Fix memory leak in pgstat_progress_parallel_incr_param()

When called from a parallel worker, this function calls initStringInfo()
and pq_beginmessage(), causing a StringInfo allocation to happen twice.
pq_endmessage() frees only the second allocation, with each call leaking
~1 kB into the per-worker memory context.  This could cause a few
hundred megabytes worth of memory to pile up until the worker exits (the
message allocations happen in the parallel worker context), with the
situation being worse the longer a parallel worker runs.

Oversight in f1889729dd3.

Author: Baji Shaik <baji.pgdev@gmail.com>
Reviewed-by: Sami Imseih <samimseih@gmail.com>
Reviewed-by: Tristan Partin <tristan@partin.io>
Discussion: https://postgr.es/m/CA+fm-RMopta1Dmq8udiU5sp+zwTvhUf4+xfbr3rZDfczH+p-xw@mail.gmail.com
Backpatch-through: 17

diff --git a/src/backend/utils/activity/backend_progress.c b/src/backend/utils/activity/backend_progress.c
index b0359771de50aa707e598573024c7b17d6efded0..6d2049105abaaf717cdf04e2b9269179ff4b0320 100644 (file)
--- a/src/backend/utils/activity/backend_progress.c
+++ b/src/backend/utils/activity/backend_progress.c
@@ -100,8 +100,6 @@ pgstat_progress_parallel_incr_param(int index, int64 incr)
        {
                static StringInfoData progress_message;
 
-               initStringInfo(&progress_message);
-
                pq_beginmessage(&progress_message, PqMsg_Progress);
                pq_sendint32(&progress_message, index);
                pq_sendint64(&progress_message, incr);