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Limit memory usage of pg_walinspect functions.

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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 a use 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 10:29:53 -08:00
parent c6c3b3bc3d
commit 69e8c7cf1d
1 changed files with 53 additions and 5 deletions
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58
contrib/pg_walinspect/pg_walinspect.c
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@ -304,6 +304,8 @@ pg_get_wal_fpi_info(PG_FUNCTION_ARGS)
XLogRecPtr start_lsn;
XLogRecPtr end_lsn;
XLogReaderState *xlogreader;
MemoryContext old_cxt;
MemoryContext tmp_cxt;
start_lsn = PG_GETARG_LSN(0);
end_lsn = PG_GETARG_LSN(1);
@ -314,14 +316,26 @@ pg_get_wal_fpi_info(PG_FUNCTION_ARGS)
xlogreader = InitXLogReaderState(start_lsn);
tmp_cxt = AllocSetContextCreate(CurrentMemoryContext,
"pg_get_wal_fpi_info 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);
GetWALFPIInfo(fcinfo, xlogreader);
/* clean up and switch back */
MemoryContextSwitchTo(old_cxt);
MemoryContextReset(tmp_cxt);
CHECK_FOR_INTERRUPTS();
}
MemoryContextDelete(tmp_cxt);
pfree(xlogreader->private_data);
XLogReaderFree(xlogreader);
@ -440,23 +454,37 @@ GetWALRecordsInfo(FunctionCallInfo fcinfo, XLogRecPtr start_lsn,
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
Datum values[PG_GET_WAL_RECORDS_INFO_COLS] = {0};
bool nulls[PG_GET_WAL_RECORDS_INFO_COLS] = {0};
MemoryContext old_cxt;
MemoryContext tmp_cxt;
InitMaterializedSRF(fcinfo, 0);
xlogreader = InitXLogReaderState(start_lsn);
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);
@ -560,11 +588,13 @@ GetXLogSummaryStats(XLogStats *stats, ReturnSetInfo *rsinfo,
Datum *values, bool *nulls, uint32 ncols,
bool stats_per_record)
{
uint64 total_count = 0;
uint64 total_rec_len = 0;
uint64 total_fpi_len = 0;
uint64 total_len = 0;
int ri;
MemoryContext old_cxt;
MemoryContext tmp_cxt;
uint64 total_count = 0;
uint64 total_rec_len = 0;
uint64 total_fpi_len = 0;
uint64 total_len = 0;
int ri;
/*
* Each row shows its percentages of the total, so make a first pass to
@ -581,6 +611,10 @@ GetXLogSummaryStats(XLogStats *stats, ReturnSetInfo *rsinfo,
}
total_len = total_rec_len + total_fpi_len;
tmp_cxt = AllocSetContextCreate(CurrentMemoryContext,
"GetXLogSummaryStats temporary cxt",
ALLOCSET_DEFAULT_SIZES);
for (ri = 0; ri <= RM_MAX_ID; ri++)
{
uint64 count;
@ -614,6 +648,8 @@ GetXLogSummaryStats(XLogStats *stats, ReturnSetInfo *rsinfo,
if (count == 0)
continue;
old_cxt = MemoryContextSwitchTo(tmp_cxt);
/* the upper four bits in xl_info are the rmgr's */
id = desc.rm_identify(rj << 4);
if (id == NULL)
@ -626,6 +662,10 @@ GetXLogSummaryStats(XLogStats *stats, ReturnSetInfo *rsinfo,
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
values, nulls);
/* clean up and switch back */
MemoryContextSwitchTo(old_cxt);
MemoryContextReset(tmp_cxt);
}
}
else
@ -635,14 +675,22 @@ GetXLogSummaryStats(XLogStats *stats, ReturnSetInfo *rsinfo,
fpi_len = stats->rmgr_stats[ri].fpi_len;
tot_len = rec_len + fpi_len;
old_cxt = MemoryContextSwitchTo(tmp_cxt);
FillXLogStatsRow(desc.rm_name, count, total_count, rec_len,
total_rec_len, fpi_len, total_fpi_len, tot_len,
total_len, values, nulls, ncols);
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
values, nulls);
/* clean up and switch back */
MemoryContextSwitchTo(old_cxt);
MemoryContextReset(tmp_cxt);
}
}
MemoryContextDelete(tmp_cxt);
}
/*