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Fix autovacuum work item error handling

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In autovacuum's "work item" processing, a few strings were allocated in
the current transaction's memory context, which goes away during error
handling; if an error happened during execution of the work item, the
pfree() calls to clean up afterwards would try to release already-released
memory, possibly leading to a crash.  In branch master, this was already
fixed by commit 335f3d04e4c8, so backpatch that to REL_10_STABLE to fix
the problem there too.

As a secondary problem, verify that the autovacuum worker is connected
to the right database for each work item; otherwise some items would be
discarded by workers in other databases.

Reported-by: Justin Pryzby
Discussion: https://postgr.es/m/20171014035732.GB31726@telsasoft.com
This commit is contained in:
Alvaro Herrera 2017-10-30 15:52:13 +01:00
parent 0f1fbe7122
commit 52ca7572c3
1 changed files with 20 additions and 8 deletions
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28
src/backend/postmaster/autovacuum.c
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@ -2444,8 +2444,10 @@ do_autovacuum(void)
*/
PG_TRY();
{
/* Use PortalContext for any per-table allocations */
MemoryContextSwitchTo(PortalContext);
/* have at it */
MemoryContextSwitchTo(TopTransactionContext);
autovacuum_do_vac_analyze(tab, bstrategy);
/*
@ -2482,6 +2484,9 @@ do_autovacuum(void)
}
PG_END_TRY();
/* Make sure we're back in AutovacMemCxt */
MemoryContextSwitchTo(AutovacMemCxt);
did_vacuum = true;
/* the PGXACT flags are reset at the next end of transaction */
@ -2525,6 +2530,8 @@ deleted:
continue;
if (workitem->avw_active)
continue;
if (workitem->avw_database != MyDatabaseId)
continue;
/* claim this one, and release lock while performing it */
workitem->avw_active = true;
@ -2533,8 +2540,7 @@ deleted:
perform_work_item(workitem);
/*
* Check for config changes before acquiring lock for further
* jobs.
* Check for config changes before acquiring lock for further jobs.
*/
CHECK_FOR_INTERRUPTS();
if (got_SIGHUP)
@ -2601,10 +2607,9 @@ perform_work_item(AutoVacuumWorkItem *workitem)
/*
* Save the relation name for a possible error message, to avoid a catalog
* lookup in case of an error. If any of these return NULL, then the
* relation has been dropped since last we checked; skip it. Note: they
* must live in a long-lived memory context because we call vacuum and
* analyze in different transactions.
* relation has been dropped since last we checked; skip it.
*/
Assert(CurrentMemoryContext == AutovacMemCxt);
cur_relname = get_rel_name(workitem->avw_relation);
cur_nspname = get_namespace_name(get_rel_namespace(workitem->avw_relation));
@ -2614,6 +2619,9 @@ perform_work_item(AutoVacuumWorkItem *workitem)
autovac_report_workitem(workitem, cur_nspname, cur_datname);
/* clean up memory before each work item */
MemoryContextResetAndDeleteChildren(PortalContext);
/*
* We will abort the current work item if something errors out, and
* continue with the next one; in particular, this happens if we are
@ -2622,9 +2630,10 @@ perform_work_item(AutoVacuumWorkItem *workitem)
*/
PG_TRY();
{
/* have at it */
MemoryContextSwitchTo(TopTransactionContext);
/* Use PortalContext for any per-work-item allocations */
MemoryContextSwitchTo(PortalContext);
/* have at it */
switch (workitem->avw_type)
{
case AVW_BRINSummarizeRange:
@ -2668,6 +2677,9 @@ perform_work_item(AutoVacuumWorkItem *workitem)
}
PG_END_TRY();
/* Make sure we're back in AutovacMemCxt */
MemoryContextSwitchTo(AutovacMemCxt);
/* We intentionally do not set did_vacuum here */
/* be tidy */