From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 19 Jan 2006 21:49:30 +0000 (+0000)
Subject: Add some test scaffolding to allow cache-flush stress testing (and I do
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=c09e73429f04821e35c2efe62298bab2df3adc67;p=users%2Fbernd%2Fpostgres.git

Add some test scaffolding to allow cache-flush stress testing (and I do
mean stress ... system is orders of magnitude slower with this enabled).
---

diff --git a/src/backend/utils/cache/inval.c b/src/backend/utils/cache/inval.c
index e09bb385dd..a8046468a3 100644
--- a/src/backend/utils/cache/inval.c
+++ b/src/backend/utils/cache/inval.c
@@ -625,6 +625,36 @@ AcceptInvalidationMessages(void)
 {
 	ReceiveSharedInvalidMessages(LocalExecuteInvalidationMessage,
 								 InvalidateSystemCaches);
+
+	/*
+	 * Test code to force cache flushes anytime a flush could happen.
+	 *
+	 * If used with CLOBBER_FREED_MEMORY, CLOBBER_CACHE_ALWAYS provides a
+	 * fairly thorough test that the system contains no cache-flush hazards.
+	 * However, it also makes the system unbelievably slow --- the regression
+	 * tests take about 100 times longer than normal.
+	 *
+	 * If you're a glutton for punishment, try CLOBBER_CACHE_RECURSIVELY.
+	 * This slows things by at least a factor of 10000, so I wouldn't suggest
+	 * trying to run the entire regression tests that way.  It's useful to
+	 * try a few simple tests, to make sure that cache reload isn't subject
+	 * to internal cache-flush hazards, but after you've done a few thousand
+	 * recursive reloads it's unlikely you'll learn more.
+	 */
+#if defined(CLOBBER_CACHE_ALWAYS)
+	{
+		static bool in_recursion = false;
+
+		if (!in_recursion)
+		{
+			in_recursion = true;
+			InvalidateSystemCaches();
+			in_recursion = false;
+		}
+	}
+#elif defined(CLOBBER_CACHE_RECURSIVELY)
+	InvalidateSystemCaches();
+#endif
 }
 
 /*