database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-27 23:21:58 +03:00
Code Activity

Unpin buffer before inplace update waits for an XID to end.

Browse Source 
Commit a07e03fd8f changed inplace updates
to wait for heap_update() commands like GRANT TABLE and GRANT DATABASE.
By keeping the pin during that wait, a sequence of autovacuum workers
and an uncommitted GRANT starved one foreground LockBufferForCleanup()
for six minutes, on buildfarm member sarus.  Prevent, at the cost of a
bit of complexity.  Back-patch to v12, like the earlier commit.  That
commit and heap_inplace_lock() have not yet appeared in any release.

Discussion: https://postgr.es/m/20241026184936.ae.nmisch@google.com
This commit is contained in:
Noah Misch
2024-10-29 09:39:55 -07:00
parent 74f70cb863
commit 0fe002d0c9
3 changed files with 14 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
src/backend/access/heap/heapam.c
View File

@ -6134,8 +6134,8 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
* transaction. If compatible, return true with the buffer exclusive-locked,
* and the caller must release that by calling
* heap_inplace_update_and_unlock(), calling heap_inplace_unlock(), or raising
* an error. Otherwise, return false after blocking transactions, if any,
* have ended.
* an error. Otherwise, call release_callback(arg), wait for blocking
* transactions to end, and return false.
*
* Since this is intended for system catalogs and SERIALIZABLE doesn't cover
* DDL, this doesn't guarantee any particular predicate locking.
@ -6169,7 +6169,8 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
*/
bool
heap_inplace_lock(Relation relation,
HeapTuple oldtup_ptr, Buffer buffer)
HeapTuple oldtup_ptr, Buffer buffer,
void (*release_callback) (void *), void *arg)
{
HeapTupleData oldtup = *oldtup_ptr; /* minimize diff vs. heap_update() */
TM_Result result;
@ -6234,6 +6235,7 @@ heap_inplace_lock(Relation relation,
lockmode, NULL))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
release_callback(arg);
ret = false;
MultiXactIdWait((MultiXactId) xwait, mxact_status, infomask,
relation, &oldtup.t_self, XLTW_Update,
@ -6249,6 +6251,7 @@ heap_inplace_lock(Relation relation,
else
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
release_callback(arg);
ret = false;
XactLockTableWait(xwait, relation, &oldtup.t_self,
XLTW_Update);
@ -6260,6 +6263,7 @@ heap_inplace_lock(Relation relation,
if (!ret)
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
release_callback(arg);
}
}