> > > > + VacuumCostLimit, VacuumCostDelay,
> > > > + VacuumCostDelay > 0 ? "yes" : "no",
> > > > + VacuumFailsafeActive ? "yes" : "no");
> > > > }
> > > > else
> > > > {
> > >
> > > Makes sense. I've updated the log message to roughly what you suggested.
> > > I also realized I think it does make sense to call it in
> > > VacuumUpdateCosts() -- only for autovacuum workers of course. I've done
> > > this. I haven't taken the lock though and can't decide if I must since
> > > they access dboid and tableoid -- those are not going to change at this
> > > point, but I still don't know if I can access them lock-free...
> > > Perhaps there is a way to condition it on the log level?
> > >
> > > If I have to take a lock, then I don't know if we should put these in
> > > VacuumUpdateCosts()...
> >
> > I think we don't need to acquire a lock there as both values are
> > updated only by workers reporting this message.
>
> I dunno. I just don't feel that comfortable saying, oh it's okay to
> access these without a lock probably. I propose we do one of the
> following:
>
> - Take a shared lock inside VacuumUpdateCosts() (it is not called on every
> call to vacuum_delay_point()) before reading from these variables.
>
> Pros:
> - We will log whenever there is a change to these parameters
> Cons:
> - This adds overhead in the common case when log level is < DEBUG2.
> Is there a way to check the log level before taking the lock?
> - Acquiring the lock inside the function is inconsistent with the
> pattern that some of the other autovacuum functions requiring
> locks use (they assume you have a lock if needed inside of the
> function). But, we could assert that the lock is not already held.
> - If we later decide we don't like this choice and want to move the
> logging elsewhere, it will necessarily log less frequently which
> seems like a harder change to make than logging more frequently.
>
> - Move this logging into the loop through relations in do_autovacuum()
> and the config reload code and take the shared lock before doing the
> logging.
>
> Pros:
> - Seems safe and not expensive
> - Covers most of the times we would want the logging
> Cons:
> - duplicates logging in two places
Okay, in an attempt to wrap up this saga, I have made the following
change:
Autovacuum workers, at the end of VacuumUpdateCosts(), check if cost
limit or cost delay have been changed. If they have, they assert that
they don't already hold the AutovacuumLock, take it in shared mode, and
do the logging.
- Melanie
From 902ef92089d8b073be0d664fa5d5cc23624aa313 Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplage...@gmail.com>
Date: Sat, 25 Mar 2023 14:14:55 -0400
Subject: [PATCH v18 3/3] Autovacuum refreshes cost-based delay params more
often
Allow autovacuum to reload the config file more often so that cost-based
delay parameters can take effect while VACUUMing a relation. Previously,
autovacuum workers only reloaded the config file once per relation
vacuumed, so config changes could not take effect until beginning to
vacuum the next table.
Now, check if a reload is pending roughly once per block, when checking
if we need to delay.
In order for autovacuum workers to safely update their own cost delay
and cost limit parameters without impacting performance, we had to
rethink when and how these values were accessed.
Previously, an autovacuum worker's wi_cost_limit was set only at the
beginning of vacuuming a table, after reloading the config file.
Therefore, at the time that autovac_balance_cost() was called, workers
vacuuming tables with no cost-related storage parameters could still
have different values for their wi_cost_limit_base and wi_cost_delay.
Now that the cost parameters can be updated while vacuuming a table,
workers will (within some margin of error) have no reason to have
different values for cost limit and cost delay (in the absence of
cost-related storage parameters). This removes the rationale for keeping
cost limit and cost delay in shared memory. Balancing the cost limit
requires only the number of active autovacuum workers vacuuming a table
with no cost-based storage parameters.
Reviewed-by: Masahiko Sawada <sawada.m...@gmail.com>
Reviewed-by: Daniel Gustafsson <dan...@yesql.se>
Reviewed-by: Kyotaro Horiguchi <horikyota....@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAAKRu_ZngzqnEODc7LmS1NH04Kt6Y9huSjz5pp7%2BDXhrjDA0gw%40mail.gmail.com
---
src/backend/access/heap/vacuumlazy.c | 2 +-
src/backend/commands/vacuum.c | 46 +++-
src/backend/commands/vacuumparallel.c | 1 -
src/backend/postmaster/autovacuum.c | 289 +++++++++++++++-----------
src/include/commands/vacuum.h | 1 +
5 files changed, 217 insertions(+), 122 deletions(-)
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 2ba85bd3d6..0a9ebd22bd 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -389,7 +389,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
Assert(params->index_cleanup != VACOPTVALUE_UNSPECIFIED);
Assert(params->truncate != VACOPTVALUE_UNSPECIFIED &&
params->truncate != VACOPTVALUE_AUTO);
- VacuumFailsafeActive = false;
+ Assert(!VacuumFailsafeActive);
vacrel->consider_bypass_optimization = true;
vacrel->do_index_vacuuming = true;
vacrel->do_index_cleanup = true;
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index f2be74cdb5..ca347e0a6d 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -48,6 +48,7 @@
#include "pgstat.h"
#include "postmaster/autovacuum.h"
#include "postmaster/bgworker_internals.h"
+#include "postmaster/interrupt.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/pmsignal.h"
@@ -523,9 +524,9 @@ vacuum(List *relations, VacuumParams *params, BufferAccessStrategy bstrategy,
{
ListCell *cur;
- VacuumUpdateCosts();
in_vacuum = true;
- VacuumCostActive = (vacuum_cost_delay > 0);
+ VacuumFailsafeActive = false;
+ VacuumUpdateCosts();
VacuumCostBalance = 0;
VacuumPageHit = 0;
VacuumPageMiss = 0;
@@ -579,12 +580,20 @@ vacuum(List *relations, VacuumParams *params, BufferAccessStrategy bstrategy,
CommandCounterIncrement();
}
}
+
+ /*
+ * Ensure VacuumFailsafeActive has been reset before vacuuming the
+ * next relation.
+ */
+ VacuumFailsafeActive = false;
}
}
PG_FINALLY();
{
in_vacuum = false;
VacuumCostActive = false;
+ VacuumFailsafeActive = false;
+ VacuumCostBalance = 0;
}
PG_END_TRY();
@@ -2245,7 +2254,28 @@ vacuum_delay_point(void)
/* Always check for interrupts */
CHECK_FOR_INTERRUPTS();
- if (!VacuumCostActive || InterruptPending)
+ if (InterruptPending ||
+ (!VacuumCostActive && !ConfigReloadPending))
+ return;
+
+ /*
+ * Autovacuum workers should reload the configuration file if requested.
+ * This allows changes to [autovacuum_]vacuum_cost_limit and
+ * [autovacuum_]vacuum_cost_delay to take effect while a table is being
+ * vacuumed or analyzed.
+ */
+ if (ConfigReloadPending && IsAutoVacuumWorkerProcess())
+ {
+ ConfigReloadPending = false;
+ ProcessConfigFile(PGC_SIGHUP);
+ VacuumUpdateCosts();
+ }
+
+ /*
+ * If we disabled cost-based delays after reloading the config file,
+ * return.
+ */
+ if (!VacuumCostActive)
return;
/*
@@ -2278,7 +2308,15 @@ vacuum_delay_point(void)
VacuumCostBalance = 0;
- VacuumUpdateCosts();
+ /*
+ * Balance and update limit values for autovacuum workers. We must do
+ * this periodically, as the number of workers across which we are
+ * balancing the limit may have changed.
+ *
+ * XXX: There may be better criteria for determining when to do this
+ * besides "check after napping".
+ */
+ AutoVacuumUpdateCostLimit();
/* Might have gotten an interrupt while sleeping */
CHECK_FOR_INTERRUPTS();
diff --git a/src/backend/commands/vacuumparallel.c b/src/backend/commands/vacuumparallel.c
index cc0aff7904..e200d5caf8 100644
--- a/src/backend/commands/vacuumparallel.c
+++ b/src/backend/commands/vacuumparallel.c
@@ -995,7 +995,6 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
false);
/* Set cost-based vacuum delay */
- VacuumCostActive = (vacuum_cost_delay > 0);
VacuumUpdateCosts();
VacuumCostBalance = 0;
VacuumPageHit = 0;
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 3644b86443..8529324ebd 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -139,6 +139,18 @@ int Log_autovacuum_min_duration = 600000;
static bool am_autovacuum_launcher = false;
static bool am_autovacuum_worker = false;
+/*
+ * Variables to save the cost-related storage parameters for the current
+ * relation being vacuumed by this autovacuum worker. Using these, we can
+ * ensure we don't overwrite the values of vacuum_cost_delay and
+ * vacuum_cost_limit after reloading the configuration file. They are
+ * initialized to "invalid" values to indicate that no cost-related storage
+ * parameters were specified and will be set in do_autovacuum() after checking
+ * the storage parameters in table_recheck_autovac().
+ */
+static double av_storage_param_cost_delay = -1;
+static int av_storage_param_cost_limit = -1;
+
/* Flags set by signal handlers */
static volatile sig_atomic_t got_SIGUSR2 = false;
@@ -189,8 +201,8 @@ typedef struct autovac_table
{
Oid at_relid;
VacuumParams at_params;
- double at_vacuum_cost_delay;
- int at_vacuum_cost_limit;
+ double at_storage_param_vac_cost_delay;
+ int at_storage_param_vac_cost_limit;
bool at_dobalance;
bool at_sharedrel;
char *at_relname;
@@ -209,7 +221,7 @@ typedef struct autovac_table
* wi_sharedrel flag indicating whether table is marked relisshared
* wi_proc pointer to PGPROC of the running worker, NULL if not started
* wi_launchtime Time at which this worker was launched
- * wi_cost_* Vacuum cost-based delay parameters current in this worker
+ * wi_dobalance Whether this worker should be included in balance calculations
*
* All fields are protected by AutovacuumLock, except for wi_tableoid and
* wi_sharedrel which are protected by AutovacuumScheduleLock (note these
@@ -223,11 +235,8 @@ typedef struct WorkerInfoData
Oid wi_tableoid;
PGPROC *wi_proc;
TimestampTz wi_launchtime;
- bool wi_dobalance;
+ pg_atomic_flag wi_dobalance;
bool wi_sharedrel;
- double wi_cost_delay;
- int wi_cost_limit;
- int wi_cost_limit_base;
} WorkerInfoData;
typedef struct WorkerInfoData *WorkerInfo;
@@ -273,6 +282,8 @@ typedef struct AutoVacuumWorkItem
* av_startingWorker pointer to WorkerInfo currently being started (cleared by
* the worker itself as soon as it's up and running)
* av_workItems work item array
+ * av_nworkersForBalance the number of autovacuum workers to use when
+ * calculating the per worker cost limit
*
* This struct is protected by AutovacuumLock, except for av_signal and parts
* of the worker list (see above).
@@ -286,6 +297,7 @@ typedef struct
dlist_head av_runningWorkers;
WorkerInfo av_startingWorker;
AutoVacuumWorkItem av_workItems[NUM_WORKITEMS];
+ pg_atomic_uint32 av_nworkersForBalance;
} AutoVacuumShmemStruct;
static AutoVacuumShmemStruct *AutoVacuumShmem;
@@ -319,7 +331,7 @@ static void launch_worker(TimestampTz now);
static List *get_database_list(void);
static void rebuild_database_list(Oid newdb);
static int db_comparator(const void *a, const void *b);
-static void autovac_balance_cost(void);
+static void autovac_recalculate_workers_for_balance(void);
static void do_autovacuum(void);
static void FreeWorkerInfo(int code, Datum arg);
@@ -669,7 +681,7 @@ AutoVacLauncherMain(int argc, char *argv[])
{
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
AutoVacuumShmem->av_signal[AutoVacRebalance] = false;
- autovac_balance_cost();
+ autovac_recalculate_workers_for_balance();
LWLockRelease(AutovacuumLock);
}
@@ -818,11 +830,6 @@ HandleAutoVacLauncherInterrupts(void)
if (!AutoVacuumingActive())
AutoVacLauncherShutdown();
- /* rebalance in case the default cost parameters changed */
- LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
- autovac_balance_cost();
- LWLockRelease(AutovacuumLock);
-
/* rebuild the list in case the naptime changed */
rebuild_database_list(InvalidOid);
}
@@ -1754,10 +1761,7 @@ FreeWorkerInfo(int code, Datum arg)
MyWorkerInfo->wi_sharedrel = false;
MyWorkerInfo->wi_proc = NULL;
MyWorkerInfo->wi_launchtime = 0;
- MyWorkerInfo->wi_dobalance = false;
- MyWorkerInfo->wi_cost_delay = 0;
- MyWorkerInfo->wi_cost_limit = 0;
- MyWorkerInfo->wi_cost_limit_base = 0;
+ pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
&MyWorkerInfo->wi_links);
/* not mine anymore */
@@ -1781,10 +1785,20 @@ FreeWorkerInfo(int code, Datum arg)
void
VacuumUpdateCosts(void)
{
+ double original_cost_delay = vacuum_cost_delay;
+ int original_cost_limit = vacuum_cost_limit;
+
if (MyWorkerInfo)
{
- vacuum_cost_delay = MyWorkerInfo->wi_cost_delay;
- vacuum_cost_limit = MyWorkerInfo->wi_cost_limit;
+ if (av_storage_param_cost_delay >= 0)
+ vacuum_cost_delay = av_storage_param_cost_delay;
+ else if (autovacuum_vac_cost_delay >= 0)
+ vacuum_cost_delay = autovacuum_vac_cost_delay;
+ else
+ /* fall back to VacuumCostDelay */
+ vacuum_cost_delay = VacuumCostDelay;
+
+ AutoVacuumUpdateCostLimit();
}
else
{
@@ -1792,88 +1806,124 @@ VacuumUpdateCosts(void)
vacuum_cost_delay = VacuumCostDelay;
vacuum_cost_limit = VacuumCostLimit;
}
+
+ /*
+ * If configuration changes are allowed to impact VacuumCostActive, make
+ * sure it is updated.
+ */
+ if (VacuumFailsafeActive)
+ Assert(!VacuumCostActive);
+ else if (vacuum_cost_delay > 0)
+ VacuumCostActive = true;
+ else
+ {
+ VacuumCostActive = false;
+ VacuumCostBalance = 0;
+ }
+
+ if (MyWorkerInfo)
+ {
+ /* Only log updates to cost-related variables */
+ if (vacuum_cost_delay == original_cost_delay &&
+ vacuum_cost_limit == original_cost_limit)
+ return;
+
+ Assert(!LWLockHeldByMe(AutovacuumLock));
+
+ LWLockAcquire(AutovacuumLock, LW_SHARED);
+
+ elog(DEBUG2,
+ "Autovacuum VacuumUpdateCosts(db=%u, rel=%u, dobalance=%s, cost_limit=%d, cost_delay=%g active=%s failsafe=%s)",
+ MyWorkerInfo->wi_dboid, MyWorkerInfo->wi_tableoid,
+ pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance) ? "no" : "yes",
+ vacuum_cost_limit, vacuum_cost_delay,
+ vacuum_cost_delay > 0 ? "yes" : "no",
+ VacuumFailsafeActive ? "yes" : "no");
+
+ LWLockRelease(AutovacuumLock);
+ }
}
/*
- * autovac_balance_cost
- * Recalculate the cost limit setting for each active worker.
- *
- * Caller must hold the AutovacuumLock in exclusive mode.
+ * Update vacuum_cost_limit with the correct value for an autovacuum worker,
+ * given the value of other relevant cost limit parameters and the number of
+ * workers across which the limit must be balanced. Autovacuum workers must
+ * call this regularly in case av_nworkersForBalance has been updated by
+ * another worker or by the autovacuum launcher. They must also call it after a
+ * config reload.
*/
-static void
-autovac_balance_cost(void)
+void
+AutoVacuumUpdateCostLimit(void)
{
+ if (!MyWorkerInfo)
+ return;
+
/*
- * The idea here is that we ration out I/O equally. The amount of I/O
- * that a worker can consume is determined by cost_limit/cost_delay, so we
- * try to equalize those ratios rather than the raw limit settings.
- *
* note: in cost_limit, zero also means use value from elsewhere, because
* zero is not a valid value.
*/
- int vac_cost_limit = (autovacuum_vac_cost_limit > 0 ?
- autovacuum_vac_cost_limit : VacuumCostLimit);
- double vac_cost_delay = (autovacuum_vac_cost_delay >= 0 ?
- autovacuum_vac_cost_delay : VacuumCostDelay);
- double cost_total;
- double cost_avail;
- dlist_iter iter;
-
- /* not set? nothing to do */
- if (vac_cost_limit <= 0 || vac_cost_delay <= 0)
- return;
- /* calculate the total base cost limit of participating active workers */
- cost_total = 0.0;
- dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
+ if (av_storage_param_cost_limit > 0)
+ vacuum_cost_limit = av_storage_param_cost_limit;
+ else
{
- WorkerInfo worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
+ int nworkers_for_balance;
+
+ if (autovacuum_vac_cost_limit > 0)
+ vacuum_cost_limit = autovacuum_vac_cost_limit;
+ else
+ vacuum_cost_limit = VacuumCostLimit;
+
+ /* Only balance limit if no cost-related storage parameters specified */
+ if (pg_atomic_unlocked_test_flag(&MyWorkerInfo->wi_dobalance))
+ return;
+
+ Assert(vacuum_cost_limit > 0);
- if (worker->wi_proc != NULL &&
- worker->wi_dobalance &&
- worker->wi_cost_limit_base > 0 && worker->wi_cost_delay > 0)
- cost_total +=
- (double) worker->wi_cost_limit_base / worker->wi_cost_delay;
+ nworkers_for_balance = pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
+
+ /* There is at least 1 autovac worker (this worker) */
+ if (nworkers_for_balance <= 0)
+ elog(ERROR, "nworkers_for_balance must be > 0");
+
+ vacuum_cost_limit = Max(vacuum_cost_limit / nworkers_for_balance, 1);
}
+}
- /* there are no cost limits -- nothing to do */
- if (cost_total <= 0)
- return;
+/*
+ * autovac_recalculate_workers_for_balance
+ * Recalculate the number of workers to consider, given cost-related
+ * storage parameters and the current number of active workers.
+ *
+ * Caller must hold the AutovacuumLock in at least shared mode to access
+ * worker->wi_proc.
+ */
+static void
+autovac_recalculate_workers_for_balance(void)
+{
+ dlist_iter iter;
+ int orig_nworkers_for_balance;
+ int nworkers_for_balance = 0;
+
+ Assert(LWLockHeldByMe(AutovacuumLock));
+
+ orig_nworkers_for_balance =
+ pg_atomic_read_u32(&AutoVacuumShmem->av_nworkersForBalance);
- /*
- * Adjust cost limit of each active worker to balance the total of cost
- * limit to autovacuum_vacuum_cost_limit.
- */
- cost_avail = (double) vac_cost_limit / vac_cost_delay;
dlist_foreach(iter, &AutoVacuumShmem->av_runningWorkers)
{
WorkerInfo worker = dlist_container(WorkerInfoData, wi_links, iter.cur);
- if (worker->wi_proc != NULL &&
- worker->wi_dobalance &&
- worker->wi_cost_limit_base > 0 && worker->wi_cost_delay > 0)
- {
- int limit = (int)
- (cost_avail * worker->wi_cost_limit_base / cost_total);
-
- /*
- * We put a lower bound of 1 on the cost_limit, to avoid division-
- * by-zero in the vacuum code. Also, in case of roundoff trouble
- * in these calculations, let's be sure we don't ever set
- * cost_limit to more than the base value.
- */
- worker->wi_cost_limit = Max(Min(limit,
- worker->wi_cost_limit_base),
- 1);
- }
+ if (worker->wi_proc == NULL ||
+ pg_atomic_unlocked_test_flag(&worker->wi_dobalance))
+ continue;
- if (worker->wi_proc != NULL)
- elog(DEBUG2, "autovac_balance_cost(pid=%d db=%u, rel=%u, dobalance=%s cost_limit=%d, cost_limit_base=%d, cost_delay=%g)",
- worker->wi_proc->pid, worker->wi_dboid, worker->wi_tableoid,
- worker->wi_dobalance ? "yes" : "no",
- worker->wi_cost_limit, worker->wi_cost_limit_base,
- worker->wi_cost_delay);
+ nworkers_for_balance++;
}
+
+ if (nworkers_for_balance != orig_nworkers_for_balance)
+ pg_atomic_write_u32(&AutoVacuumShmem->av_nworkersForBalance,
+ nworkers_for_balance);
}
/*
@@ -2421,23 +2471,34 @@ do_autovacuum(void)
continue;
}
- /* Must hold AutovacuumLock while mucking with cost balance info */
- LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
+ /*
+ * Save the cost-related storage parameter values in global variables
+ * for reference when updating vacuum_cost_delay and vacuum_cost_limit
+ * during vacuuming this table.
+ */
+ av_storage_param_cost_delay = tab->at_storage_param_vac_cost_delay;
+ av_storage_param_cost_limit = tab->at_storage_param_vac_cost_limit;
- /* advertise my cost delay parameters for the balancing algorithm */
- MyWorkerInfo->wi_dobalance = tab->at_dobalance;
- MyWorkerInfo->wi_cost_delay = tab->at_vacuum_cost_delay;
- MyWorkerInfo->wi_cost_limit = tab->at_vacuum_cost_limit;
- MyWorkerInfo->wi_cost_limit_base = tab->at_vacuum_cost_limit;
+ /*
+ * We only expect this worker to ever set the flag, so don't bother
+ * checking the return value. We shouldn't have to retry.
+ */
+ if (tab->at_dobalance)
+ pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
+ else
+ pg_atomic_clear_flag(&MyWorkerInfo->wi_dobalance);
- /* do a balance */
- autovac_balance_cost();
+ LWLockAcquire(AutovacuumLock, LW_SHARED);
+ autovac_recalculate_workers_for_balance();
+ LWLockRelease(AutovacuumLock);
- /* set the active cost parameters from the result of that */
+ /*
+ * We wait until this point to update cost delay and cost limit
+ * values, even though we reloaded the configuration file above, so
+ * that we can take into account the cost-related storage parameters.
+ */
VacuumUpdateCosts();
- /* done */
- LWLockRelease(AutovacuumLock);
/* clean up memory before each iteration */
MemoryContextResetAndDeleteChildren(PortalContext);
@@ -2521,16 +2582,17 @@ deleted:
pfree(tab);
/*
- * Remove my info from shared memory. We could, but intentionally
- * don't, clear wi_cost_limit and friends --- this is on the
- * assumption that we probably have more to do with similar cost
- * settings, so we don't want to give up our share of I/O for a very
- * short interval and thereby thrash the global balance.
+ * Remove my info from shared memory. We set wi_dobalance on the
+ * assumption that we are more likely than not to vacuum a table with
+ * no cost-related storage parameters next, so we want to claim our
+ * share of I/O as soon as possible to avoid thrashing the global
+ * balance.
*/
LWLockAcquire(AutovacuumScheduleLock, LW_EXCLUSIVE);
MyWorkerInfo->wi_tableoid = InvalidOid;
MyWorkerInfo->wi_sharedrel = false;
LWLockRelease(AutovacuumScheduleLock);
+ pg_atomic_test_set_flag(&MyWorkerInfo->wi_dobalance);
}
/*
@@ -2562,6 +2624,7 @@ deleted:
{
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
+ VacuumUpdateCosts();
}
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
@@ -2797,8 +2860,6 @@ table_recheck_autovac(Oid relid, HTAB *table_toast_map,
int freeze_table_age;
int multixact_freeze_min_age;
int multixact_freeze_table_age;
- int vac_cost_limit;
- double vac_cost_delay;
int log_min_duration;
/*
@@ -2808,20 +2869,6 @@ table_recheck_autovac(Oid relid, HTAB *table_toast_map,
* defaults, autovacuum's own first and plain vacuum second.
*/
- /* -1 in autovac setting means use plain vacuum_cost_delay */
- vac_cost_delay = (avopts && avopts->vacuum_cost_delay >= 0)
- ? avopts->vacuum_cost_delay
- : (autovacuum_vac_cost_delay >= 0)
- ? autovacuum_vac_cost_delay
- : VacuumCostDelay;
-
- /* 0 or -1 in autovac setting means use plain vacuum_cost_limit */
- vac_cost_limit = (avopts && avopts->vacuum_cost_limit > 0)
- ? avopts->vacuum_cost_limit
- : (autovacuum_vac_cost_limit > 0)
- ? autovacuum_vac_cost_limit
- : VacuumCostLimit;
-
/* -1 in autovac setting means use log_autovacuum_min_duration */
log_min_duration = (avopts && avopts->log_min_duration >= 0)
? avopts->log_min_duration
@@ -2877,8 +2924,10 @@ table_recheck_autovac(Oid relid, HTAB *table_toast_map,
tab->at_params.multixact_freeze_table_age = multixact_freeze_table_age;
tab->at_params.is_wraparound = wraparound;
tab->at_params.log_min_duration = log_min_duration;
- tab->at_vacuum_cost_limit = vac_cost_limit;
- tab->at_vacuum_cost_delay = vac_cost_delay;
+ tab->at_storage_param_vac_cost_limit = avopts ?
+ avopts->vacuum_cost_limit : 0;
+ tab->at_storage_param_vac_cost_delay = avopts ?
+ avopts->vacuum_cost_delay : -1;
tab->at_relname = NULL;
tab->at_nspname = NULL;
tab->at_datname = NULL;
@@ -3380,10 +3429,18 @@ AutoVacuumShmemInit(void)
worker = (WorkerInfo) ((char *) AutoVacuumShmem +
MAXALIGN(sizeof(AutoVacuumShmemStruct)));
+
/* initialize the WorkerInfo free list */
for (i = 0; i < autovacuum_max_workers; i++)
+ {
dlist_push_head(&AutoVacuumShmem->av_freeWorkers,
&worker[i].wi_links);
+
+ pg_atomic_init_flag(&worker[i].wi_dobalance);
+ }
+
+ pg_atomic_init_u32(&AutoVacuumShmem->av_nworkersForBalance, 0);
+
}
else
Assert(found);
diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h
index 50caf1315d..2a856b0e5e 100644
--- a/src/include/commands/vacuum.h
+++ b/src/include/commands/vacuum.h
@@ -350,6 +350,7 @@ extern IndexBulkDeleteResult *vac_cleanup_one_index(IndexVacuumInfo *ivinfo,
extern Size vac_max_items_to_alloc_size(int max_items);
/* In postmaster/autovacuum.c */
+extern void AutoVacuumUpdateCostLimit(void);
extern void VacuumUpdateCosts(void);
/* in commands/vacuumparallel.c */
--
2.37.2
From 92fc87969a496c1a1f5fd612d3c7c32251dec6e1 Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplage...@gmail.com>
Date: Thu, 6 Apr 2023 16:02:12 -0400
Subject: [PATCH v18 2/3] Separate vacuum cost variables from GUCs
Vacuum code run both by autovacuum workers and a backend doing
VACUUM/ANALYZE previously inspected VacuumCostLimit and VacuumCostDelay,
which are the global variables backing the GUCs vacuum_cost_limit and
vacuum_cost_delay.
Autovacuum workers needed to override these variables with their own
values, derived from autovacuum_vacuum_cost_limit and
autovacuum_vacuum_cost_delay and worker cost limit balancing logic. This
led to confusing code which, in some cases, both derived and set a new
value of VacuumCostLimit from VacuumCostLimit.
In preparation for refreshing these GUC values more often, introduce
new, independent global variables and add a function to update them
using the GUCs and existing logic.
Per suggestion by Kyotaro Horiguchi
Reviewed-by: Masahiko Sawada <sawada.m...@gmail.com>
Reviewed-by: Daniel Gustafsson <dan...@yesql.se>
Reviewed-by: Kyotaro Horiguchi <horikyota....@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAAKRu_ZngzqnEODc7LmS1NH04Kt6Y9huSjz5pp7%2BDXhrjDA0gw%40mail.gmail.com
---
src/backend/commands/vacuum.c | 29 +++++++++++++++--------
src/backend/commands/vacuumparallel.c | 3 ++-
src/backend/postmaster/autovacuum.c | 34 +++++++++++----------------
src/include/commands/vacuum.h | 5 ++++
src/include/postmaster/autovacuum.h | 3 ---
5 files changed, 40 insertions(+), 34 deletions(-)
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 7fc5c19e37..f2be74cdb5 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -72,6 +72,15 @@ int vacuum_multixact_freeze_table_age;
int vacuum_failsafe_age;
int vacuum_multixact_failsafe_age;
+/*
+ * Variables for cost-based vacuum delay. The defaults differ between
+ * autovacuum and vacuum. They should be set with the appropriate GUC value in
+ * vacuum code. They are initialized here to the defaults for client backends
+ * executing VACUUM or ANALYZE.
+ */
+double vacuum_cost_delay = 0;
+int vacuum_cost_limit = 200;
+
/*
* VacuumFailsafeActive is a defined as a global so that we can determine
* whether or not to re-enable cost-based vacuum delay when vacuuming a table.
@@ -514,8 +523,9 @@ vacuum(List *relations, VacuumParams *params, BufferAccessStrategy bstrategy,
{
ListCell *cur;
+ VacuumUpdateCosts();
in_vacuum = true;
- VacuumCostActive = (VacuumCostDelay > 0);
+ VacuumCostActive = (vacuum_cost_delay > 0);
VacuumCostBalance = 0;
VacuumPageHit = 0;
VacuumPageMiss = 0;
@@ -2244,14 +2254,14 @@ vacuum_delay_point(void)
*/
if (VacuumSharedCostBalance != NULL)
msec = compute_parallel_delay();
- else if (VacuumCostBalance >= VacuumCostLimit)
- msec = VacuumCostDelay * VacuumCostBalance / VacuumCostLimit;
+ else if (VacuumCostBalance >= vacuum_cost_limit)
+ msec = vacuum_cost_delay * VacuumCostBalance / vacuum_cost_limit;
/* Nap if appropriate */
if (msec > 0)
{
- if (msec > VacuumCostDelay * 4)
- msec = VacuumCostDelay * 4;
+ if (msec > vacuum_cost_delay * 4)
+ msec = vacuum_cost_delay * 4;
pgstat_report_wait_start(WAIT_EVENT_VACUUM_DELAY);
pg_usleep(msec * 1000);
@@ -2268,8 +2278,7 @@ vacuum_delay_point(void)
VacuumCostBalance = 0;
- /* update balance values for workers */
- AutoVacuumUpdateDelay();
+ VacuumUpdateCosts();
/* Might have gotten an interrupt while sleeping */
CHECK_FOR_INTERRUPTS();
@@ -2319,11 +2328,11 @@ compute_parallel_delay(void)
/* Compute the total local balance for the current worker */
VacuumCostBalanceLocal += VacuumCostBalance;
- if ((shared_balance >= VacuumCostLimit) &&
- (VacuumCostBalanceLocal > 0.5 * ((double) VacuumCostLimit / nworkers)))
+ if ((shared_balance >= vacuum_cost_limit) &&
+ (VacuumCostBalanceLocal > 0.5 * ((double) vacuum_cost_limit / nworkers)))
{
/* Compute sleep time based on the local cost balance */
- msec = VacuumCostDelay * VacuumCostBalanceLocal / VacuumCostLimit;
+ msec = vacuum_cost_delay * VacuumCostBalanceLocal / vacuum_cost_limit;
pg_atomic_sub_fetch_u32(VacuumSharedCostBalance, VacuumCostBalanceLocal);
VacuumCostBalanceLocal = 0;
}
diff --git a/src/backend/commands/vacuumparallel.c b/src/backend/commands/vacuumparallel.c
index 563117a8f6..cc0aff7904 100644
--- a/src/backend/commands/vacuumparallel.c
+++ b/src/backend/commands/vacuumparallel.c
@@ -995,7 +995,8 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
false);
/* Set cost-based vacuum delay */
- VacuumCostActive = (VacuumCostDelay > 0);
+ VacuumCostActive = (vacuum_cost_delay > 0);
+ VacuumUpdateCosts();
VacuumCostBalance = 0;
VacuumPageHit = 0;
VacuumPageMiss = 0;
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index c1e911b1b3..3644b86443 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -1773,16 +1773,24 @@ FreeWorkerInfo(int code, Datum arg)
}
/*
- * Update the cost-based delay parameters, so that multiple workers consume
- * each a fraction of the total available I/O.
+ * Update vacuum cost-based delay-related parameters for autovacuum workers and
+ * backends executing VACUUM or ANALYZE using the value of relevant gucs and
+ * global state. This must be called during setup for vacuum and after every
+ * config reload to ensure up-to-date values.
*/
void
-AutoVacuumUpdateDelay(void)
+VacuumUpdateCosts(void)
{
if (MyWorkerInfo)
{
- VacuumCostDelay = MyWorkerInfo->wi_cost_delay;
- VacuumCostLimit = MyWorkerInfo->wi_cost_limit;
+ vacuum_cost_delay = MyWorkerInfo->wi_cost_delay;
+ vacuum_cost_limit = MyWorkerInfo->wi_cost_limit;
+ }
+ else
+ {
+ /* Must be explicit VACUUM or ANALYZE */
+ vacuum_cost_delay = VacuumCostDelay;
+ vacuum_cost_limit = VacuumCostLimit;
}
}
@@ -2311,8 +2319,6 @@ do_autovacuum(void)
autovac_table *tab;
bool isshared;
bool skipit;
- double stdVacuumCostDelay;
- int stdVacuumCostLimit;
dlist_iter iter;
CHECK_FOR_INTERRUPTS();
@@ -2415,14 +2421,6 @@ do_autovacuum(void)
continue;
}
- /*
- * Remember the prevailing values of the vacuum cost GUCs. We have to
- * restore these at the bottom of the loop, else we'll compute wrong
- * values in the next iteration of autovac_balance_cost().
- */
- stdVacuumCostDelay = VacuumCostDelay;
- stdVacuumCostLimit = VacuumCostLimit;
-
/* Must hold AutovacuumLock while mucking with cost balance info */
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
@@ -2436,7 +2434,7 @@ do_autovacuum(void)
autovac_balance_cost();
/* set the active cost parameters from the result of that */
- AutoVacuumUpdateDelay();
+ VacuumUpdateCosts();
/* done */
LWLockRelease(AutovacuumLock);
@@ -2533,10 +2531,6 @@ deleted:
MyWorkerInfo->wi_tableoid = InvalidOid;
MyWorkerInfo->wi_sharedrel = false;
LWLockRelease(AutovacuumScheduleLock);
-
- /* restore vacuum cost GUCs for the next iteration */
- VacuumCostDelay = stdVacuumCostDelay;
- VacuumCostLimit = stdVacuumCostLimit;
}
/*
diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h
index 1223d15e0d..50caf1315d 100644
--- a/src/include/commands/vacuum.h
+++ b/src/include/commands/vacuum.h
@@ -307,6 +307,8 @@ extern PGDLLIMPORT pg_atomic_uint32 *VacuumActiveNWorkers;
extern PGDLLIMPORT int VacuumCostBalanceLocal;
extern PGDLLIMPORT bool VacuumFailsafeActive;
+extern PGDLLIMPORT double vacuum_cost_delay;
+extern PGDLLIMPORT int vacuum_cost_limit;
/* in commands/vacuum.c */
extern void ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel);
@@ -347,6 +349,9 @@ extern IndexBulkDeleteResult *vac_cleanup_one_index(IndexVacuumInfo *ivinfo,
IndexBulkDeleteResult *istat);
extern Size vac_max_items_to_alloc_size(int max_items);
+/* In postmaster/autovacuum.c */
+extern void VacuumUpdateCosts(void);
+
/* in commands/vacuumparallel.c */
extern ParallelVacuumState *parallel_vacuum_init(Relation rel, Relation *indrels,
int nindexes, int nrequested_workers,
diff --git a/src/include/postmaster/autovacuum.h b/src/include/postmaster/autovacuum.h
index c140371b51..65afd1ea1e 100644
--- a/src/include/postmaster/autovacuum.h
+++ b/src/include/postmaster/autovacuum.h
@@ -63,9 +63,6 @@ extern int StartAutoVacWorker(void);
/* called from postmaster when a worker could not be forked */
extern void AutoVacWorkerFailed(void);
-/* autovacuum cost-delay balancer */
-extern void AutoVacuumUpdateDelay(void);
-
#ifdef EXEC_BACKEND
extern void AutoVacLauncherMain(int argc, char *argv[]) pg_attribute_noreturn();
extern void AutoVacWorkerMain(int argc, char *argv[]) pg_attribute_noreturn();
--
2.37.2
From 0042067ce72a474fe4087245b978847c0b835b72 Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplage...@gmail.com>
Date: Fri, 31 Mar 2023 10:38:39 -0400
Subject: [PATCH v18 1/3] Make vacuum failsafe_active global
While vacuuming a table in failsafe mode, VacuumCostActive should not be
re-enabled. This currently isn't a problem because vacuum cost
parameters are only refreshed in between vacuuming tables and failsafe
status is reset for every table. In preparation for allowing vacuum cost
parameters to be updated more frequently, elevate
LVRelState->failsafe_active to a global, VacuumFailsafeActive, which
will be checked when determining whether or not to re-enable vacuum
cost-related delays.
Reviewed-by: Masahiko Sawada <sawada.m...@gmail.com>
Reviewed-by: Daniel Gustafsson <dan...@yesql.se>
Reviewed-by: Kyotaro Horiguchi <horikyota....@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAAKRu_ZngzqnEODc7LmS1NH04Kt6Y9huSjz5pp7%2BDXhrjDA0gw%40mail.gmail.com
---
src/backend/access/heap/vacuumlazy.c | 16 +++++++---------
src/backend/commands/vacuum.c | 15 +++++++++++++++
src/include/commands/vacuum.h | 1 +
3 files changed, 23 insertions(+), 9 deletions(-)
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 639179aa46..2ba85bd3d6 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -153,8 +153,6 @@ typedef struct LVRelState
bool aggressive;
/* Use visibility map to skip? (disabled by DISABLE_PAGE_SKIPPING) */
bool skipwithvm;
- /* Wraparound failsafe has been triggered? */
- bool failsafe_active;
/* Consider index vacuuming bypass optimization? */
bool consider_bypass_optimization;
@@ -391,7 +389,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
Assert(params->index_cleanup != VACOPTVALUE_UNSPECIFIED);
Assert(params->truncate != VACOPTVALUE_UNSPECIFIED &&
params->truncate != VACOPTVALUE_AUTO);
- vacrel->failsafe_active = false;
+ VacuumFailsafeActive = false;
vacrel->consider_bypass_optimization = true;
vacrel->do_index_vacuuming = true;
vacrel->do_index_cleanup = true;
@@ -709,7 +707,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
}
else
{
- if (!vacrel->failsafe_active)
+ if (!VacuumFailsafeActive)
appendStringInfoString(&buf, _("index scan bypassed: "));
else
appendStringInfoString(&buf, _("index scan bypassed by failsafe: "));
@@ -2293,7 +2291,7 @@ lazy_vacuum(LVRelState *vacrel)
* vacuuming or heap vacuuming. This VACUUM operation won't end up
* back here again.
*/
- Assert(vacrel->failsafe_active);
+ Assert(VacuumFailsafeActive);
}
/*
@@ -2374,7 +2372,7 @@ lazy_vacuum_all_indexes(LVRelState *vacrel)
*/
Assert(vacrel->num_index_scans > 0 ||
vacrel->dead_items->num_items == vacrel->lpdead_items);
- Assert(allindexes || vacrel->failsafe_active);
+ Assert(allindexes || VacuumFailsafeActive);
/*
* Increase and report the number of index scans.
@@ -2616,12 +2614,12 @@ static bool
lazy_check_wraparound_failsafe(LVRelState *vacrel)
{
/* Don't warn more than once per VACUUM */
- if (vacrel->failsafe_active)
+ if (VacuumFailsafeActive)
return true;
if (unlikely(vacuum_xid_failsafe_check(&vacrel->cutoffs)))
{
- vacrel->failsafe_active = true;
+ VacuumFailsafeActive = true;
/*
* Abandon use of a buffer access strategy to allow use of all of
@@ -2820,7 +2818,7 @@ should_attempt_truncation(LVRelState *vacrel)
{
BlockNumber possibly_freeable;
- if (!vacrel->do_rel_truncate || vacrel->failsafe_active ||
+ if (!vacrel->do_rel_truncate || VacuumFailsafeActive ||
old_snapshot_threshold >= 0)
return false;
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index ea1d8960f4..7fc5c19e37 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -72,6 +72,21 @@ int vacuum_multixact_freeze_table_age;
int vacuum_failsafe_age;
int vacuum_multixact_failsafe_age;
+/*
+ * VacuumFailsafeActive is a defined as a global so that we can determine
+ * whether or not to re-enable cost-based vacuum delay when vacuuming a table.
+ * If failsafe mode has been engaged, we will not re-enable cost-based delay
+ * for the table until after vacuuming has completed, regardless of other
+ * settings.
+ *
+ * Only VACUUM code should inspect this variable and only table access methods
+ * should set it to true. In Table AM-agnostic VACUUM code, this variable is
+ * inspected to determine whether or not to allow cost-based delays. Table AMs
+ * are free to set it if they desire this behavior, but it is false by default
+ * and reset to false in between vacuuming each relation.
+ */
+bool VacuumFailsafeActive = false;
+
/*
* Variables for cost-based parallel vacuum. See comments atop
* compute_parallel_delay to understand how it works.
diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h
index 19ca818dc2..1223d15e0d 100644
--- a/src/include/commands/vacuum.h
+++ b/src/include/commands/vacuum.h
@@ -306,6 +306,7 @@ extern PGDLLIMPORT pg_atomic_uint32 *VacuumSharedCostBalance;
extern PGDLLIMPORT pg_atomic_uint32 *VacuumActiveNWorkers;
extern PGDLLIMPORT int VacuumCostBalanceLocal;
+extern PGDLLIMPORT bool VacuumFailsafeActive;
/* in commands/vacuum.c */
extern void ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel);
--
2.37.2
