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Limit memory usage of pg_walinspect functions. 

GetWALRecordsInfo() and pg_get_wal_fpi_info() can leak memory across
WAL record iterations. Fix this by using a temporary memory context
that's reset for each WAL record iteraion.

Also use a temporary context for loops in GetXLogSummaryStats(). The
number of iterations is a small constant, so the previous behavior was
not a leak, but fix for clarity (but no need to backport).

Backport GetWALRecordsInfo() change to version
15. pg_get_wal_fpi_info() didn't exist in version 15.

Reported-by: Peter Geoghegan
Author: Bharath Rupireddy
Discussion: https://www.postgresql.org/message-id/CAH2-WznLEJjn7ghmKOABOEZYuJvkTk%3DGKU3m0%2B-XBAH%2BerPiJQ%40mail.gmail.com
Backpatch-through: 15
This commit is contained in:
Jeff Davis 2023-02-20 11:29:31 -08:00
parent 305d89ad93
commit da32a99df1
1 changed files with 14 additions and 0 deletions
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14
contrib/pg_walinspect/pg_walinspect.c
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@ -332,6 +332,8 @@ GetWALRecordsInfo(FunctionCallInfo fcinfo, XLogRecPtr start_lsn,
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
Datum values[PG_GET_WAL_RECORDS_INFO_COLS];
bool nulls[PG_GET_WAL_RECORDS_INFO_COLS];
MemoryContext old_cxt;
MemoryContext tmp_cxt;
InitMaterializedSRF(fcinfo, 0);
@ -340,18 +342,30 @@ GetWALRecordsInfo(FunctionCallInfo fcinfo, XLogRecPtr start_lsn,
MemSet(values, 0, sizeof(values));
MemSet(nulls, 0, sizeof(nulls));
tmp_cxt = AllocSetContextCreate(CurrentMemoryContext,
"GetWALRecordsInfo temporary cxt",
ALLOCSET_DEFAULT_SIZES);
while (ReadNextXLogRecord(xlogreader) &&
xlogreader->EndRecPtr <= end_lsn)
{
/* Use the tmp context so we can clean up after each tuple is done */
old_cxt = MemoryContextSwitchTo(tmp_cxt);
GetWALRecordInfo(xlogreader, values, nulls,
PG_GET_WAL_RECORDS_INFO_COLS);
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
values, nulls);
/* clean up and switch back */
MemoryContextSwitchTo(old_cxt);
MemoryContextReset(tmp_cxt);
CHECK_FOR_INTERRUPTS();
}
MemoryContextDelete(tmp_cxt);
pfree(xlogreader->private_data);
XLogReaderFree(xlogreader);