From: Tatsuo Ishii <ishii@postgresql.org>
Date: Sun, 4 Dec 2005 01:22:42 +0000 (+0000)
Subject: Two fixes from Tom Lan. See the posting "[PATCHES] A couple of
X-Git-Tag: REL8_1_1~41
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=3824460544e223b3e0d529e3a6313a533a7c5726;p=postgresql

Two fixes from Tom Lan. See the posting "[PATCHES] A couple of
proposed pgbench changes" on 2005/11/29 for more details.

The change at line 490 updates doCustom's local variable "commands"
after selecting a new file (command sequence).  I think that the
existing coding will cause the thing to use the first command of the
old sequence in the remainder of the routine, which would be a bug.
I have not tried to set up a test case to prove it, though.

The other two changes cause doCustom to loop after processing a
meta-command.  This might be a bit controversial, but as the code
is currently written, each meta-command "costs" one cycle of the
outer select() loop.  Thus, for example, with the default TPC-B script,
once a backend returns "COMMIT" it will not receive a new command
until four cycles of issuing commands to other backends have elapsed.
(You can see this very easily by strace'ing pgbench under load.)
---

diff --git a/contrib/pgbench/pgbench.c b/contrib/pgbench/pgbench.c
index 8e99963033..ae8c4fe5e4 100644
--- a/contrib/pgbench/pgbench.c
+++ b/contrib/pgbench/pgbench.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/pgbench/pgbench.c,v 1.45.2.2 2005/11/23 13:23:34 ishii Exp $
+ * $PostgreSQL: pgsql/contrib/pgbench/pgbench.c,v 1.45.2.3 2005/12/04 01:22:42 ishii Exp $
  *
  * pgbench: a simple benchmark program for PostgreSQL
  * written by Tatsuo Ishii
@@ -411,6 +411,7 @@ doCustom(CState * state, int n, int debug)
 	CState	   *st = &state[n];
 	Command   **commands;
 
+top:
 	commands = sql_files[st->use_file];
 
 	if (st->listen)
@@ -489,6 +490,7 @@ doCustom(CState * state, int n, int debug)
 		{
 			st->state = 0;
 			st->use_file = getrand(0, num_files - 1);
+			commands = sql_files[st->use_file];
 		}
 	}
 
@@ -572,6 +574,8 @@ doCustom(CState * state, int n, int debug)
 			free(val);
 			st->listen = 1;
 		}
+
+		goto top;
 	}
 }