From 499d1cf55d3d07b29bc80b10f8abca4fb0458154 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 7 Feb 2025 13:41:43 -0500 Subject: [PATCH] Fix pgbench performance issue induced by commit af35fe501. Commit af35fe501 caused "pgbench -i" to emit a '\r' character for each data row loaded (when stderr is a terminal). That's effectively invisible on-screen, but it causes the connected terminal program to consume a lot of cycles. It's even worse if you're connected over ssh, as the data then has to pass through the ssh tunnel. Simplest fix is to move the added logic inside the if-tests that check whether to print a progress line. We could do it another way that avoids duplicating these few lines, but on the whole this seems the most transparent way to write it. Like the previous commit, back-patch to all supported versions. Reported-by: Andres Freund Author: Tom Lane Reviewed-by: Nathan Bossart Discussion: https://postgr.es/m/4k4drkh7bcmdezq6zbkhp25mnrzpswqi2o75d5uv2eeg3aq6q7@b7kqdmzzwzgb Backpatch-through: 13 --- src/bin/pgbench/pgbench.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c index 8b2e61d27e0..f3af142f690 100644 --- a/src/bin/pgbench/pgbench.c +++ b/src/bin/pgbench/pgbench.c @@ -5009,6 +5009,16 @@ initGenerateDataClientSide(PGconn *con) j, (int64) naccounts * scale, (int) (((int64) j * 100) / (naccounts * (int64) scale)), elapsed_sec, remaining_sec); + + /* + * If the previous progress message is longer than the current + * one, add spaces to the current line to fully overwrite any + * remaining characters from the previous message. + */ + if (prev_chars > chars) + fprintf(stderr, "%*c", prev_chars - chars, ' '); + fputc(eol, stderr); + prev_chars = chars; } /* let's not call the timing for each row, but only each 100 rows */ else if (use_quiet && (j % 100 == 0)) @@ -5023,20 +5033,20 @@ initGenerateDataClientSide(PGconn *con) j, (int64) naccounts * scale, (int) (((int64) j * 100) / (naccounts * (int64) scale)), elapsed_sec, remaining_sec); + /* + * If the previous progress message is longer than the current + * one, add spaces to the current line to fully overwrite any + * remaining characters from the previous message. + */ + if (prev_chars > chars) + fprintf(stderr, "%*c", prev_chars - chars, ' '); + fputc(eol, stderr); + prev_chars = chars; + /* skip to the next interval */ log_interval = (int) ceil(elapsed_sec / LOG_STEP_SECONDS); } } - - /* - * If the previous progress message is longer than the current one, - * add spaces to the current line to fully overwrite any remaining - * characters from the previous message. - */ - if (prev_chars > chars) - fprintf(stderr, "%*c", prev_chars - chars, ' '); - fputc(eol, stderr); - prev_chars = chars; } if (eol != '\n')