MDEV-34753 memory pressure - erroneous termination condition

Fix race condition in test case by waiting for the expected state to occur.

Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>

Author: knielsen

mysql-test/include/search_pattern_in_file.inc

@@ -18,6 +18,10 @@
 #    Optionally, SEARCH_ABORT can be set to "FOUND" or "NOT FOUND" and this
 #    will abort if the search result doesn't match the requested one.
 #
+#    Optionally, SEARCH_WAIT can be set to "FOUND" or "NOT FOUND", and this
+#    will wait for the condition to occur. The timeout can be set in
+#    SEARCH_TIMEOUT, default is 60 seconds.
+#
 #    Optionally, SEARCH_OUTPUT can be set to control the format of output.
 #    Supported formats:
 #     - (default)  : "FOUND n /pattern/ in FILE " or "NOT FOUND ..."
@@ -55,31 +59,50 @@ perl;
     my @search_files= glob($ENV{SEARCH_FILE});
     my $search_pattern= $ENV{SEARCH_PATTERN} or die "SEARCH_PATTERN not set";
     my $search_range=   $ENV{SEARCH_RANGE};
-    my $content;
-    foreach my $search_file (@search_files) {
-        open(FILE, '<', $search_file) || die("Can't open file $search_file: $!");
-        my $file_content;
-        if ($search_range > 0) {
-           read(FILE, $file_content, $search_range, 0);
-        } elsif ($search_range < 0) {
-           my $size= -s $search_file;
-           $search_range = -$size if $size > -$search_range;
-           seek(FILE, $search_range, 2);
-           read(FILE, $file_content, -$search_range, 0);
-        } else {
-          while(<FILE>) { # error log
-            if (/^CURRENT_TEST:/) {
-              $content='';
+    my $timeout=        $ENV{SEARCH_TIMEOUT} || 60;
+    my @matches;
+    my $res;
+
+    my $start_time= time();
+    for (;;) {
+        my $content;
+        foreach my $search_file (@search_files) {
+            open(FILE, '<', $search_file) || die("Can't open file $search_file: $!");
+            my $file_content;
+            if ($search_range > 0) {
+               read(FILE, $file_content, $search_range, 0);
+            } elsif ($search_range < 0) {
+               my $size= -s $search_file;
+               $search_range = -$size if $size > -$search_range;
+               seek(FILE, $search_range, 2);
+               read(FILE, $file_content, -$search_range, 0);
             } else {
-              $content.=$_;
+              while(<FILE>) { # error log
+                if (/^CURRENT_TEST:/) {
+                  $content='';
+                } else {
+                  $content.=$_;
+                }
+              }
+            }
+            close(FILE);
+            $content.= $file_content;
+        }
+        @matches= ($content =~ /$search_pattern/gs);
+        $res=@matches ? "FOUND " . scalar(@matches) : "NOT FOUND";
+
+        if (($ENV{SEARCH_WAIT} eq 'FOUND' && $res eq 'NOT FOUND') ||
+            ($ENV{SEARCH_WAIT} eq 'NOT FOUND' && $res =~ m{^FOUND })) {
+            if (time() - $start_time < $timeout) {
+                # Millisceond sleep emulated with select
+                select(undef, undef, undef, 0.1);
+                next;
             }
-          }
+            die "Timeout waiting for $ENV{SEARCH_WAIT} ".
+                "for /$search_pattern/ in $ENV{SEARCH_FILE}\n";
         }
-        close(FILE);
-        $content.= $file_content;
+        last;
     }
-    my @matches= ($content =~ /$search_pattern/gs);
-    my $res=@matches ? "FOUND " . scalar(@matches) : "NOT FOUND";
 
     $ENV{SEARCH_FILE} =~ s{^.*?([^/\\]+)$}{$1};
 

mysql-test/suite/innodb/t/mem_pressure.test

@@ -38,11 +38,16 @@ let SEARCH_FILE= $MYSQLTEST_VARDIR/log/mysqld.1.err;
 let SEARCH_PATTERN= [Mm]emory pressure.*;
 --source include/search_pattern_in_file.inc
 
-SELECT CAST(VARIABLE_VALUE AS INTEGER) < @dirty_prev AS LESS_DIRTY_IS_GOOD
-FROM INFORMATION_SCHEMA.GLOBAL_STATUS
-WHERE VARIABLE_NAME='Innodb_buffer_pool_pages_dirty';
-
+# The garbage collection happens asynchronously after trigger, in a background
+# thread. So wait for it to happen to avoid sporadic failure.
+let $wait_condition=
+  SELECT CAST(VARIABLE_VALUE AS INTEGER) < @dirty_prev AS LESS_DIRTY_IS_GOOD
+  FROM INFORMATION_SCHEMA.GLOBAL_STATUS
+  WHERE VARIABLE_NAME='Innodb_buffer_pool_pages_dirty';
+--source include/wait_condition.inc
+eval $wait_condition;
 let SEARCH_PATTERN= InnoDB: Memory pressure event freed.*;
+let SEARCH_WAIT= FOUND;
 --source include/search_pattern_in_file.inc
 
 set debug_dbug=@save_dbug;